U.S. patent application number 10/744671 was filed with the patent office on 2004-12-23 for compositions produced by solvent exchange methods and uses thereof.
Invention is credited to Haghighat, R. Ross, Mojazza, Hamid R., Ryu, Jae, Schuler, Peter, Vinciguerra, Michael A..
Application Number | 20040258952 10/744671 |
Document ID | / |
Family ID | 27402200 |
Filed Date | 2004-12-23 |
United States Patent
Application |
20040258952 |
Kind Code |
A1 |
Haghighat, R. Ross ; et
al. |
December 23, 2004 |
Compositions produced by solvent exchange methods and uses
thereof
Abstract
Disclosed are compositions formed by a method for exchanging
solvent in a mixture that includes water and an optionally
substituted thiophene. Also disclosed are methods for making and
using such compositions.
Inventors: |
Haghighat, R. Ross;
(Westford, MA) ; Ryu, Jae; (Lowell, MA) ;
Mojazza, Hamid R.; (Chelmsford, MA) ; Vinciguerra,
Michael A.; (Hampton, NH) ; Schuler, Peter;
(Westwood, MA) |
Correspondence
Address: |
Pepper Hamilton LLP
Firm 21269
One Mellon Center, 50th Floor
500 Grant Street
Pittsburgh
PA
15219
US
|
Family ID: |
27402200 |
Appl. No.: |
10/744671 |
Filed: |
December 22, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10744671 |
Dec 22, 2003 |
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09999171 |
Nov 30, 2001 |
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6692662 |
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60298174 |
Jun 13, 2001 |
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60269606 |
Feb 16, 2001 |
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Current U.S.
Class: |
428/690 |
Current CPC
Class: |
C08G 61/126 20130101;
Y02P 70/50 20151101; C09D 165/00 20130101; H01L 51/5088 20130101;
Y02E 60/13 20130101; C08G 73/1057 20130101; H01G 11/48 20130101;
H01G 11/56 20130101; H01L 51/0037 20130101; C08G 73/1039 20130101;
H01G 9/028 20130101; Y02E 10/549 20130101 |
Class at
Publication: |
428/690 |
International
Class: |
B32B 009/00 |
Claims
What is claimed is:
1. A composition comprising: a combination of an aqueous dispersion
of an optionally substituted poly-3,4 alkylene dioxythiophene
cation and an associated polyanion; and 1% (w/v) to 100% (w/v) of
one or more organic solvents, wherein the one or more organic
solvents have a boiling point between from about 80.degree. C. to
about 290.degree. C., wherein at least 30% (w/v) of the water from
the aqueous dispersion is removed from said combination.
2. The composition of claim 1, wherein at least 90% of the water
from the aqueous dispersion is removed.
3. The composition of claim 1, wherein the polyanion is polystyrene
sulfonic acid (PSS).
4. The composition of claim 1, wherein the aqueous dispersion of
said optionally substituted poly-3,4-alkylene dioxythiophene
includes an aqueous dispersion of 0.5-5% by weight of
poly-3,4-ethylene dioxythiophene and the anion is polystyrene
sulfonic acid.
5. The composition of claim 1 further comprising at least one
additive.
6. The composition of claim 5, wherein the additive is a
binder.
7. The composition of claim 5, wherein the additive is ferric
toluene sulfonic acid.
8. The composition of claim 7, wherein the ferric toluene sulfonic
acid is present in trace amounts.
9. The composition of claim 1, wherein a coating of the composition
has at least an order of magnitude higher conductivity than a
coating of the corresponding unexchanged optionally substituted
poly-3,4-alkylene dioxythiophene aqueous dispersion.
10. The composition of claim 1 wherein the aqueous dispersion of
said optionally substituted poly-3,4-alkylene dioxythiophene
includes an aqueous dispersion of 0.5-5% by weight of
poly-3,4-ethylene dioxythiophene and the anion is polystyrene
sulfonic acid.
11. The composition of claim 1 the aqueous dispersion of the
optionally substituted poly-3,4-alkylene dioxythiophene cation and
an associated polyanion is from about 0.38% to about 1.55% by
weight of said composition.
12. The composition of claim 1 wherein the one or more organic
solvents include lower alkyl acetamides, lower alcohols, diol
alcohols, triol alcohols, pyrrolidones, lower alkyl pyrrolidones,
higher alkyl pyrrolidones, lower alkyl sulfoxides, or mixtures
thereof.
13. The composition of claim 1, wherein the one or more organic
solvent is glycol or glycerin.
14. The composition of claim 1, wherein the one or more organic
solvents is dimethylsulfoxide.
15. The composition of claim 1, wherein the one or more organic
solvents is a mixture of ethylene glycol and
N-methylpyrrolidone.
16. The composition of claim 1, wherein the one or more organic
solvents is a mixture of ethylene glycol, dimethylacetamide, and
N-methylphyrrolidone.
17. The composition of claim 1, wherein the polyanion is an anion
of a polymeric carboxylic acid, a polymaleic acid, a polymeric
sulphonic acid, or mixtures thereof.
18. The composition of claim 1, wherein the one or more organic
solvents have a boiling point between from about 100.degree. C. to
about 250.degree. C.
19. A coating comprising a composition comprising: a combination of
an aqueous dispersion of an optionally substituted poly-3,4
alkylene dioxythiophene cation and an associated polyanion; and 1%
(w/v) to 100% (w/v) of one or more organic solvents that include
ethylene glycol, dimethylacetamide, N-methylpyrrolidone, or
mixtures thereof, wherein at least 30% (w/v)of the water from the
aqueous dispersion is removed from said combination.
20. The coating of claim 19, wherein at least 90% of the water from
the aqueous dispersion is removed.
21. The coating of claim 19, wherein the polyanion is polystyrene
sulfonic acid (PSS).
22. The coating of claim 19, wherein the aqueous dispersion of said
optionally substituted poly-3,4-alkylene dioxythiophene includes an
aqueous dispersion of 0.5-5% by weight of poly-3,4-ethylene
dioxythiophene and the anion is polystyrene sulfonic acid.
23. The coating of claim 19, further comprising at least one
additive.
24. The coating of claim 23, wherein the additive is a binder.
25. The coating of claim 23, wherein the additive is ferric toluene
sulfonic acid.
26. The coating of claim 25, wherein the ferric toluene sulfonic
acid is present in trace amounts.
27. The coating of claim 19, wherein the aqueous dispersion of said
optionally substituted poly-3,4-alkylene dioxythiophene includes an
aqueous dispersion of 0.5-5% by weight of poly-3,4-ethylene
dioxythiophene and the anion is polystyrene sulfonic acid.
28. The coating of claim 19, the aqueous dispersion of the
optionally substituted poly-3,4-alkylene dioxythiophene cation and
an associated polyanion is from about 0.38% to about 1.55% by
weight of said composition.
29. The coating of claim 19, wherein the one or more organic
solvents has a boiling point of about 100.degree. C. to 250.degree.
C.
30. The coating of claim 19, wherein the one or more organic
solvents is a mixture of ethylene glycol and
N-methylpyrrolidone.
31. The coating of claim 19, wherein the polyanion is an anion of a
polymeric carboxylic acid, a polymaleic acid, a polymeric sulphonic
acid, or mixtures thereof.
32. The coating of claim 19, wherein the coating is configured as a
layer.
33. The coating of claim 32, wherein the layer has a surface
resistance of between from about 10 to about 10.sup.12
.OMEGA./sq.
34. The coating of claim 32 having between from about 1 mg/m.sup.2
to about 500 mg/m.sup.2 of the composition in the layer.
35. The coating of claim 32 in which the layer has an optical
density of between from about 0.0001 to about 0.05 at between from
about 300 nm to about 700 nm.
36. The coating of claim 32, wherein the layer has a light
transmission of between from about 10% to about 99% as measured by
a BYK Gardner Hazegard plus machine.
37. The coating of claim 32, wherein the layer has a light
transmission of between from about 80% to about 95% as measured by
a BYK Gardner Hazegard plus machine.
38. A coating of claim 19 further comprising least one polymer,
co-polymer, graft polymer, or blend thereof.
39. The coating of claim 38, comprising a polymer, wherein the
weight ratio of the composition to the polymer is about 10:90 to
about 0.1:99.9.
40. The coating of claim 38, comprising a polymer, wherein the
weight ratio of the composition to the polymer is about 6:94 to
about 0.5:99.5.
41. The coating of claim 38, comprising a polymer, wherein the
polymer is a polyimide.
42. The coating of claim 19, wherein the aqueous dispersion is
0.5-5% by weight of poly-3,4-ethylene dioxythiophene.
43. The coating of claim 19, wherein the coating exhibits a charge
carrier mobility of greater than 0.1 Cm.sup.2/V-S.
44. The coating of claim 19, wherein the coating is prepared by
employing non-vacuum, coating processes, wherein the coating
exhibits a charge carrier mobility of greater than 1
Cm.sup.2/V-S.
45. The coating of claim 19, wherein the coating exhibits a charger
carrier mobility of greater than 10 Cm.sup.2/V-S, wherein the
charge carrier mobility is measured by the combination of van der
Pauw and Hall effect methods.
46. A coating comprising a composition comprising: a combination of
an aqueous dispersion of an optionally substituted poly-3,4
alkylene dioxythiophene cation and an associated polyanion; and 1%
(w/v) to 100% (w/v) of one or more organic solvents, wherein the
one or more organic solvents have a boiling point between from
about 80.degree. C. to about 290.degree. C., wherein at least 30%
(w/v)of the water from the aqueous dispersion is removed from said
combination.
47. The coating of claim 46, wherein at least 90% of the water from
the aqueous dispersion is removed.
48. The coating of claim 46, wherein the polyanion is polystyrene
sulfonic acid (PSS).
49. The coating of claim 46, wherein the aqueous dispersion of said
optionally substituted poly-3,4-alkylene dioxythiophene includes an
aqueous dispersion of 0.5-5% by weight of poly-3,4-ethylene
dioxythiophene and the anion is polystyrene sulfonic acid.
50. The coating of claim 46, further comprising at least one
additive.
51. The coating of claim 50, wherein the additive is a binder.
52. The coating of claim 51, wherein the additive is ferric toluene
sulfonic acid.
53. The coating of claim 52, wherein the ferric toluene sulfonic
acid is present in trace amounts.
54. The coating of claim 46 wherein the aqueous dispersion of said
optionally substituted poly-3,4-alkylene dioxythiophene includes an
aqueous dispersion of 0.5-5% by weight of poly-3,4-ethylene
dioxythiophene and the anion is polystyrene sulfonic acid.
55. The coating of claim 46, the aqueous dispersion of the
optionally substituted poly-3,4-alkylene dioxythiophene cation and
an associated polyanion is from about 0.38% to about 1.55% by
weight of said composition.
56. The coating of claim 46, wherein the one or more organic
solvents include lower alkyl acetamides, lower alcohols, including
diol and triol alcohols, pyrrolidones, lower alkyl pyrrolidones,
higher alkyl pyrrolidones, lower alkyl sulfoxides, or mixtures
thereof.
57. The coating of claim 46, wherein the one or more organic
solvent is glycol or glycerin.
58. The coating of claim 46, wherein the one or more organic
solvents is dimethylsulfoxide.
59. The coating of claim 46, wherein the one or more organic
solvents is a mixture of ethylene glycol and
N-methylpyrrolidone.
60. The coating of claim 46, wherein the one or more organic
solvents is a mixture of ethylene glycol, dimethylacetamide, and
N-methylphyrrolidone.
61. The coating of claim 46, wherein the one or more organic
solvents have a boiling point between from about 100.degree. C. to
about 250.degree. C.
62. The coating of claim 46, wherein the polyanion is an anion of a
polymeric carboxylic acid, a polymaleic acid, a polymeric sulphonic
acid, or mixtures thereof.
63. The coating of claim 46, wherein the coating is configured as a
layer.
64. The coating of claim 63, wherein the layer has a surface
resistance of between from about 10 to about 10.sup.12
.OMEGA./sq.
65. The coating of claim 63, having between from about 1 mg/m.sup.2
to about 500 mg/m.sup.2 of the composition in the layer.
66. The coating of claim 63, in which the layer has an optical
density of between from about 0.0001 to about 0.05 at between from
about 300 nm to about 700 nm.
67. The coating of claim 63, wherein the layer has a light
transmission of between from about 10% to about 99% as measured by
a BYK Gardner Hazegard plus machine.
68. The coating of claim 63, wherein the layer has a light
transmission of between from about 80% to about 95% as measured by
a BYK Gardner Hazegard plus machine.
69. A coating of claim 46 further comprising least one polymer,
co-polymer, graft polymer, or blend thereof.
70. The coating of claim 69 further comprising a polymer, wherein
the weight ratio of the composition to the polymer is about 10:90
to about 0.1:99.9.
71. The coating of claim 69, further comprising a polymer, wherein
the weight ratio of the composition to the polymer is about 6:94 to
about 0.5:99.5.
72. The coating of claim 69 further comprising a polymer wherein
the polymer is a polyimide.
73. The coating of claim 46 wherein the aqueous dispersion is
0.5-5% by weight of poly-3,4-ethylene dioxythiophene.
74. The coating of claim 46,wherein the coating exhibits a charge
carrier mobility of greater than 0.1 Cm.sup.2/V-S.
75. The coating of claim 46, wherein the coating is prepared by
employing non-vacuum, coating processes, wherein the coating
exhibits a charge carrier mobility of greater than 1
Cm.sup.2/V-S.
76. The coating of claim 46, wherein the coating exhibits a charger
carrier mobility of greater than 10 Cm.sup.2/V-S, wherein the
charge carrier mobility is measured by the combination of van der
Pauw and Hall effect methods.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a Continuation of U.S.
application Ser. No. 09/999,171 as filed on Nov. 30, 2001. U.S.
application Ser. No. 09/999,171 is a continuation-in-part of U.S.
Provisional Application No. 60/298,174 as filed on Jun. 13, 2001,
which application claims benefit to U.S. Provisional Application
No. 60/269,606 as filed on Feb. 16, 2001. The disclosures of the
U.S. application Ser. Nos. 09/999,171, 60/298,174 and 60/269,606
applications are each incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention generally relates to compositions
produced from solvent exchange processes. In general, the processes
replace water in a thiophene mixture with at least one other
solvent. A preferred thiophene mixture is a water saturated
Baytron.TM. formulation. Also provided are useful articles
including organic solvent based polymeric coatings as well as
methods for making and using same.
BACKGROUND OF THE INVENTION
[0003] There is increasing recognition that performance of a wide
spectrum of electronic and optical articles can be enhanced by
including a conductive molecule. Examples of such articles include
anti-static coatings, films, as well as a variety of electronic
implementations. See generally Handbook on Conducting Polymers
(Skotheim, T. J. ed.) (Dekker, N.Y., 1986).
[0004] Many types of conductive organic molecules have been
reported. For example, U.S. Pat. Nos. 6,172,591; 4,237,441; and
5,378,407 disclose organic polymers with a carbon black or metallic
conductive filler.
[0005] Organic polymers that are intrinsically conductive have
attracted substantial interest. Generally, such polymers include
sp.sup.2 hybridized carbon atoms that have (or can be adapted to
have) delocalized electrons for storing and communicating
electronic charge. Some polymers are thought to have conductivities
neighboring those traditional silicon-based and metallic
conductors. These and other performance characteristics make such
conductive polymers desirable for a wide range of applications. See
Burroughes, J. H. et al. (1986) Nature 335:137;Sirringhaus, H. et
al. (2000) Science, 290, 2123; Sirringhaus, H. et al. (1999) Nature
401: 2; and references cited therein, for example.
[0006] Other conductive polymers have been reported. These polymers
include a many optionally substituted polypyrrole, polyaniline,
polyacetylene, and polythiophene compounds. See EP-A 302 304; EP-A
440 957; DE OS 4 211 459; U.S. Pat. Nos. 6,083,635 and 6,084,040;
and Burroughes, J. H., supra.
[0007] There is recognition that many conductive polymers can be
used to coat a wide range of synthetic or natural articles such as
those made from glass, plastic, wood and fibers to provide an
electrostatic or anti-static coating. Typical coatings can be
applied as sprays, powders and the like using recognized coating or
printing processes.
[0008] However there is increasing understanding that many prior
conductive polymers are not useful for all intended applications.
For example, many of such polymers are not sufficiently conductive
or transparent for many applications. In particular, many suffer
from unacceptable conductivity, poor stability, and difficult
processing requirements. Other shortcomings have been reported. See
e.g, the U.S. Pat. Nos. 6,084,040 and 6,083,635.
[0009] There have been attempts to improve some of the prior
conductive polymers. For example, a particular 3,4-polyethylene
dioxythiophene (commercially available as Baytron.TM. P) has been
reported to offer good conductivity, transparency, stability,
hydrolysis resistance and processing characteristics. See Bayer A G
product literature (Edition October 1997; Order No. Al 5593)
Inorganics Business Group D-51368, Leverkusen, Germany.
[0010] More specific Baytron.TM. formulations have been reported
for use in specific applications. Illustrative formulations (P
type) include CPUD2, CPP103T, CPP105T, CPP116.6, CPP134.18, CP135,
CPP 4531 I, CPP 4531 E3 and CPG 130.6. Baytron.TM. M is reported to
be a monomer of poly(3,4-ethylenedioxythiophene) and it has been
reported to be useful in the manufacture of organic conductive
polymers. Further information relating to using Baytron.TM.
formulations can be obtained from the Bayer Corporation, 100 Bayer
Rd. Pittsburgh, Pa. 15205-9741. See also the Bayer Corporation
website at bayerus.com the disclosure of which is incorporated by
reference.
[0011] Unfortunately, use of many prior mono- and polythiophene
formulations has been problematic. For example, many important
Baytron.TM. formulations are provided with significant amounts of
water solvent. In particular, many Baytron.TM. P formulations are
available as water-saturated colloidal dispersions of the
conductive polymer. Typically, a suitable counter ion such as
polystyrene sulfonic acid (PSS) is added to the dispersion. There
is increasing recognition that many, if not all, Baytron.TM.
formulations would be more useful if means existed for exchanging
the water solvent with one or more other solvents of choice.
[0012] There have been limited attempts to develop such solvent
exchange methods. Nearly all of the attempts have relied on
traditional liquid fractionation and distillation schemes. Such
approaches have not been able to exchange the solvent for the water
in a way that is effective and reproducible.
[0013] Flexible electronic device "writing" or "printing" has
attracted much recent attention. An example of such a technique
involves dispersing an aqueous and conductive thiophene preparation
with an ink-jet printer. Typically,
poly(3,4-ethylenedioxythiophene) doped with polystyrene sulfonic
acid (PEDOT/PSS) is employed. See generally Dagni, R. in Chemistry
and Engineering, Jan. 1, 2001, pp. 26-27 as well as references
cited therein. However, these writing or printing procedures have
suffered for want of an effective and reproducible means of
replacing the water with more useful exchange solvents.
[0014] There is recognition that many electro-optic devices, such
as light emitting diodes (LED's) and photovoltaic cells, require
electrically conductive and optically transparent films/coatings as
electrode materials. Presently, transparent electrodes in
electro-optic devices are made of indium doped tin oxide (ITO)
coated glass substrates. However, most prior ITO layers have
suffered from shortcomings. For example, most prior manufacturing
processes involving ITO are cumbersome and costly to perform. An
illustration is the need to conduct vacuum deposition in a
controlled gas atmosphere. Furthermore, most prior ITO films are
brittle, difficult to prepare and manipulate, particularly when
used in film formats on large area substrates or flexible
substrates. See generally Y. Cao, et al. in Conjugated Polymeric
Materials: Opportunities in Electronics, Optoelectronics and
Molecular Electronics, NATO Advanced Study Institute, Series E:
Applied Sciences, J. L. Bredas and R. R. Chance, Eds., Vol. 82,
Kluwer Academic, Holland (1990). See also U.S. Pat. No. 5,618,469
and EPO Patent 686,662.
[0015] There is belief that certain conducting polymers and
coatings may be qualified for some organic light emitting diode
(OLED) applications. Briefly, OLEDs are display compositions based
on sandwiching deposited organic molecules or polymers between two
electrodes. Light emission or luminescence occurs when charged
carriers associate with the electrodes recombine and emit light.
See U.S. Pat. No. 5,904,961, for instance.
[0016] More specifically, a typical OLED includes a metal cathode,
electrode transport layer (ETL), organic emitters, the HIL, an ITO
anode and glass substrate. Light output passes through the glass
substrate.
[0017] Electrically conductive and optically transparent coatings
have been made with polyaniline (PANI) (U.S. Pat. No. 5,618,469)
and PEDOT/PSS polymer dispersion (Eur Patent 686662). However, many
of the prior coatings have recognized drawbacks particularly in
relation to OLED applications.
[0018] As an example, many have limitations in manufacturing
practical electro-optic devices. In particular, it is well known
that many PANI systems are not stable. Performance degrades over
time. Although there is some understanding that performance of
PEDOT:PSS-based devices are stable, many prior PEDOT/PSS polymers
are aqueous based. Fabricating PEDOT:PSS coatings onto ITO coated
substrates requires cumbersome manufacturing processes. Further,
the hydrophilic nature of the PEDOT:PSS system attracts moisture,
even through the protective moisture barrier. This characteristic
has several disadvantages including premature failure during
use.
[0019] It would be desirable to have coating and related
compositions that are easy to make and use. It would be especially
desirable to have solvent-exchanged PEDOT:PSS compositions as well
as methods for making and using same that exhibit low resistivity
and are suitable for OLED use.
SUMMARY OF THE INVENTION
[0020] The present invention relates to solvent exchange methods
for replacing water in a thiophene mixture. Preferred methods of
the invention replace some or all of the water with at least one
other solvent. Preferably, the thiophene mixture is a Baytron.TM.
formulation. Also provided are compositions produced by the methods
as well as useful articles that include or consist of such
compositions. The invention has a wide spectrum of important
applications including providing converted (solvent exchanged)
Baytron.TM. formulations for use in consumer goods and electronic
writing techniques.
[0021] As discussed, it has been difficult to replace the water
associated with many thiophene mixtures, particularly but not
exclusively, mono- and polythiophene mixtures known as Baytron.TM.
formulations. Such formulations are often provided as collodial or
water saturated materials. The present invention addresses this
need eg., by providing methods for replacing (exchanging) the water
with at least one other more desirable solvent. Significantly, the
present methods can be controlled by an invention user so that all
or part of the water in mixture is exchanged as needed. Also
significantly, the invention can be practiced using standard
laboratory equipment, thereby making the invention cost effective
in most embodiments. Preferred use of the invention expands the
usefulness of thiophene mixtures, particularly the Baytron.TM.
formulations, into applications that heretofore have been difficult
or impossible to practice.
[0022] The present invention also relates to compositions,
preferably polymer coatings, that are easy to make and use.
Typically, such compositions are relatively stable and involve use
of non- or low toxicity solvents. Preferred compositions according
to the invention are PEDOT:PSS compositions, more preferably
solvent-exchanged PEDOT:PSS coating compositions suitable for use
in a range of electro-optical implemenations including OLEDs.
[0023] Such compositions provide advantages including good
conductivity, high optical tranparency and environmental stability.
Significantly, preferred compositions of the invention can be used
to replace indium doped tin oxide (ITO) coated glass substrates
that are part of many standard OLEDs.
[0024] Also encompassed by the invention are methods for making and
using the present compositions. In one embodiment, the methods
involve subjecting PEDOT:PSS compositions to conditions that
decrease resistivity when compared to (control) compositions not
receiving such treatment. Preferred conditions generally involve at
least one drying treatment. Also disclosed are methods for making
such compositions in which at least one of the method steps
involves drying treatment. By the phrase "drying treatment" is
meant exposure to at least one condition that causes, either
directly or indirectly, loss of solvent from the composition,
preferably exchanged solvent.
[0025] The drying treatments provided by the invention provide
substantial advantages. In particular, practice of such treatment
steps in the methods of the invention provide a straightforward and
cost effective way of improving composition performance by
assisting solvent loss. Preferred practice involves subjecting
conductive coatings of the invention to ambient air and/or heat
treatment to help remove solvent, and has been discovered, to help
improve performance characteristics such as resistivity.
Significantly, such drying treatments are compatible with most
manufacturing processes and can be scaled-up as needed. More
specific information about the drying treatments is provided in the
discussion and examples following.
[0026] The invention also features electro-optical implementations
that include at least one of the compositions disclosed herein
including preferred PEDOT:PSS compositions. An illustration of such
an implementation is an OLED or related device. Such OLEDs reduce
or avoid use of hard-to-manipulate ITO components while providing
coatings with improved performance features, especially
resistivity. As provided below, it is an object of the invention to
replace prior ITO components with at least one of the compositions
of this invention provided as an OLED hole injection layer
(HIL).
[0027] Accordingly, and in one aspect, the invention provides
methods for exchanging (in whole or in part) the water present in a
thiophene mixture with at least one other solvent. A preferred
mixture includes at least one thiophene, preferably an optionally
substituted mono- or polythiophene, more preferably a water
saturated Baytron.TM. formulation. In one embodiment, the method
includes at least one and preferably all of the following
steps:
[0028] a) heating at least one solvent in a vessel under conditions
suitable for vaporizing water,
[0029] b) contacting the heated solvent with the thiophene mixture
(comprising the water and at least one optionally substituted mono-
or polythiophene), which contact is sufficient to remove at least
part of the water from the mixture as vapor; and
[0030] c) exchanging the water removed from the mixture with the
solvent.
[0031] Preferred practice of the invention involves heating the
solvent before contact with the thiophene mixture, although in some
invention embodiments substantially contemporaneous solvent heating
may be desirable. Preferred heating conditions favor production of
water vapor from the mixture. Without wishing to be bound to
theory, it is believed that heating the solvent before the contact
helps to reduce prolonged contact between the thiophene mixture and
the exchange solvent. Such limited contact has many benefits
including enhancing water loss from the mixture and increasing
exchange with the heated solvent. In contrast, prior practice has
been limited to more traditional distillation schemes featuring
gradual liquid heating and close solution contact. These schemes
are not always designed to minimize contact between the exchanging
solvent and the thiophene mixture. Such limited contact is also
believed to reduce or avoid binding potential (covalent and
non-covalent) between the water and exchange solvent. Such binding
is believed to have impeded many past attempts to reduce the amount
of or eliminate water from some thiophene mixtures. As will become
more apparent from the following discussion, these and other
features of the invention provide for more efficient solvent
exchange than has heretofore been possible, particularly with many
Baytron.TM. formulations.
[0032] Additionally preferred practice of the invention involves
maximizing the contact area of the heated solvent with respect to
the contact area of the thiophene mixture. Without wishing to be
bound to any theory, it is believed that by increasing the heated
solvent contact area relative to that of the thiophene mixture, it
is possible to boost heat transfer from the exchange solvent to the
mixture. In this invention example, the relatively large heated
solvent contact area helps to transfer heat quickly and efficiently
from the exchange solvent to the mixture. This invention feature
also helps to achieve an invention objective ie, the reduction or
elimination of unwanted binding between the water and exchange
solvent.
[0033] The invention provides many other important advantages. For
example, in another aspect, the invention provides highly useful
compositions that include or consist of at least one of the
converted (solvent exchanged) thiophene mixtures. A preferred
converted thiophene mixture is derived from an optionally
substituted mono- or polythiophene, particularly a Baytron.TM.
formulation in which the water solvent has been totally or
partially replaced with at least one other solvent. In this
invention embodiment, it has been found that such converted
thiophene mixtures feature better electrical conductivity than
corresponding unconverted (control) mixtures. Significantly, such
better conductivity is achieved with films and coatings having less
thickness than conventional films and coatings made from many
Baytron.TM. formulations. Without wishing to be bound to theory,
preferred practice of the invention is believed to provide for more
conductive polymer chain orientations. This and other features of
the invention will help expand the use of the Baytron.TM.
formulations into a variety of applications in which good
conductivity and minimal film or coating thickness is desired.
[0034] Turning to the invention methods, it will be understood that
it is possible to increase the contact area of the heated solvent
by one or a combination of strategies.
[0035] For example, in one embodiment, the foregoing solvent
exchange method further includes adding about 1 unit volume of the
thiophene mixture to more than about one unit volume of the heated
solvent e.g., at least about 2 unit volumes of the heated solvent
per unit volume of the mixture. The larger heated solvent volume
provides the relatively large heated solvent contact area to move
heat effectively from the exchange solvent to thiophene
mixture.
[0036] The heated solvent, thiophene mixture (or both), can be
provided in forms so that the heated solvent has a relatively large
contact area when compared to the mixture. As an example, the
contacting step of the methods can be adapted to include adding the
thiophene mixture to the vessel as a flow stream, mist, aerosol; or
a combination thereof having the larger contact area.
[0037] Typically, but not exclusively, the heated exchange solvent
is provided as a pool in the vessel which pool has the relatively
larger contact area relative to the added mixture. Addition of that
mixture to the vessel can be continuous or discontinuous as needed
e.g., as a semi-continuous flow stream or as drops of the mixture
added to the pool of heated solvent. In another example, the
contacting step of the method includes dispersing the mixture along
the surface of the heated solvent. Such dispersal can be continuous
or semi-continuous to further assist and maximize the contact area
of the heated exchange solvent relative to the thiophene mixture.
This example of the invention may be especially useful in instances
in which the exchange solvent, the mixture (or both) are available
in limited quantities. For some applications, it may be desirable
to add the mixture below the surface of the heated solvent.
[0038] The methods of the invention are generally flexible and can
be used to replace all or part of the water in a subject thiophene
mixture with at least one other desired solvent. This feature of
the invention further enhances the utility of many optionally
substituted mono- and polythiophenes and especially many of the
Baytron.TM. formulations. By way of illustration and not
limitation, the invention can be used to replace a pre-determined
amount of water in a Baytron.TM. M or P formulation with at least
one other solvent including a combination of different solvents. It
is thus possible to make many new thiophene mixtures and
particularly a wide variety of converted (solvent exchanged)
Baytron.TM. formulations. Such converted formulations having a
pre-determined amount of water exchanged for solvent or combination
of solvents can be used in a range of new applications.
[0039] As will be appreciated, the invention is compatible with a
wide spectrum of solvents. Typically, the exchange solvent will
include one solvent. However, for some applications it will be
useful to employ a combination of solvents as the exchanging medium
e.g, two to six solvents, preferably about two solvents. In another
embodiment, the invention methods can be adapted so that all or
part of the water in a thiophene mixture is exchanged for a first
solvent (or solvent combination). If the resulting converted
thiophene mixture includes unexchanged water, that water can be
further exchanged (fully or partially) with a second solvent (or
solvent combination), thereby making a further converted mixture.
Further solvent exchange can be performed as needed. Choice of a
particular solvent exchange procedure according to the invention
will by guided by recognized parameters including the use for which
a particular converted thiophene mixture is intended.
[0040] More specific solvents of the invention include those that
are stable to heat conditions favoring water vaporization. A more
preferred solvent or solvent combination for use in the method has
a boiling point of at least about 100.degree. C. at standard
pressure (1 atmosphere (atm)). However in embodiments in which the
water solvent can be vaporized below or above 100.degree. C. other
solvents may be more desirable e.g, those having boiling points
below or above 100.degree. C. at 1 atm. Exemplary embodiments
include practice of the method in which the vessel has an internal
pressure less or greater than about 1 atm. More specific exchange
solvent examples include polar and non-polar solvents as well as
solvents that are miscible or insoluble in water.
[0041] As mentioned, the invention provides compositions made
entirely or in part with at least one of the converted (solvent
exchanged) thiophene mixtures according to the invention. In one
embodiment, the composition is an azeotrope. That is, the
composition cannot be separated by fractional distillation into two
or more pure substances. Such azeotropes include maximum-boiling
azeotropes in which the boiling point of the heated solvent is
raised by contact with the water solvent. Also included are
minimum-boiling azeotropes in which the boiling point of the heated
solvent is depressed by contact with the water solvent.
[0042] Preferred compositions of the invention feature an
electrical conductivity that is at least about an order of
magnitude larger than the corresponding unconverted (no solvent
exchange) thiophene mixture when measured according to standard
procedures. Particular converted polydioxythiophenes of the
invention such as TOR-CP exhibit a conductivity increase that is
about one to two orders of magnitude greater than Baytron.TM.
P.
[0043] In another embodiment, the invention features more
particular methods that include forming a composition from the
mixture, preferably a coating composition, and subjecting that
composition to at least one drying treatment step as defined
herein. Preferably, the drying treatment is performed after step c)
of the method (ie. solvent exchange step). Such treatment may be
performed once or more than once as needed. More preferred drying
treatments involve significant exposure to ambient room temperature
or higher temperatures sufficient to remove solvent from the
composition. In embodiments in which more than one drying treatment
is desired eg., two, three or four of such treatments, the drying
treatments may be the same or different as needed to achieve a
particular result. In such embodiments, the drying treatments can
be performed in a tandem or discontinuous format. Generally, but
not exclusively, drying treatments of less than about one to two
days are suitable for most invention applications. Less than about
several hours, preferably less than a few hours will be preferred
for most invention applications. Compositions produced by such
methods are also featured herein.
[0044] In yet another aspect, the invention provides conductive
materials, particularly coating materials and films that include or
consist of the compositions provided by this invention. Preferred
films suitably include at least one polymer, co-polymer or mixture
thereof such as those disclosed below Such conductive materials are
well-adapted for use in anti-static or electrostatic
applications.
[0045] Also featured are conductive coatings that include or
consist of the compositions provided herein, preferably configured
as a layer having at least one of the following performance
characteristics: 1) good resistivity; 2) good surface resistance;
and 3) good optical transmission. Preferably, such compositions
exhibit at least good resistivity. Examples of preferred conductive
coatings are provided in the discussion that follows.
[0046] Also provided by the invention are articles of manufacture
that include or consist of at least one of the compositions and
coating materials of this invention.
[0047] In one embodiment, the articles are electro-optical
implementations and preferably organic light emitting devices
(OLED) such as those provided below.
[0048] In another aspect, the invention provides useful methods for
making an electronic implementation, typically by "writing" or
"printing", which methods include at least one and preferably all
of the following steps:
[0049] a) contacting at least one of the compositions disclosed
herein with a first polymer layer,
[0050] b) dissolving at least a portion of the first polymer layer
with the composition under conditions forming a hole, typically a
via-hole or interconnect, in the first polymer layer; and
[0051] c) evaporating the solvent in the composition to make the
electronic implementation.
[0052] The foregoing method for making the electronic
implementation has important advantages including providing better
control of solvent surface tension as well as enhanced writing or
printing alignment of the hole. Also provided are electronic
implementations and manufactured articles produced by the
method.
BRIEF DESCRIPTION OF THE DRAWINGS
[0053] FIG. 1 is a graph showing optical transmission versus
surface resistance of a converted (solvent exchanged) TOR-CP
(Triton AO Resistant Conductive Polymer made from converted
Baytron.TM. P) and Baytron P (neat). The TOR-CP was filtered or
non-filtered.
[0054] FIG. 2 is a graph showing volume resistance comparisons of
TOR-CP exchanged with N-methylpyrrolidone (NMP) in Matrimid.TM.
(Ciba) as polyimide; TOR-CP exchanged with di-methylacetimide
(DMAC) in TOR-NC (Triton AO Resistant polyimide); and TOR-CP
exchanged with NMP in TOR-NC.
[0055] FIG. 3 is a graph showing bulk film light transmission
versus volume resistance for the polymers described in FIG. 2,
above.
[0056] FIG. 4 is a table showing data from eight (8) samples of
Baytron.TM. P exchanged with NMP. The data provide conductivity,
viscosity, solids content, particle size distribution,
transmission, pH, density, and water content parameters.
[0057] FIG. 5 is a table showing data from eight (8) samples of
Baytron.TM. P exchanged with NMP. The data provide conductivity,
viscosity, solids content, particle size distribution,
transmission, pH, density, and water content parameters.
[0058] FIG. 6 is a table showing data from ten (10) samples of
Baytron.TM. P exchanged with NMP. Also shown are data from six (6)
samples of neat (non-solvent exchanged) Baytron.TM. P.
[0059] FIGS. 7A, 7B, and 7C are tables showing data from selected
samples of Baytron.TM. P exchanged with NMP or DMAc. Drawdown
surface resistances are also illustrated.
[0060] FIG. 8 is a formulation performance table showing thickness
and resistance properties of several TOR-CP batches.
[0061] FIGS. 9A-D are graphs showing resistivities of spin-coated
films of TOR-CP and Baytron-P on glass substrates as a function of
coating thickness.
[0062] FIG. 10 is a graph showing optical transparencies of
spin-coated films of TOR-CP and Baytron-P on glass substrates as a
function of wavelength.
[0063] FIG. 11 is a graph showing performance of a OLED of the
invention made with TOR-CP as a hole injection layer (HIL).
[0064] FIG. 12 is a table showing resistivity and surface
resistance data for selected TOR-CP and Baytron-P samples. The data
generally show that TOR-CP features better surface resistance and
resistivity characteristics than Baytron-P.
[0065] FIG. 13 is a graph showing surface resistance of CP coatings
and Baytron P on a PET substrate
[0066] FIG. 14 is graph showing light transmittance of CP coatings
and Baytron P on a PET substrate.
[0067] FIG. 15 is a table showing data in support of FIGS. 13 and
14.
[0068] FIG. 16 is a graph showing Ln-Ln conductivity data of Tor-CP
and Baytron P at various temperatures.
[0069] FIG. 17 is also a graph showing Ln-Ln conductivity data of
Tor-CP and Baytron P at various temperatures.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0070] As discussed, the invention provides highly useful methods
for replacing some or all of the water associated with many
thiophenes, preferably optionally substituted mono- and
polythiophene mixtures. More preferred mixtures include Baytron.TM.
formulations provided as M or P type. The invention has a variety
of important applications including providing electrically
conductive compositions useful in the manufacture of anti-static
and electrostatic coatings, capacitor electrodes (tantalum and
aluminum, for example), and through-hole plating of printed circuit
boards (PCBs). Further uses and advantages of the invention are
discussed below.
[0071] By the term "converted" "solvent exchange", "solvent
exchanged" or like words or phrases is meant replacement of some or
all of the water associated with the thiophene mixture for a
desired exchange solvent (or combination of solvents). Preferably,
the replacement of the water is at least about 30% (w/v) complete,
more preferably at least about 50% (w/v), even more preferably at
least about 90% (w/v) complete, most preferably at least about 99%
(w/v) complete with respect to the total volume of water originally
present in the mixture. As mentioned, it is an object of the
invention to reduce the amount of water present in the thiophene
mixture sufficient to replace at least some of that water and
sometimes essentially all of the water with a desired volume of the
exchange solvent or solvent combination. For many invention
applications, substantially complete substitution of the desired
solvent or solvent combination for the water in the mixture will be
generally preferred.
[0072] The invention is fully compatible with a wide range of
thiophene mixtures. A thiophene mixture refers to a material that
includes at least one optionally substituted mono- or
polythiophenes thiophene as disclosed herein which mixture
preferably includes water and optionally other components such as,
but not limited to, counterions, stabilizers, ect. Preferred are
cationically charged monodioxythiophenes and polydioxythiophenes
represented by the following formulae I and II: 1
[0073] wherein R1 and R2 each independently represent hydrogen or
an optionally substituted C1-C6 alkyl group, or together form an
optionally substituted C1-C6 radical, preferably a methylene
radical which is optionally substituted by lower alkyl groups, an
ethylene- 1,2 radical optionally substituted by C1-C12 lower alkyl
or phenyl groups, or an optionally substituted cyclohexylene-1,2
radical, n is 1; and the polythiophene is represented by the
following formula (II): 2
[0074] wherein R3 and R4 each independently represent hydrogen or
an optionally substituted C1-C6 alkyl group, or together form an
optionally substituted C1-C6 radical, preferably a methylene
radical which is optionally substituted by lower alkyl groups, an
ethylene-1,2 radical optionally substituted by C1-C12 lower alkyl
or phenyl groups, or an optionally substituted cyclohexylene-1,2
radical. Preferably, n1 in Formula II is greater than 1, preferably
about 2 to about 10,000, with between from about 5 to about 5000
being preferred for many applications.
[0075] By the term "optionally substituted" is meant substitution
with hydrogen, substituted or unsubstituted (C1-C18)-alkyl,
preferably (C1-C10)-, in particular (C1-C6)-alkyl,
(C2-C12)-alkenyl, preferably (C2 -C8)-alkenyl, (C3-C7)-cycloalkyl,
preferably cyclopentyl or cyclohexyl, (C7-C15)-aralkyl, preferably
phenyl-(C1-C4)-alkyl, (C6 -C 10)-aryl, preferably phenyl or
naphthyl, (C1-C18)-alkyloxy, preferably (C1-C10)-alkyloxy, for
example methoxy, ethoxy, n- or iso-propoxy, or (C2-C18)-alkyloxy
ester. Exemplary substitution groups include halogen, particularly
chlorine, fluorine and bromine; lower alkyl, alkenyl, alkynyl, or
alkoxy having 1 to 6 carbons, hydroxy, keto, allyl, and sulphonate,
for example.
[0076] More specific examples of the mono- and polydioxythiophenes
have been reported in U.S. Pat. Nos. 5,766,515, 6,083,835,
5,300,575, 6,157,479, EP-A 440 957, EP-A 339,340; the disclosures
of which are incorporated herein by reference. Particular
thiophenes of interest may, but do not necessarily include, one or
more organic compounds containing dihydroxy or polyhydroxy, and/or
carboxyl groups or amide groups e.g., lactam groups are
N-methylpyrrolidone, pyrrolidone, caprolactam, N-methylcaprolactam,
N-octylpyrrolidone. In embodiments in which such organic compounds
are desired, the mono- and polythiophenes will further include
sugar and sugar derivatives such as sucrose, glucose, fructose,
lactose; sugar alcohols such as sorbitol, mannitol; furan
derivatives such as 2-furancarboxylic acid, 3-furancarboxylic acid;
alcohols such as ethylene glycol, glycerol, di- or triethylene
glycol. See the U.S. Pat. No. 6,083,635, for example.
[0077] In many invention embodiments, the cationically charged
monodioxythiophenes and polydioxythiophenes of Formulae I and II
above, are each associated with one or more suitable polyanions.
Preferred polyanions are the anions of polymeric carboxylic acids
such as polyacrylic acids, polymethacrylic acids or polymaleic
acids or of polymeric sulphonic acids such as polystyrenesulphonic
acids and polyvinylsulphonic acids. These polycarboxylic and
polysulphonic acids can also be copolymers of vinylcarboxylic and
vinylsulphonic acids with other polymerizable monomers such as
acrylic esters and styrene. The anion of polystyrenesulphonic acid
is particularly preferred as counterion in most invention
embodiments.
[0078] The molecular weight of the polyacids providing the
polyanions is preferably from 1000 to 2,000,000, particularly
preferably from 2000 to 500,000. The polyacids or their alkali
metal salts are commercially available, e.g. polystyrenesulphonic
acids and polyacrylic acids, or else can be prepared by known
methods. Other suitable polyanions include mixtures of alkali metal
salts of polyacids and corresponding amounts of monoacids. See the
U.S. Pat. No. 6,157,479 and references cited therein.
[0079] Additionally preferred thiophenes according to the above
Formulae I and II include those in which R1, R2, R3 and R4 each
independently represent C1-C4 alkyl or together form a C1-C4
radical. More preferably, the monothiophene is an optionally
substituted mono-3,4-alkylene dioxythiophene such as
mono-3,4-ethylene dioxythiophene. Also preferred polythiophenes
include poly-3,4-alkylene dioxythiophene, preferably
poly-3,4-ethylene dioxythiophene. See also U.S. Pat. Nos. 5,294,372
and 5,066,731 for disclosure relating to other preferred thiophenes
including mono- and polydioxythiophenes.
[0080] More specifically preferred mono- and polydioxythiophenes
according to the invention are Baytron.TM. formulations (Bayer
Corporation, 100 Bayer Rd. Pittsburgh, Pa. 15205-9741). Such
polymer formulations are reported to be highly useful in the
manufacture of organic conductive polymers. Specific examples of
such formulations include, but are not limited to, those designated
as M or P formulations. Preferred P type formulations include
CPUD2, CPP103T, CPP105T, CPP116.6, CPP134.18, CP135, CPP 4531 I,
CPP 4531 E3 and CPG 130.6. A preferred Baytron.TM. M formulation is
a monomer of poly(3,4-ethylenedioxythiophene).
[0081] Although it will often be helpful to convert the Baytron.TM.
M to its corresponding polymeric form before practicing the
invention, use of Baytron.TM. M in the methods of this invention is
contemplated particularly in cases in which solvent exchanged
Baytron.TM. M formulations are desired. Procedures for converting
Baytron.TM. M to its polymeric form have been disclosed by the
Bayer Corporation.
[0082] See also the following patent references for additional
examples of suitable substituted or unsubstituted
thiophene-containing polymers: U.S. Pat. Nos. 4,731,408; 4,959,430;
4,987,042; 5,035,926; 5,300,575; 5,312,681; 5,354,613; 5,370,981;
5,372,924; 5,391,472; 5,403,467; 5,443,944; 5,463,056; 5,575,898;
and 5,747,412; the disclosures of which are each incorporated
herein by reference.
[0083] As discussed, the invention is fully compatible with use of
a wide array of solvents and solvent combinations. Generally,
choice of an exchange solvent or solvent combination will be guided
by recognized parameters including intended use for the converted
(solvent exchanged) mono- or polythiophene. A more specific example
of such a solvent is one that is stable (ie. does not degrade) to
at least about 100.degree. C. at standard temperature and pressure
(STP). A preferred solvent boiling point is between from about
100.degree. C. to about 250.degree. C. at STP. Additionally
preferred solvents can be fully or partially water soluble or water
insoluble as needed. By the term "solvent combination" or like
phrase is meant at least two mutually miscible solvents, preferably
two, three or four of such solvents.
[0084] More examples of suitable solvents include lower alkyl
acetamides, lower alcohols including diols and triols,
pyrrolidones, lower alkyl pyrrolidones, higher alkyl pyrrolidones,
lower alkyl sulfoxides; as well as mixtures thereof. A preferred
lower alcohol is glycol or glycerin. Suitable lower alkyl
sulfoxides include dimethylsulfoxide (DMSO). Specifically preferred
solvents for many invention embodiments are di-methylacetimide
(DMAC) and N-methylpyrrolidone (NMP). By the term "lower alkyl" is
meant between from about 1 to 20 carbon atoms (branched or straight
chain), preferably about 1 to about 10 of such carbon atoms, more
preferably about 1 to about 4 of such carbon atoms.
[0085] More particular solvents and co-solvents according to the
invention will vary e.g., according to intended use. Example of
such co-solvents and solvents include, but are not limited to,
acetonitrile, benzonitrile, lower alkyl cyanoacetates, preferably
methylcyanoacate; halogenated methanes, preferably dichloromethane;
diethyl ether, lower alkoxy ethanes, preferably dimethoxyethane;
N,N-dimethylformamide, nitrobenzene, nitromethane, propionitrile,
and propylene carbonate. By the term "lower alkoxy" is meant
methoxy, ethoxy, propoxy, isopropoxy, butyoxy; preferably methoxy.
A preferred halogenated methane is partially or fully chlorinated
or brominated e.g., dichloromethane and dibromomethane.
[0086] One or more of the foregoing preferred solvents can be
combined to provide a solvent combination. An illustrative solvent
combination would be a mixture of NMP and DMAc, eg., a 50:50 (v/v)
mixture of those two solvents. Choice of a particular solvent
combination will be guided by intended use of the converted
thiophene.
[0087] As mentioned previously, the invention is flexible and can
be performed by use of one or a combination of strategies.
Preferred practice of the invention involves obtaining a suitable
solvent or solvent combination and adding that solvent to a vessel.
Typically, the exchange solvent or combination is heated in the
vessel to a temperature of between from about 100.degree. C. to
about 250.degree. C. In most invention embodiments, the vessel
conditions further include exposing the solvent to a pressure of
about 1 atm, although greater or less pressures may be more
suitable for other applications.
[0088] Subsequently, about 1 part of the mixture comprising the
optionally substituted mono- or polythiophene to at least about 2
parts heated solvent per minute. Preferably, the addition step
further includes adding about 1 part of the mixture to between from
about 2 to about 10,000,000 parts heated solvent per minute,
preferably about 3 to about 100 parts of the heated solvent per
minute. Preferred contact between the heated solvent (large volume)
and the mixture (smaller volume) moves heat quickly into the
mixture sufficient to make the water vapor. In this example of the
invention, the larger solvent volume (relative to the mixture
volume) facilitates heat transfer to the mixture and production of
water vapor.
[0089] In a preferred embodiment, it is helpful to collect the
water vapor from the mixture as a condensate or distillate
separated from the vessel. Preferably, a chamber or trap is used to
catch and retain the condensed water vapor. The trap can be
configured with a cooling apparatus such as a cooling condenser to
assist condensation of the water vapor if desired. In embodiments
in which the trap is used, it is possible to measure the amount of
water collected, thereby allowing quantitation of the water vapor
captured from the mixture entering the vessel. This feature of the
invention provides many advantages eg., it allows the invention
user to monitor the amount of water removed from the system as the
solvent exchange process occurs. Moreover, the user can control the
duration and extent of water solvent removal eg., by adjusting the
heat of the exchange solvent and/or flow of the mixture into the
reaction vessel. Thus, the user can readily quantify solvent
replacement by simple inspection of the water collected in the
trap. The precise amount of water removed from the mixture as vapor
will vary depending e.g., on the intended use for the converted
mixture. Preferably, less than about 100% (w/v) of the water is
removed from the mixture as vapor, more preferably, between from
about 1% (w/v) to about 95% (w/v) of the water is removed.
[0090] Specific adaptations of the foregoing methods can facilitate
the solvent exchange process. For example, it will often be very
helpful to provide conditions of high sheer mixing between the
thiophene mixture and the exchanging solvent. Preferred conditions
reduce or prevent agglomeration (congealing) of the Baytron.TM. P
beyond a particle size of about 1 micron. Many Baytron.TM. P
formulations are provided as dispersions in which each particle has
a size of about 1 micron. In embodiments in which the high sheer
mixing conditions are employed, presence of unsuitably large
particles and agglomerates can be reduced or avoided. The converted
Baytron.TM. P formulations can have much better uniformity. A wide
variety of mixing implementations can be used to provide such high
sheer mixting conditions. Specific examples of such implementations
are provided below.
[0091] In more specific example of this invention embodiment, the
method further includes contacting the heated solvent with at least
one non-reactive gas. That gas is typically added to the vessel as
a flow or jet stream to facilitate removal of the water solvent
from the mixture. Preferably, the gas flow is configured to assist
movement of vaporized water toward a chamber or trap as described
below. Examples of suitable gases include nitrogen, a noble gas
(He, Ar, ect.); or a mixture thereof. If desired, the gas can be
pre-heated to about the temperature of the heated solvent to
minimize cooling of the solvent in the vessel. The gas can be added
to the vessel in several ways including use of a gas pump. The
volume of gas introduced into the vessel will vary with intended
use but will generally be sufficient to provide for good removal of
water vapor from the vessel into the chamber or trap.
[0092] After a desired amount of the water is replaced by the
exchange solvent or solvent combination, the converted thiophene
mixture is collected from the vessel generally as a dispersion. In
a particular example of the invention, the dispersion will
essentially consist of NMP and Baytron.TM. P; or DMAc and
Bayton.TM. P. Such dispersions according to the invention are
well-suited for the uses disclosed herein including those specific
applications intended for Baytron.TM. formulations. If needed, the
solvent exchange methods of this invention can be repeated e.g,.
one, two or three times, with the already converted thiophene
mixture to introduce one or more other desired solvents therein
including combinations of the same or different solvents.
[0093] A more specific solvent exchange method according to the
invention involves exchanging di-methylacetimide (DMAC) or
N-methylpyrrolidone (NMP) for water in a colloidal water dispersion
that includes at least one poly-3,4-ethylene dioxythiophene
preparation. An example of a preferred preparation is Baytron.TM.,
preferably Bayton.TM. M P. In one invention embodiment, the method
includes at least one and preferably all of the following
steps:
[0094] a) heating an amount di-methylacetimide (DMAC) or
N-methylpyrrolidone (NMP) in a first vessel to a temperature of
between from about 100.degree. C. to about 250.degree. C.,
[0095] b) contacting the heated di-methylacetamide (DMAC) or
N-methylpyrrolidone (NMP) with an amount of the colloidal water
dispersion comprising water and poly-3,4-ethylene dioxythiophene,
wherein the dispersion is added to the surface of the heated
solvent at a rate of between from about 0.1 to about 1000
mls/minute, preferably about 1 to 100 mls/minute, more preferably
about 10 mls/minute, the contact being sufficient to remove at
least part of the water from the dispersion as vapor; and
[0096] c) exchanging the water removed from the dispersion as vapor
with the di-methylacetamide (DMAC) or N-methylpyrrolidone
(NMP).
[0097] In one embodiment of the foregoing method, that method
further includes removing at least part of the water from the
vessel as vapor. If desired, that water vapor can be collected or
condensed into a second vessel (ie. chamber or trap) that includes
at least one co-solvent. The co-solvent can be the same or
different from the exchange solvent used in the vessel. In this
invention example, the method further includes condensing the water
vapor into a second vessel comprising at least one co-solvent.
[0098] As mentioned, it is usually desirable to maximize contact
between the exchange solvent (or solvent combination) and the
mixture comprising the poly-3,4-ethylene dioxythiophene
preparation. For example, the ratio of the amount of the
di-methylacetimide (DMAC) or N-methylpyrrolidone (NMP) solvent to
the amount of the mixture is desirably more than one, preferably
between from about 1.5 to about 10,000,000 or more, more preferably
between from about 2 to about 10.
[0099] In a preferred example of the method, the optionally
substituted poly-3,4-alkylene dioxythiophene is obtained as a
colloidal water dispersion, preferably also including at least one
counter ion. More preferably, the counter ion is polystyrene
sulfonic acid and the optionally substituted poly-3,4-alkylene
dioxythiophene is poly-3,4-ethylene dioxythiophene. A particular
example of such as polydioxythiophene is Baytron.TM. P.
[0100] Particular methods according to the invention involve
forming a composition from the mixture, preferably a conductive
coating composition therefrom, and subjecting that composition to
at least one drying step, preferably after step c) (solvent
exchange step) of the methods discussed above. Typically, formation
of the composition involves isolating that material from the vessel
used to conduct the method, for instance, by filtration,
centrifugation and the like.
[0101] The invention is compatible with a wide spectrum of drying
treatment steps so long as they facilitate production of
compositions with at least good resistivity. By the phrase "good
resistivity" is meant a resistivity of between from about 0.1 to
about 1 (ohm-cm), eg., about 0.2 to about 0.6 (ohm-cm), for
compositions having a thickness of between from about 10 nm to
about 250 nm, preferably about 40 nm to about 150 nm. Additionally
preferred drying treatment steps provide a good surface resistance
ie., between from about 100 to about 10,000 (ohm/sq), preferably
about 200 to about 650 (ohm/sq) for compositions having a thickness
of between from about 10 nm to about 250 nm, preferably about 40 nm
to about 150 nm. Still further preferred drying treatments provide
compositions with good optical transmission properties, that is, at
least about 70%, preferably at least about 90% between about 300 nm
and 600 nm when compared with a suitable control, eg.,
Baytron-P.
[0102] More particular conductive coatings of the invention include
at least one of the compositions disclosed herein, typically one,
two or three of such compositions, preferably one of same having at
least one of the following characteristics. 1) a resistivity of
between from about 0.1 to 1 (ohm-cm); 2) a surface resistance of
between from about 100 to about 10,000 (ohm/sq); 3) a thickness of
between about 10 nm to about 250 nm; and 4) an optical transmission
of at least about 90% between about 300 nm and 600 nm wavelengths.
More preferred compositions exhibit at least two of such features,
even more preferably all three of same.
[0103] It will be apparent that it is possible to relate
resistivity and surface resistance, particularly for those
compositions disclosed herein provided as coating compositions. In
general, the relationship between resistivity and surface
resistance is defined by the following mathematical formula:
Resistivity=Pie/(1n 2)*k*t*(V/I),
[0104] wherein, V (measured voltage)/I (applied current) is the
surface resistance with the unit of ohm/square for the four point
probe measurement technique, Pie/(1n 2) is a constant, k is the
geometrical correction factor (related to film thickness, probe
spacing and sample size) and t is the film thickness.
[0105] As discussed, the invention is compatible with a wide
variety of suitable drying treatments. For example, and in one
embodiment, the drying treatment includes subjecting a composition
of the invention, preferably a coating composition, to a
temperature of from between about room temperature (25.degree. C.)
to about 200.degree. C. for less than about a day (24 hours). As
mentioned previously, methods of the invention can include, if
needed, at least two drying treatment steps the same or different.
More specific drying treatments include subjecting the composition
to from between about 50.degree. C. to about 150.degree. C. for
less than about 12 hours, preferably about 80.degree. C. for less
than about 5 hours, typically about an hour or less eg., from about
1 to about 15 minutes.
[0106] In a more specific embodiment, the drying treatment includes
subjecting the coating composition to room temperature (25.degree.
C.) for less about two hours or less followed by treatment at about
80.degree. C. for between from about 1 to about 15 minutes.
[0107] Preferably, the composition has a thickness of from between
about 50 nm to about 1000 nm, preferably from between about 60 nm
to about 750 nm.
[0108] As also discussed, the invention also provides compositions
made in accord with the solvent exchange methods disclosed herein.
An example of such a composition is an optionally substituted
mono-3,4-alkylene dioxythiophene or poly-3,4-alkylene
dioxythiophene. Preferably, that composition has between from about
1% (w/v) to about 100% (w/v) di-methylacetimide (DMAC) or
N-methylpyrrolidone (NMP). Preferably, the he optionally
substituted mono-3,4-alkylene dioxythiophene is mono-3,4-ethylene
dioxythiophene commercially available as Baytron.TM.. Also
preferably, the optionally substituted poly-3,4-alkylene
dioxythiophene is poly-3,4-ethylene dioxythiophene commercially
available as or Baytron.TM. P.
[0109] Preferred compositions according to the invention can also
include at least one additive such as those particular additive
disclosed previously. An example of such an additive is ferric
toluene sulfonic acid (Baytron.TM. C). Preferably, the ferric
toluene sulfonic acid is present in the composition in trace
amounts.
[0110] In some embodiments, it will be desirable to combine the
compositions of this invention with at least one additive. Suitable
organic, polymeric binders and/or organic, low-molecular
cross-linking agents may also be added to the coating solutions
according to the invention. Appropriate binders are described, for
example, in EP-A 564 911. Epoxysilanes, such as those provided by
the EP-A 564 911 application, can be added to the coating solutions
according to the invention, particularly for the production of
adhesive layers on glass.
[0111] Particular converted polydioxythiophene compositions are
preferably used in what is known in the field as a dispersion or
solution in a cationic form. That is, a form in which those
compositions are obtained, for example, by treating the thiophenes
with oxidizing agents. Known oxidizing agents, such as potassium
peroxodisulphate are typically used for the oxidation. Also
typically, oxidized mono- and polydioxythiophenes acquire positive
charges. These charges are not shown in Formulae I and II above,
since the number and positions of such charges are not needed to
understand and appreciate the invention.
[0112] More specific polydioxythiophene compositions according to
the invention contain, based on the sum of polythiophene cations
and polyanions, that is, based on the total solids content of the
solution, from 1 to 100,000% by weight, preferably 10 to 1,000% by
weight, of the compounds of Formulae I and II including hydroxy and
carboxyl groups. More preferred compositions of this invention are
water soluble.
[0113] As also discussed, the invention features a wide spectrum of
compositions particularly in coating or film formats. Preferred
coating compositions include at least one of the foregoing
converted (solvent exchanged) optionally substituted
polythiophenes, and at least one suitable organic polymer,
co-polymer or mixture thereof. Methods for adding such polymers to
the converted polythiophenes are known in the field and are
exemplified below. Suitable polymers, co-polymers and mixtures
include, but are not limited to, polycarbonate, polystyrene,
polyacrylates, polyesters such as polyethylene terephthalate,
polybutylene terephthalate, polyethylene naphthalate, polyamides,
polyimides, optionally glass-fibre reinforced epoxy resins,
cellulose derivatives such as cellulose triacetate, polyolefins
such as polyethylene, polypropylene. Examples of preferred
polyimides for use in preparing the films include TOR-NC (Triton
Systems, Inc.), Matrimid (1,3-isobenzofulrandione,
5,5'-carbonylbis-polymer with 1 (or 3)-(4-aminophenyl)-2,3
dihydro-1,3,3 (or 1I1,3)-trim 5-amine) (Ciba); and Aurum (Mitsui
Toatsu). The TOR-NC has a chemical structure represented by the
following Formula III: 3
[0114] More preferred coatings and films of the invention are
conductive and include a weight ratio of at least one of the
converted thiophene to the foregoing polymers, co-polymers, graft
co-polymers (eg., TOR-NC, Matrimid, Aurum, or a mixture thereof) is
about 10:90 to about 0.1 to 99.9, preferably 6:94 to about
0.5:99.5. A preferred film composition is the TOR-NC polyimide and
converted Baytron.TM. P formulation (TOR-CP, see below). Other
polyimides and/or polydioxythiophene combinations may be better
suited for other applications.
[0115] In invention embodiments in which the Baytron.TM. P
polydioxythiophene (or polythiophene made from Baytron.TM. M) has
at least about 90% (w/v) of the water solvent exchanged with NMP or
DMAc, preferably at least about 95% (w/v) of the water solvent
exchanged with NMP or DMAc, and more preferably at least about 99%
(w/v) up to 100% (w/v) so exchanged, the converted Baytron.TM.
formulation will often be referred to herein as TOR-CP (Triton AO
Resistant Conductive Polymer made from Baytron.TM. P).
[0116] More preferred coating films made from TOR-CP include
between from about 0.5% (w/w) to about 5% (w/w) of the TOR-CP
relative to the polyimide of interest, preferably between from
about 1% (w/w) to about 4% (w/w). See the Examples below as well as
the Drawings.
[0117] Preferred coating materials of the invention include from
about 1 mg/m.sup.2 to about 500 mg/m.sup.2 of at least one of the
compositions of this invention including TOR-CP exchanged with NMP
or DMAc. The TOR-CP can include one or more polyimides of interest
including at least one of Matrimid and TOR-NC. Of course, other
compositions as disclosed herein may be more suitable for other
applications. Additionally preferred coating materials have an
optical density of between from about 0.0001 to about 0.05 at
between from about 300 nm to about 700 nm. Also preferred are those
coating materials that exhibit light transmission of between from
about 10% to about 95% or more, preferably 80% to about 99% or more
as measured by a BYK Gardner Haze-gard plus machine. Such coating
compositions will often further include at least one additive as
described previously. Coating compositions having a light
transmission greater than about 80% will often be preferred in many
optical applications.
[0118] The compositions of this invention including preferred
conductive films and coatings can be produced by reference to
recognized processes disclosed in U.S. Pat. Nos. 5,766,515,
6,083,835, 5,300,575, and 6,157,479. Preferred production processes
involve, for example, spraying, application by a doctor blade,
dipping, application with roller applicator systems, by printing
processes such as gravure printing, silk screen printing, curtain
casting, and can be dried at room temperature or at temperatures of
up to 300.degree. C., preferably up to 200.degree. C. Suitable
substrates are transparent substrates such as glass or plastic
films (e.g. polyesters, such as polyethylene terephthalate or
polyethylene naphthalate, polycarbonate, polyacrylate, polysulphone
or polyimide film).
[0119] The invention has other applications as well. For example,
the compositions, films and coatings disclosed herein can be used
to coat some or all of an organic or inorganic fiber or related
substrate. Illustrative of such fibers include those made whole or
in part from Kevlar.TM. (aramide), polyethylene, PBO
(poly-benzoxazol), polyester, nylon, polyamide, glass; as well as
combinations thereof. Preferred fibers are about 0.5 to 50 deniers,
preferably about 1 to about 10 deniers. Application of the
invention compositions, films and coatings will help improve the
electrical conductivity of the fibers.
[0120] The invention is also compatible with techniques for making
spin-coated filaments, particularly monofiliments, by
electrospinning. See Reneker, D. H. Nanometer Diameter Fibres of
Polymer Produced by Electrospinning, Fourth Foresight Conference on
Molecular Nanotechnology.
[0121] For some applications, it will be useful to anneal the films
and coatings e.g, to increase electrical conductivity. Methods for
annealing a wide variety of suitable films and coatings have been
disclosed in the U.S. Pat. No. 6,083,635, for example.
[0122] The coatings and films of this invention can be used in a
variety of thicknesses depending, eg., on intended use and desired
transparency and conductivity parameters. A preferred thickness is
from about 0.005 to about 500 .mu.m, preferably from about 0.05 to
about 10 .mu.m. Preferred conductive coating materials of this
invention can be configured as a layer having a surface resistance
of between from about 10.sup.0 to about 10.sup.12 .OMEGA./sq.
Additionally preferred are coatings featuring a surface resistance
of from about 0.1 to about 2000 .OMEGA./sq, preferably from 1 to
300 .OMEGA./sq.
[0123] As disclosed herein and in the prior provisional application
06/269,606 filed on Feb. 16, 2001, a wide spectrum of organic
solvent-based conducting polymer systems, particularly TOR-CP.TM.
has been provided. Tor-CP is PEDOT:PSS based organic solvent
systems, such as NMP, which has a very low water content of less
than 3% water. The present invention is further investigation of
the Tor-CP-based coatings for the electro-optic device
applications. Electrical resistivity measurement results indicated
that coatings produced using Tor-CP exhibited higher electrical
conductivity than that of the state-of-the-art conducting polymer
systems such as PEDOT:PSS supplied by Bayer A G (trade name
Baytron-P). Furthermore, optical transparencies of the coatings
using Tor-CP are similar to that of the Baytron-P. In addition,
resulting coating are very stable in the ambient laboratory
atmosphere. Applicants have not observed any degradation of coating
properties during exposure to unprotected ambient atmosphere longer
than one month. During the same period, coatings prepared using the
Baytron-P and stored in the same environment degrades (seriously
softened), probably due to reaction with moisture.
[0124] Excellent electric conductivity, high optical transparency
and environmental stability of the coatings from Tor-CP suggest
that Tor-CP is an ideal candidate material for many electro-optic
device applications. Furthermore, low water contents in the Tor-CP
will provide additional benefit of ease-of manufacturing of
electro-optic devices that contain ITO electrodes. In addition,
non-acidic and non-hygroscopic natures of the coatings from Tor-CP
further suggest a long lifetime or less performance degradation of
the devices fabricated using Tor-CP. The unique properties of the
coatings from Tor-CP further suggest that present transparent
electrodes of ITO can be replaced by coating from Tor-CP for a
certain applications. In such case, all organic material based
electro-optic devices can be realized, including flexible plastic
(or polymer) substrates that will significantly reduce
manufacturing costs of many electro-optic devices and provide
opportunities of producing advanced electro-optic devices that
requires flexible substrates.
[0125] Furthermore, the electric conductivity of the Tor-CP
coatings can be significantly increased without degrading the
optical transparency by employing specially designed coating
fabrication processes.
[0126] The conductive films and coatings according to the invention
find use in a wide range of applications requiring good electrical
conductivity e.g., as electrodes in electroluminescent displays, in
LCD displays, in solid electrolyte capacitors, for the deposition
of metals such as copper, nickel, for example, in the manufacture
of printed circuits, in solar cells, in electrochromic displays or
for the screening of electromagnetic radiation or for leading away
electrical charges, for example, in picture tubes or as
anticorrosive coatings on metals, for the production of touch
screens. Other areas of application are systems for picture
production, for example, silver halide photography, dry-plate
systems, electrophotography.
[0127] The conductive coatings and films of the invention are
well-suited for optional coating with further layers such as those
reported in the U.S. Pat. No. 6,083,635, for example.
[0128] Also provided by the present invention are articles of
manufacture that include or consist of at least one of the
compositions disclosed herein. Examples of such articles include,
but are not limited to, an antiradiation coating, antistatic
coating, battery, catalyst, deicer panel, electrochromic window,
electrochromic display, electromagnetic shielding,
electromechanical actuator, electronic membrane, embedded array
antenna, fuel cell, infrared reflector, intelligent material,
junction device (PV), lithographic resist, non-corrosive paint,
non-linear optical device, conductive paint, polymer electrolyte,
radar dish, redox capacitor, sealant, semiconductor circuit,
sensor, smart window, telecom device, waveguide, or wire (low
current). Preferably, the electromechanical actuator is one of a
biomedical device, micropositioner, microsorter, microtweezer, or
microvalve. Also preferably, the sensor is one of a biological,
chemical, electrochemical, irradiation dosage, mechanical shock,
temperature, temperature limit, or time-temperature sensor.
[0129] As discussed, many electro-optic devices, such as light
emitting diodes (LED's) and photovoltaic cells, require
electrically conductive and optically transparent films/coatings as
electrode materials. Presently, transparent electrodes in
electro-optic devices are made of ITO coated glass substrates. ITO
has, however, several crucial shortcomings. Its manufacturing
processes involve a relatively cumbersome and costly technology,
such as vacuum deposition in a controlled gas atmosphere.
Furthermore, due to brittle-nature of the ITO films, it is
difficult to prepare the ITO films on large area substrates or
flexible substrates.
[0130] Currently, transparent conducting polymers and their
coatings are considered the best candidate material as a hole
injection layer in organic light emitting diodes (OLED's). In this
application, a thin layer (less than 20 nm thickness) of
transparent conducting polymers is deposited by employing a
solution film casting process, such as a spin-coating method, onto
the ITO coated substrate. As previously mentioned, the ITO layer is
deposited onto the rigid substrate, such as glass, via a vacuum
deposition process. Since the ITO is very sensitive to moisture and
other acid based chemicals, fabricating a hole injection layer on
top of ITO requires cumbersome processes and serious limits the
selection of substrate materials.
[0131] Although electrically conductive and optically transparent
coatings have been successfully produced using polyaniline (PANI)
containing solution (U.S. Pat. No. 5,618,469) and PEDET/PSS polymer
dispersion (Eur Patent 686662), these prior art inventions have
serious limitations in manufacturing practical electro-optic
devices. For example, it is well known that the PANI systems are
not stable and, therefore, it's device performance degrades rapidly
over time. Performances of the carefully fabricated PEDOT:PSS-based
devices are known to be stable in use. However, currently available
PEDOT:PSS polymers are an aqueous based system. Therefore,
fabricating PEDOT:PSS coatings onto ITO coated substrates requires
cumbersome manufacturing processes. Further hydrophilic nature of
the PEDOT:PSS system attracts moisture, even through the protective
moisture barrier, and can induce premature failure of the devices
during use.
[0132] As mentioned previously, additional articles of manufacture
in accord with the invention include or consist of at least one
electro-optical implementation eg., one, two, three or more of
same. Preferred implementations include organic light emitting
devices (OLEDs), electro-optical switches, photovoltaic cells and
the like.
[0133] In preferred embodiments, the OLED includes at least one and
typically all of the following components operatively linked
together: 1) metal cathode; 2) electron transport layer (ETL); 3)
organic emitter; 4) hole injection layer (HIL); and 5) a glass
substrate layer. Optionally, the OLED further includes an indium
doped tin oxide (ITO) anode operatively linked to the same. A
representation of such an OLED structure has been reported by
Cropper, A.D. et al. in Organic Light-Emitting Materials and
Devices IV, Kafafi, Z. H. Editor, Proceedings of SPIE, Vol. 4105
18-29 (2001). See FIG. 2 of Cropper, A. D. et al. entitled "OLED
basic structure" in particular. By the phrase "operatively linked
together" is meant association of such components in a
configuration necessary to achieve suitable functionality of the
OLED.
[0134] It is an object of this invention to replace the ITO of the
OLED with at least one of the compositions disclosed herein,
preferably one of the conducting compositions. This feature of the
invention provides advantages including better performance
characteristics, especially improved conductivity and optical
transparency. Preferred OLEDs of the invention will include at
least one of the compositions disclosed herein provided as the hole
injection layer (HIL). An especially preferred OLED includes TOR-CP
as the HIL.
[0135] In a more particular example of the invention, the OLED has
a peak external quantum efficiency of between about 0.02% to about
0.2%, preferably when such OLED is operated between from about 4 to
about 8 volts.
[0136] Additionally preferred OLEDs of the invention have a peak
power efficiency of between from about 0.5 to about 2 lm/W at an
applied bias of between from about 1 to about 8 volts.
[0137] Still further preferred OLEDs have a luminance of between
about 7000 to about 9000 cd/m.sup.2. Preferably, the OLED has a
maximal luminance of between from about 10,000 to about 50,000
cd/m.sup.2 at about 4 to about 8 volts.
[0138] As mentioned the invention also provides suitable methods
for making an electronic implementation by writing or printing
manipulations. Preferably, such methods are performed repetitively
or semi-repetitively e.g., as when at least step a) is repeated at
least once. In a particular method steps a), b) and c) are repeated
twice or more to print or write the electronic implementation.
[0139] In other preferred embodiments of the method, the hole
(via-hole or interconnect) produced by dissolution of the first
polymer layer by the exchange solvent in the composition includes a
first end contacting the first polymer layer and a second end
contacting a substrate layer. That hole is substantially filled
with the composition according to the method, preferably with the
assistance of a conventional ink-jet printer. One suitable ink-jet
printer includes at least two nozzles for dispersing the
composition of the invention, each nozzle comprising the same or
different composition as needed. Preferably, at least one of the
compositions comprises poly(3,4-ethylenedioxy-thiophene) which
composition may further include polystryene sulfonic acid
(PEDOT/PSS). A more preferred composition for use with the method
for making the electronic implementation is Baytron.TM.-P or a
suitable polymer of Baytron.TM.-M.
[0140] In one embodiment of the method for making the electronic
implementation, the first polymer layer comprises or consists of a
dielectric polymer e.g., polyvinylphenol, polyimide and
polycarbonate. Preferably, the substrate layer is insoluble in the
solvent of the composition. An exemplary substrate is glass.
[0141] In another invention example, the electronic implementation
produced by the method is an inverter capable of converting a
high-voltage input to a low-voltage output; or a low-voltage input
to a high-voltage output. Methods for making and using inverters
have been described. A more preferred inverter is a component of an
electronic circuit which circuit comprises at least one source
electrode and at least one drain electrode. Typically, such
electrodes are separated from each other by about 1 to 10
micrometers. See e.g,. Dagni, R. in Chemistry and Engineering, Jan.
1, 2001, pp. 26-27 as well as references cited therein.
[0142] The invention methods can also be used to make useful
electronic circuits having a preferred output of between from about
-20V to about 0V. Additionally useful electronic circuits have as
an input between from about 0V to about -20V. Methods for making
and using electronic circuits have been described. See e.g., the
website at plasticlogic.com as well as references cited therein,
the disclosure of which is incorporated herein by reference.
[0143] As mentioned, the invention also provides articles of
manufacture that include the electronic implementations of this
invention. Exemplary articles include a liquid crystal display,
electrophoretic ink display, polymer disperse liquid crystal (PDLC)
or an identification tag such as a smart label adapted for use in
consumer good. Particular examples of such consumer goods include s
a toy or supermarket item.
[0144] In particular invention embodiments, electrically conductive
and optically transparent organic solvent based polymer coatings
are provided. Also provided are methods for the preparation of the
same for applications of which flexibility and environmental
stability are of an important consideration.
[0145] In addition, the present invention also relates to a method
for preparing coatings of organic solvent based
poly(ethylenedioxythiophene):- poly(styrene sulfonic acid)
(PEDOT:PSS) conducting polymers for improved properties, such as
electrical conductivity, of the resulting coatings for use in
electro-optic devices comprising transparent electrodes which are
made of same. In this embodiment the organic solvent-based
polymeric system does not have compatibility problems with the
state-of-the-art transparent conductive layer of indium doped tin
oxides (ITO). Therefore, manufacturing processes of electro-optic
devices can be easier. Furthermore, high conductivity and optical
transparency of the resulting films from the organic solvent based
conducting polymer system suggest a possibility of replacing the
ITO layer in many electro-optic device applications such as organic
light emitting diodes (OLED's), photovoltaic cells, electro-optic
switches, etc.
[0146] As shown in the Example 8, below, a thin layer (less than 20
nm thickness) of transparent conducting polymers is deposited by
employing a solution film casting process, such as a spin-coating
method, onto the ITO coated substrate. As previously mentioned, the
ITO layer is deposited onto the rigid substrate, such as glass, via
a vacuum deposition process. Since the ITO is very sensitive to
moisture and other acid based chemicals, fabricating a hole
injection layer on top of ITO requires cumbersome processes and
serious limits the selection of substrate materials.
[0147] Additionally preferred conductive coatings in accord with
the invention feature a surface resistance of between about 10
ohm/sq to about 1000 ohm/sq when spin-coated in less than about 10
layers, preferably less than about 5 of same, more preferably about
1, 2 or 3 of such layers. Preferred spin-coated layers are less
than about 10 mil thick, more preferably about 5 mil thick although
thinner layers may be more appropriate for some invention
applications.
[0148] Further preferred conductive coatings have a light
transmittance of at least about 80%, preferably greater than about
85%, more between from about 86% to about 95% as determined by
conventional procedures disclosed herein. Additionally preferred
conductive coatings exhibit such favorable light transmission
properties when spin-coated in less than about 10 layers,
preferably less than about 5 of same, more preferably about 1, 2 or
3 of such layers. Preferred spin-coated layers are less than about
10 mil thick, more preferably about 5 mil thick although thinner
layers may be more appropriate for some invention applications.
Such preferred conductive coatings have a wide variety of
applications including use as an anode electrode. See Example 9 and
FIGS. 14-14, for instance.
[0149] In embodiments in which the anode electrode includes (or
consists of) one or more of the conductive coatings disclosed
herein, such an electrode will feature a surface resistance of less
than about 5 kohm/sq, preferably less than about one kohm/sq to
about two kohm/sq. Additionally preferred electrodes have an
optical transmission of at least about 85%.
[0150] Additionally preferred conductive coatings in accord with
the invention exhibit favorable resistivity and conductivity when
featured on an Ln-Ln conductivity graph. See Example 10 and FIGS.
16 and 17. Particular coatings exhibit at least about 1 Ln-sigma
(S/cm), preferably between from about 1 Ln-sigma (S/cm) to about 10
Ln-sigma (S/cm), more preferably between from about 1 Ln-sigma
(S/cm) to about 4 Ln-sigma (S/cm). Further preferred conductive
coatings feature such good conductivity at high temperatures of
between from about 0.01 Ln-Temp (K.sup.-1/2) to about 0.2 Ln-Temp
(K.sup.-1/2).
[0151] Still further preferred conductive coatings do not exhibit
what is known as a "kink", particularly between about 0.05 Ln-Temp
(K.sup.-1/2) to about 0.1 Ln-Temp (K.sup.-1/2), preferably between
from about 0.06 Ln-Temp (K.sup.-1/2) to about 0.08 Ln-Temp
(K.sup.-1/2). See Example 10 and FIG. 17.
[0152] Additionally preferred conductive coatings of the invention
exhibit good conductivity ie., at least about 1 Ln-sigma (S/cm),
between from about 0.1 Ln-Temp (K.sup.-1/4) to about 0.5 Ln-Temp
(K.sup.-1/4), preferably from about 0.2 Ln-Temp (K.sup.-1/4) to
about 0.35 Ln-Temp (K.sup.-1/4). Also preferred are conductive
coatings that do not exhibit the "kink" between about 0.2 Ln-Temp
(K.sup.-1/4) to about 0.4 Ln-Temp (K.sup.-1/4), preferably between
from about 0.24 Ln-Temp (K.sup.-1/4) to about 0.3 Ln-Temp
(K.sup.-1/4). See Example 10 and FIG. 17.
[0153] The following examples are provided to point out preferred
aspects of the invention and are not intended to be indicative of
the scope of the invention.
EXAMPLE 1
Solvent Exchange Process for Making TOR-CP/NMP
[0154] The following are preferred processes for making TOR-CP
using N-methylpyrrolidone (NMP) as the exchange solvent.
[0155] A. Method 1
[0156] 1. Place the Ace Glass 22L RB 4 neck flask into the Glas-Col
heating mantle canister
[0157] 2. Take the Ace Glass 19 mm stir shaft w/teflon paddle
assembly and place into the center neck of the 22 L RB flask,
followed by the teflon lined stirrer bearing
[0158] 3. Attach the stirrer shaft to the chuck of the Arrow 850
stirrer motor
[0159] 4. Hookup the SGA variac controllers to the Glas-Col heating
mantle canister
[0160] 5. Attach the Dean Stark Trap to the left neck of the 22 L
flask, then place the Ace Glass 300 mm coil condenser on top of it.
A tube will then run from the top of the condenser to the nitrogen
bubbler.
[0161] 6. In the right neck of the 22 L flask, place the teflon
coated temperature probe and the nitrogen line supplied by the
Gilmont instruments flowmeter.
[0162] 7. Into the front neck of the 22L RB flask, charge with
10,504 ml of NMP (water miscible solvent as described above)
[0163] 8. Turn on the SGA variacs and heat the solvent to 135 C
under agitation from the Arrow 850 stirrer motor. The stirrer
setting (rpm) should not need to be changed throughout the
remainder of the process
[0164] 9. Set the Gilmont Instruments nitrogen flowmeter to produce
a steady flow of nitrogen through the flask until it comes out the
bubbler
[0165] 10. Using the Watson-Marlow peristaltic pump, begin pumping
3000 ml of Baytron P into the 22 L RB flask at a flow rate of 10
ml/minute
[0166] 11. Continue pumping the Baytron P into the reactor vessel
until complete (approx. 3 hrs)
[0167] 12. As the Baytron P is being fed into the reactor, water
should start condensing and collecting in the Dean Stark trap
[0168] 13. At this point, adjust the nitrogen flow meter to
increase the nitrogen flow considerably, forcing the water vapor up
into the coil condenser
[0169] 14. The water will start to rapidly condense and collect in
the Dean Stark trap. Drain the trap as needed.
[0170] 15. Continue this process until the desired amount of water
has been removed.
[0171] 16. Shut of the variacs, continue the agitation and the
nitrogen flow until the product in the flask has cooled to RT
[0172] 17. Remove from product from the flask
[0173] B. Method 2
[0174] As discussed, it will often be helpful to provide conditions
of high sheer mixing between the thiophene mixture and the
exchanging solvent. Such conditions can facilitate a reduction in
particle agglomeration and provide for better product uniformity.
High sheer mixing can be readily practiced by replacing the 4 neck
flask in Method 1 (step 1) with a five neck flask. Between steps 7
and 8, for example, the reagents can be subjected to high sheer
mixing by using a standard homogenizer or disperser. A preferred
homogenizer is a Model #T 25 Ultra-Turrax Disperser/Homogenizer
(IKA-Works). Optimal use of the homogenizer will keep Baytron P
particles from agglomerating as determined eg., by inspection.
EXAMPLE 2
TOR/CP Conductive Coatings
[0175] Three types of conductive coatings have been made using the
solvent exchange process of this invention.
[0176] A. TOR-CP Spin-Coating
[0177] A conductive coating was made from the solvent exchanged
TOR-CP/NMP (neat) composition prepared as described above in
Example 1. Specifically, the composition was spin-coated onto a
glass substrate using conventional procedures. Conductivities were
measured with a Keithly 200 4 point probe.
[0178] FIG. 1 shows light transmission and surface resistance data
when TOR-CP (unfiltered), TOR-CP (filtered), and Baytron-P
converted products were tested. As can be seen from FIG. 1,
coatings made from the TOR-CP have better light transmission and
lower surface resistance then the Baytron-P coating. FIG. 1 was
prepared from measurements made of TOR-CP (neat) dispersion cast
onto glass. Although this is technique is suitable for some
applications, it will often be useful to combine the TOR-CP with
other components and particularly at least one polymer, co-polymer,
polymer blend, ect. In many instances, the resulting film or
coating will have better performance characteristics when compared
to TOR-CP alone.
[0179] B. TOR-CP Draw Down Coatings
[0180] Standard draw down techniques were used to apply the TOR-CP
to a glass substrate. Such techniques have been described e.g, by
Erichsen. Specifically, the Erichsen Testing Equipment product
brochure describes such techniques.
[0181] This composition was coated onto glass substrates using an
Erichsen Model 360 film application. Wet film thickness of 120
microns was applied and the dry film thickness for the TOR-CP
samples was between 0.3 to 0.5 microns. See FIG. 6.
[0182] Additional drawdown coatings using the Baytron.TM. P product
were made in order to compare the surface resistance to each other.
The surface resistance measurement was made by applying silver
electrodes to the coating using IEC standard 93 (VDE 03003) and
measuring resistance with an ohmmeter. The resulting resistance was
expressed as ohm/sq. See FIG. 6.
[0183] It is significant that the surface resistance of the TOR-CP
coatings was up to two orders of magnitude less resistive (ie. more
conductive) than similar Baytron.TM. P coatings. This indicates
that the conversion (solvent exchange) process boosts the
conductivity of the base conductive polymer in an unexpected way
and significantly improves the performance of the resulting TOR-CP
material. See also FIGS. 7A, 7B, and 7C (showing data from selected
samples of Baytron.TM. P exchanged with NMP or DMAc). Drawdown
surface resistances are also illustrated.
[0184] C. Formulated TOR-CP Coatings
[0185] Formulated TOR-CP coatings according to the invention can be
applied using spin-coating or draw down procedures.
[0186] One method for making a formulated conductive coating is as
follows. Referring to Table 1, below, listed components were
combined (wt % ratios) and mixed in the order given. Mixing under
constant agitation was preferred.
1 TABLE 1 Component Manufacturer % by Weight TOR-CP Triton Systems
45 Silquest A 187 Witco Surfactants GmbH 0.86 Isopropanol 53.84
Bayowet FT 229 Bayer Corp 0.30 Total 100
[0187] A coating made by this method can be applied to substrates
using standard spin coating or draw down coating techniques. See
sections A and B, above. The coating was prepared in a glass vessel
with paddle stir mechanism.
[0188] FIG. 8 shows surface thickness and resistance for several
TOR-CP formulated drawdown coatings. The results show favorable
conductivity using this coating method.
EXAMPLE 3
Conductive TOR-CP Films with Polyimide
[0189] Conductive polyimide films have been manufactured by adding
dry polyimide powder to TOR-CP converted (ie. solvent exchanged)
solution. See Example 1, above. Typically, the polymide powder and
TOR-CP converted materials are mixed. A preferred weight ratio
between the polyimide polymer and conductive polymer ranges from
94:6 to 99.5:0.5.
[0190] A more specific method for making the film is as follows. A
starting quantity of TOR-CP dispersion is weighed. The total
conductive polymer solids amount is determined by multiplying the
total dispersion weight by the solids content of the dispersion.
Polyimide is added to the solvent dispersion so that the final
weight ratio of the solids conductive polymer to polyimide is
either 0.5/99.9, 1.0/99 or 2.5/97.5. The polyimide is added to an
agitated TOR-CP keeping agitation with a magnetic stir bar.
[0191] Volume conductivity (ohm-cm) has been measured for films
that contain 1,2.5 and 4% conductive polymer respectively. FIGS. 2
and 3 show measurements made on blends that contain the Triton AO
resistant polyimide (TOR-NC) and a commercial polyimide from Ciba
called Matramid.
EXAMPLE 4
Analysis of Converted (Solvent Exchanged) Baytron.TM. P Batches
[0192] To better appreciate the performance characteristics of
Baytron.TM. P formulation converted according to the invention, the
following parameters were analyzed: conductivity, viscosity, solids
content, particle size and distribution, light transmission, pH
value, density and water content. Analyses were performed according
to recognized procedures. See FIGS. 4 and 5 ("MAV" numbers refer to
specific Bayton.TM. P batches).
[0193] Referring now to the particle size analysis of FIGS. 4 and
5, the data shows an average particle size ranging from <1
micron to >30 micron. Specifically shown by FIGS. 4 and 5 are
particle analysis of three of samples, and then a summary sheet
showing several properties we are monitoring. Particle Size
analysis was done by Micromeritics in Norcross Ga. The technique
used is called Eltone.TM. particle size analysis.
[0194] FIG. 6 shows conductivity measurements using Baytron.TM. P
(neat) and batches of converted (solvent exchanged) Baytron.TM. P
(MAV 92-96, 83-86 and 77). Resistances were measured according to
standard procedures. The data show that the converted Baytron.TM. P
formulations exhibited an increase in conductivity (decreased
resistance) of about two to three orders of magnitude.
Significantly, it has been found that the conductivity increase of
the converted Baytron.TM. P formulation can be achieved with a film
thickness up to about half that of the neat formulation.
EXAMPLE 5
Process for Making Conductive Films Useful In Antistat
Applications
[0195] It is possible to combine the converted (solvent exchanged)
TOR-CP solutions of this invention with a wide spectrum of suitable
polymers e.g, polyimide, polycarbonate, epoxies, polyarylene
ethers, polyester, PEN, and other solution processed polymers,
using conventional film processing methods such as those disclosed
herein. More specific examples of such polymers can be found in the
Modern Plastics Encyclopedia Vol. 75, No. 12 (Mid-November 1998
issue). Suitable procedures for blending the polymers and
conductive polymer solution (TOR-CP) are known in the field
including simple weight measurements, room temperature stirring,
etc.
[0196] Two more specific methods for making the films are as
follows.
[0197] A. Method 1
[0198] First, make a solution that essentially dissolves various
polymer into the TOR-CP dispersion. Nearly any polymer that is
soluble in the NMP solvent could be used such as polyimide,
polyesters, polyurethanes, polycarbonates, polysulfones,
polyetherimides and the like. In one application, polymer was added
to an agitated TOR-CP dispersion so that the ratio of conductive
polymer to added polymer is in the range of 0.5% to 3% by weight.
The solvent (NMP) content was then adjusted to bring the total
solids content (conductive polymer/dopant plus non-conductive base
polymer) to approximately 18%-22% by weight. The mixture was
stirred until a homogeneous honey like consistency is achieved. The
blended solution was then filtered through a 12 micron filter and
cast onto a substrate using a drawdown bar, or lip casting process.
The substrate was then passed through a heating section to drive
off the NMP solvent at about 150 C for 10-30 minutes depending on
whether this is a continuous or batch process. This process has
been practiced in both batch and continuous methods and various
data has been collected.
[0199] B. Method 2
[0200] Another way to incorporate TOR-CP would be dependent on
ability to convert the water based Baytron P into a high molecular
weight polymer instead of into a solvent. A particular material of
interest is polybutene (BP Amoco). Assuming the conductive polymer
can be incorporated into the polybutene at about 50% concentration,
then it will be possible to let that mixture down into polyolefins
during a melt processing operation. This could then open up the
possibility of making conductive polyethylene, or polypropylene
with a much lower cost melt processing technique. The temperatures
for processing this combination must be kept below 200 C to prevent
degradation to the conductive polymer dopant and this would be the
case with polyolefins.
[0201] A preferred film produced by either of the foregoing
specific methods is free standing and has a conductivity through
the thickness (instead of just at the surface) which can be from
<1 mil to >5 mils thick (1 mil=0.001"). The volume resistance
ranges from 10.sup.4-10.sup.12 ohm-cm depending, for example, on
the weight concentration of the conductive polymer. Particular
applications for such films include antistatic packaging materials,
electrostatic discharge (ESD) and electromagnetic interference
(EMI) shielding films.
[0202] The following materials were used, as needed, in the
foregoing Examples unless specified otherwise.
[0203] 22 L Round Bottom 4 neck Flask (Ace Glass)
[0204] Glas-Col Heating Mantle Canister
[0205] SGA Variac Controllers
[0206] 19 mm Glass Stir Shaft w/teflon paddle assembly (Ace
Glass)
[0207] 19 mm Teflon Lined Stirrer Bearing (Ace Glass)
[0208] Watson-Marlow Peristaltic Pump model #505DU
[0209] Arrow 850 Stirrer Motor w/chuck
[0210] 300 mm Coil Condenser (Ace Glass)
[0211] 325 ml Dean Stark Trap (Aldrich)
[0212] Teflon Coated Temperature Probe w/digital read
[0213] Gilmont Instrument Nitrogen Flowmeter
[0214] Nitrogen Bubbler
[0215] Model #T 25 Ultra-Turrax Disperser/Homogenizer
(IKA-Works)
EXAMPLE 6
Preparation of Polymer Coating Layers
[0216] Table 2, below, shows a list of representative coatings
produced during the course of the present invention. Baytron-P, an
aqueous based PEDET:PSS conducting polymer manufactured and
supplied by Bayer A G was used as a reference throughout the
experiments. Tor-CP and Baytron-P coatings were fabricated by
employing a spin-coating method with a 2000 rpm spin speed. Two and
a half inch diameter and {fraction (1/16)} inch thick borosilicate
glass disks were used as substrates throughout the experiments.
Thickness of the final coatings was controlled by applying multiple
spin-coating operations with the same spin speed and duration of
spin of 10 seconds. After each spin coating, polymer
coating/substrate combinations were dried by employing two
different drying methods as described in Table 2: (1) oven dry at
80.degree. C. for 5 minutes and (2) dry at ambient temperatures for
60 minutes followed by oven dry at 80.degree. C. for 5 minutes. All
dried samples were stored in the sealed plastic bags before
electrical conductivity/resistivity and optical
transmission/absorbance measurements.
[0217] More particularly, for spin-coating, the glass substrate was
mounted on the vacuum chuck of the spinner and 1.5 mL of Tor-CP or
Baytron-P solutions are applied in the middle of the substrate,
followed by start spinning with the preset speed of 2000 rpm and
duration of 10 seconds. Specific batch No. of the Tor-CP was KAC79
and 0.6% solid content in NMP solvent. Baytron-P is 1.3% solid
content in water solvent.
[0218] Thickness of the coating was measured using a stylus surface
profilometer.
2TABLE 2 Representative Coatings and Preparation Conditions Coating
Conducting Thickness Coating ID Polymers (nm) Drying Conditions
Baytron-P-O1 Baytron-P 120 A. 80 C. oven drying for 5 minutes
Baytron-P-O2 Baytron-P 314 80 C. oven drying for 5 minutes
Baytron-P-O3 Baytron-P 592 80 C. oven drying for 5 minutes
TOR-CP-O1 TOR-CP 52 80 C. oven drying for 5 minutes TOR-CP-O2
TOR-CP 105 80 C. oven drying for 5 minutes TOR-CP-O3 TOR-CP 171 80
C. oven drying for 5 minutes TOR-CP-A1 TOR-CP 70 RT air dry for 60
minutes and followed by 80 C. oven drying for 5 minutes TOR-CP-A2
TOR-CP 107 RT air dry for 60 minutes and followed by 80 C. oven
drying for 5 minutes
[0219] FIGS. 9A-D are explained in more detail as follows. In
particular, FIG. 9A shows measured values of electrical resistivity
of the resulting coatings as a function of coating thickness for
Baytron-P and Tor-CP coatings. For Tor-CP coatings two different
drying methods were employed as described in Table 2. Resistivity
of these coatings was measured by employing a standard four point
probe technique and calculated for the known coating thickness and
geometrical correction factor (ASTM Standard F374). Accuracy of the
measured values of resistivity using four point probe method were
confirmed by employing a Van der Pauw technique for the selected
coating at outside laboratory.
[0220] As shown in FIG. 9A for the given coating thickness,
coatings from Tor-CP exhibited at least two orders of lower
resistivity, higher electric conductivity, than that of
3TABLE 2 Representative Coatings and Preparation Conditions Coating
Conducting Thickness Coating ID Polymers (nm) Drying Conditions
Baytron-P-O1 Baytron-P 120 A. 80 C. oven drying for 5 minutes
Baytron-P-O2 Baytron-P 314 80 C. oven drying for 5 minutes
Baytron-P-O3 Baytron-P 592 80 C. oven drying for 5 minutes
TOR-CP-O1 TOR-CP 52 80 C. oven drying for 5 minutes TOR-CP-O2
TOR-CP 105 80 C. oven drying for 5 minutes TOR-CP-O3 TOR-CP 171 80
C. oven drying for 5 minutes TOR-CP-A1 TOR-CP 70 RT air dry for 60
minutes and followed by 80 C. oven drying for 5 minutes TOR-CP-A2
TOR-CP 107 RT air dry for 60 minutes and followed by 80 C. oven
drying for 5 minutes
[0221] FIGS. 9A-D are explained in more detail as follows. In
particular, FIG. 9A shows measured values of electrical resistivity
of the resulting coatings as a function of coating thickness for
Baytron-P and Tor-CP coatings. For Tor-CP coatings two different
drying methods were employed as described in Table 2. Resistivity
of these coatings was measured by employing a standard four point
probe technique and calculated for the known coating thickness and
geometrical correction factor (ASTM Standard F374). Accuracy of the
measured values of resistivity using four point probe method were
confirmed by employing a Van der Pauw technique for the selected
coating at outside laboratory.
[0222] As shown in FIG. 9A for the given coating thickness,
coatings from Tor-CP exhibited at least two orders of lower
resistivity, higher electric conductivity, than that of Baytron-P
coatings. For example, resistivity of the 105 nm thickness Tor-CP
coating was 0.35 ohm-cm, while Resistivity of the 120 nm thickness
Baytron-P coating was 162.74 ohm-cm. Furthermore, air/oven dried
Tor-CP coatings exhibited 2-3 times lower resistivity than that of
oven dried Tor-CP coatings. In air/oven dried Tor-CP coating, we
measured Resistivity as low as 0.15 ohm-cm for coating thickness of
107 nm. There have been reports of lower Resistivity values than
measured in the present example for the Baytron-P conducting
polymer families. However, specific test conditions and coating
process conditions are not clearly reported. Direct comparison
between externally reported values and our measured resistivity
values for Baytron-P are not always accurate. Resistivity values
for the Baytron-P coatings were used as a reference in the present
invention when coatings of Baytron-P and Tor-CP were processed and
measured same way.
[0223] It is significant that the air/oven dried coatings exhibited
lower Resistivity than the oven dried coating, while other measured
properties are appears to be same such as optical
transmission/absorbance and surface morphology. Without wishing to
be bound to theory, it is possible that the method impacts micro
structural properties.
[0224] Coating samples made from Tor-CP or Baytron-P were
intentionally exposed to uncontrolled laboratory conditions without
any protection. About a month after, Resistivity of these samples
was re-measured. While resistivities of the Tor-CP coating were
remained the same (unchanged), Baytron-P coating became too soft.
Without wishing to be bound to any theory, it is possible that the
Baytron-P reacts with moisture in the ambient atmosphere, and
resistivity could not be determined by using the four point probe.
This result clearly indicated that coatings of Tor-CP are
substantially more stable than that of Baytron-P.
[0225] Treatment temperatures of up to about 200 C have been
achieved by oven drying. Substantially better results were not
always seen. See also FIG. 12 providing resistivity and resistance
data for selected TOR-CP and Baytron-P samples.
[0226] EXAMPLE 7
Optical Transmission of TOR-CP and Baytron-P Coatings
[0227] FIG. 10 shows optical transmission of the Tor-CP and
Baytron-P coatings, as a function of coating thickness, determined
by UV-Vis-near IR dual beam differential spectrophotometer (Varian
Model No. 2200). Black glass substrate (no coating on it) was used
as a reference sample for each test, therefore, measured values of
transmission/absorbance were coating layer properties only.
Briefly, samples were scanned between 900 nm and 260 nm ranges with
spectral bandwidth of 1 nm and scan rate of 1 nm/sec. As shown in
FIG. 10, optical transmission/absorbance property is almost same
for the coating of Tor-CP and Baytron-P for the given coating
thickness. For a 105 nm thickness Tor-CP coating, transmission was
above 90% wavelength ranges between 300 nm and 600 nm and it
gradually dropped to 83% at 700 nm. A 120 nm thickness Baytron-P
coating exhibited similar transmission/absorbance characteristics
in the same measurement.
EXAMPLE 8
Preparation and Use of an OLED
[0228] Standard OLED devices, with Tor-CP or Baytron-P as a hole
injection buffer layer, were fabricated and characterized. See
generally Organic Light-Emitting Materials and Devices IV, Kafafi,
Z. H. Editor, in Proceedings of SPIE, vol. 4105 (2001) and
references cited therein for disclosure relating to making and
using standard OLED and related devices.
[0229] The specific device structure used in both cases was: ITO
(150 nm)/Tor-CP or PEDOT:PSS/TPD (20 nm)/Alq.sub.3 (40 nm)/LiF (0.5
nm)/Al (200 nm). As shown in FIG. 11, OLED with Tor-CP reached a
peak external quantum efficiency of 0.18% or a peak power
efficiency of 1.08 lm/W at an applied bias of 5.10 V and a
luminance of 8,790 cd/m.sup.2. The maximum luminance of 32,000
cd/m.sup.2 was obtained at 7.1 V. This compares to a similar water
based PEDOT:PSS sample (heated at 50.degree. C. and dried in
N.sub.2) fabricated at the same time which had a peak external
quantum efficiency of 0.15% or a peak power efficiency of 0.82 lm/W
at an applied bias of 5.40 V and a luminance of 8,620 cd/m.sup.2.
The water based (PEDOT) device had a maximum luminance of 14,700
cd/m.sup.2 obtained at 7.0 V. The superior performance of the
Tor-CP in OLED devices suggests that improved electrical
characteristics (for such applications) has been achieved. See also
FIG. 11.
[0230] As illustrated by this example, the OLED with the TOR-CP
exhibited a better performance than the corresponding OLED with
Baytron-P ITO.
EXAMPLE 9
Use of Tor-CP as an Electrode
[0231] Tor-CP can be used as an anode electrodes for display
applications by replacing current industry standard of indium doped
tin oxides (ITO). An example of this application is shown in FIGS.
13 and 14.
[0232] In FIG. 13, measured surface resistance (in ohm/sq.) of the
Tor-CP coating on 5 mil thickness PET substrate is shown as a
function of number of spin coating layers. Baytron-P from Bayer A.
G. was used as a reference material in this experiment. With two to
three layer spin coatings, Tor-CP exhibited about 1-2 kohm/sq.
surface resistance whereas Baytron-P exhibited about 100 kohm/sq.
Optical transmission for the same set of coatings is above 86% and
below 80% for Tor-CP and Baytron-P, respectively. Generally, for
certain display applications, such as touch screen, anode electrode
(currently ITO) should have surface resistance of less than 1-2
kohm/sq. and optical transmission of above 86%. Clearly, Tor-CP
coatings can meet these requirements.
[0233] In addition, adhesion tests of these samples following
Mil-C-4897A test protocol were also conducted. Results of this test
indicated that Tor-CP exhibited very good adhesion rating of 4B,
compared to very poor adhesion of Baytron-P on PET. Since the
Tor-CP is in NMP, there is a surface mixing effect between Tor-CP
and PET substrate whereas aqueous based Baytron-P may not have the
mixing effect. The mixing effect between the Tor-CP and PET
substrates at the interface would provide good adhesion.
[0234] FIG. 15 shows data in support of FIGS. 13 and 14.
EXAMPLE 10
Properties of Tor-CP and Baytron-P Coatings
[0235] Resistivity/Conductivity of Tor-CP and Baytron-P coatings on
glass substrates were determined by employing van der Pauw method
in temperature ranges between 100-300 K. Thickness of the coatings
used in this test were between 400-500 nm. Ln-Ln plots of the
conductivity results are shown in FIGS. 16 and 17. As shown in
these figures, Tor-CP coatings exhibited two orders higher
conductivity than Baytron-P coatings in entire temperature ranges.
In addition, Baytron-P coatings exhibited a kink at temperatures
around 150 K whereas there is no kink in the plots of Tor-CP
coatings. It is believed that the kink in the Ln-Ln plot of the
conductivity indicated the changes in charge carrier transport
mechanism in the Baytron-P coatings. No kink in the Tor-CP coatings
probably implies solid charge carrier transport mechanism in Tor-CP
coatings and might attribute to the many orders higher mobility in
the Tor-CP coatings.
[0236] All references disclosed in this application are
incorporated herein by reference.
[0237] While the invention has been described with reference to
specific embodiments, modifications and variations of the invention
may be constructed without departing from the scope of the
invention, which is defined in the following claims.
* * * * *