U.S. patent application number 13/767435 was filed with the patent office on 2013-08-15 for planarization layer for organic electronic devices.
This patent application is currently assigned to PROMERUS LLC. The applicant listed for this patent is MERCK PATENT GMBH, PROMERUS LLC. Invention is credited to Irina Afonina, Tomas Backlund, Andrew Bell, Paul Craig Brookes, Pawel Miskiewicz, Larry F. Rhodes, Li Wei Tan, Piotr Wierzchowiec.
Application Number | 20130207091 13/767435 |
Document ID | / |
Family ID | 48944870 |
Filed Date | 2013-08-15 |
United States Patent
Application |
20130207091 |
Kind Code |
A1 |
Wierzchowiec; Piotr ; et
al. |
August 15, 2013 |
PLANARIZATION LAYER FOR ORGANIC ELECTRONIC DEVICES
Abstract
The invention relates to organic electronic devices containing
polycycloolefin planarization layers between the substrate and a
functional layer like a semiconducting layer, dielectric layer or
electrode, to the use of polycycloolefins as planarization layer on
the substrate of an organic electronic device, and to processes for
preparing such polycycloolefin planarization layers and organic
electronic devices.
Inventors: |
Wierzchowiec; Piotr;
(Southampton, GB) ; Miskiewicz; Pawel; (Cambridge,
MA) ; Backlund; Tomas; (Southampton, GB) ;
Tan; Li Wei; (Eastleigh, GB) ; Brookes; Paul
Craig; (Southampton, GB) ; Afonina; Irina;
(Southampton, GB) ; Rhodes; Larry F.; (Silver
Lake, OH) ; Bell; Andrew; (Lakewood, OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MERCK PATENT GMBH;
PROMERUS LLC; |
|
|
US
US |
|
|
Assignee: |
PROMERUS LLC
BRECKSVILLE
OH
MERCK PATENT GMBH
DARMSTADT
|
Family ID: |
48944870 |
Appl. No.: |
13/767435 |
Filed: |
February 14, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61599069 |
Feb 15, 2012 |
|
|
|
Current U.S.
Class: |
257/40 ;
438/99 |
Current CPC
Class: |
Y02P 70/521 20151101;
H01L 51/0541 20130101; H01L 51/0545 20130101; C08F 232/08 20130101;
H01L 51/0001 20130101; H01L 51/0094 20130101; H01L 51/0035
20130101; H01L 51/0096 20130101; Y02E 10/549 20130101; H01L 51/0012
20130101; H01L 51/107 20130101; H01L 51/0034 20130101; C08G
2261/418 20130101; Y02P 70/50 20151101; H01L 51/0508 20130101 |
Class at
Publication: |
257/40 ;
438/99 |
International
Class: |
H01L 51/10 20060101
H01L051/10; H01L 51/00 20060101 H01L051/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 15, 2012 |
EP |
12000974.1 |
Claims
1. An organic electronic device comprising a substrate, and
provided on said substrate a functional layer selected from
semiconducting layers, dielectric layers and electrodes, wherein a
planarization layer is provided between the substrate and the
functional layer, wherein said planarization layer comprises a
polycycloolefinic polymer.
2. The organic electronic device of claim 1, wherein the
polycycloolefinic polymer is a norbornene-type polymer.
3. The organic electronic device of claim 1, wherein the
polycycloolefinic polymer comprises two or more distinct types of
repeating units.
4. The organic electronic device of claim 1, wherein the
polycycloolefinic polymer comprises a first type of repeating unit
having a pendant crosslinkable group.
5. The organic electronic device of claim 4, wherein the pendant
crosslinkable group is a latent crosslinkable group.
6. The organic electronic device of claim 5, wherein the pendant
crosslinkable group comprises a substituted or unsubstituted
maleimide portion, an epoxide portion, a vinyl portion, an
acetylene portion, an indenyl portion, a cinnamate portion or a
coumarin portion.
7. The organic electronic device of claim 6, wherein the first type
of repeating unit having a pendant crosslinkable group is derived
during polymerization from one of the following monomers:
##STR00017## where n is an integer from 1 to 8, Q.sup.1 and Q.sup.2
are each independently selected from --H or --CH.sub.3, and R' in
P4 is --H or --OCH.sub.3.
8. The organic electronic device of claim 4, wherein the
polycycloolefinic polymer comprises a second type of repeating
units having a pendant silyl group.
9. The organic electronic device of claim 1, wherein the
polycycloolefinic polymer comprises one or more distinct types of
repeating units represented by formula I ##STR00018## wherein Z is
selected from --CH.sub.2--, --CH.sub.2--CH.sub.2-- or --O--, m is
an integer from 0 to 5, each of R.sup.1, R.sup.2, R.sup.3 and
R.sup.4 are independently selected from H, a C.sub.1 to C.sub.25
hydrocarbyl, a C.sub.1 to C.sub.25 halohydrocarbyl or a C.sub.1 to
C.sub.25 perhalocarbyl group.
10. The organic electronic device of claim 9, wherein the
polycycloolefinic polymer comprises one or more distinct types of
repeating units formed from norbornene-type monomers independently
selected from the following formulae: ##STR00019## wherein b is an
integer from 1 to 6.
11. The organic electronic device of claim 9, wherein the
polycycloolefinic polymer comprises one or more distinct types of
repeating units formed from norbornene-type monomers independently
selected from the following formulae: ##STR00020##
12. The organic electronic device of claim 9, wherein the
polycycloolefinic polymer comprises one or more distinct types of
repeating units formed from norbornene-type monomers independently
selected from the following formulae: ##STR00021##
13. The organic electronic device of claim 1, wherein the
planarization layer comprises two or more polycycloolefinic
polymers having one or more distinct types of repeating units of
formula I ##STR00022## wherein Z is selected from --CH.sub.2--,
--CH.sub.2--CH.sub.2-- or --O--, m is an integer from 0 to 5, each
of R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are independently selected
from H, a C.sub.1 to C.sub.25 hydrocarbyl, a C.sub.1 to C.sub.25
halohydrocarbyl or a C.sub.1 to C.sub.25 perhalocarbyl group.
14. The organic electronic device of claim 1, wherein the
planarization layer is derived from a polymer composition
comprising one or more of a solvent, a crosslinking agent, an
optional reactive solvent, a stabilizer, a UV sensitizer, an
adhesion promoter, and a thermal sensitizer.
15. The organic electronic device of claim 14, wherein the polymer
composition comprises a compound selected of formula III1 or III2
P-A''-X'-A''-P III1 H.sub.4-cC(A''-P).sub.c III2 wherein X' is O,
S, NH or a single bond, A'' is a single bond or a connecting,
spacer or bridging group selected from (CZ.sub.2).sub.n,
(CH.sub.2).sub.n--(CH.dbd.CH).sub.p--(CH.sub.2).sub.n,
(CH.sub.2).sub.n--O--(CH.sub.2).sub.n,
(CH.sub.2).sub.n--C.sub.6Q.sub.10-(CH.sub.2).sub.n, and C(O), where
each n is independently an integer from 0 to 12, p is an integer
from 1-6, Z is independently H or F, C.sub.6Q.sub.10 is cyclohexyl
that is substituted with Q, Q is independently H, F, CH.sub.3,
CF.sub.3 or OCH.sub.3, P is a latent crosslinkable group, and c is
2, 3 or 4, and where in formula III1 at least one of X' and the two
groups A'' is not a single bond.
16. The organic electronic device of claim 15, wherein the compound
of formula III1 is selected of formula C1: ##STR00023## wherein
R.sup.10 and R.sup.11 are independently of each other H or a
C.sub.1-C.sub.6 alkyl group and A'' is as defined in claim 15.
17. The organic electronic device of claim 14, wherein the polymer
composition comprises a compound of formula IV G-A''-P IV wherein G
is a surface-active group of the formula
--SiR.sup.12R.sup.13R.sup.14, or a group of the formula
--NH--SiR.sup.12R.sup.13R.sup.14, wherein R.sup.12, R.sup.13 and
R.sup.14 are each independently selected from halogen, silazane,
C.sub.1-C.sub.12-alkoxy, C.sub.1-C.sub.12-alkylamino, optionally
substituted C.sub.5-C.sub.20-aryloxy and optionally substituted
C.sub.2-C.sub.20-heteroaryloxy, and wherein one or two of R.sup.12,
R.sup.13 and R.sup.14 may also denote C.sub.1-C.sub.12-alkyl,
optionally substituted C.sub.5-C.sub.20-aryl or optionally
substituted C.sub.2-C.sub.20-heteroaryl, P is a crosslinkable group
selected from a maleimide, a 3-monoalkyl-maleimide, a
3,4-dialkylmaleimide, an epoxy, a vinyl, an acetylene, an indenyl,
a cinnamate or a coumarin group, or comprises a substituted or
unsubstituted maleimide portion, an epoxide portion, a vinyl
portion, an acetylene portion, an indenyl portion, a cinnamate
portion or a coumarin portion, and A'' is a single bond or a
connecting, spacer or bridging group selected from
(CZ.sub.2).sub.n,
(CH.sub.2).sub.n--(CH.dbd.CH).sub.p--(CH.sub.2).sub.n,
(CH.sub.2).sub.n--O, (CH.sub.2).sub.n--O--(CH.sub.2).sub.n,
(CH.sub.2).sub.n--C.sub.6Q.sub.4-(CH.sub.2).sub.n,
(CH.sub.2).sub.n--C.sub.6Q.sub.10-(CH.sub.2).sub.n and C(O)--O,
where each n is independently an integer from 0 to 12, p is an
integer from 1-6, Z is independently H or F, C.sub.6Q.sub.4 is
phenyl that is substituted with Q, C.sub.6Q.sub.10 is cyclohexyl
that is substituted with Q, Q is independently H, F, CH.sub.3,
CF.sub.3 or OCH.sub.3.
18. The organic electronic device of claim 17, wherein the compound
of formula IV is selected of formula A1: ##STR00024## where
R.sup.12, R.sup.13 R.sup.14, and A'' are as defined in claim 17,
and R.sup.10 and R.sup.11 are each independently H or a
C.sub.1-C.sub.6 alkyl group.
19. The organic electronic device of claim 1, wherein the substrate
is a polyester film.
20. The organic electronic device of claim 19, wherein the
substrate is a polyethyleneterephthalate (PET) or
polyethylenenaphthalate (PEN) film.
21. The organic electronic device of claim 1, wherein an electrode
is formed on the planarization layer.
22. The organic electronic device of claim 1, wherein an organic
semiconductor layer is formed on the planarization layer.
23. The organic electronic device of claim 1, wherein a dielectric
layer is formed on the planarization layer.
24. The organic electronic device of claim 1, which is an Organic
Field Effect Transistor (OFET), Organic Photovoltaic (OPV) Device,
or Organic Sensor.
25. The organic electronic device of claim 24, which is a top gate
OFET or a bottom gate OFET.
26. A product or assembly comprising an organic electronic device
of claim 1, which is an Integrated Circuit (IC), a Radio Frequency
Identification (RFID) tag, a security marking or security device
containing an RFID tag, a Flat Panel Display (FPD), a backplane of
an FPD, or a sensor.
27. A process for preparing the top gate OFET of claim 25,
comprising: a) depositing a layer of planarization material, which
comprises a polycycloolefinic polymer or a polymer composition on a
substrate, b) forming source and drain electrodes on at least a
portion of planarization layer, c) depositing a layer of organic
semiconductor material over said planarization layer and source and
drain electrodes, d) depositing a layer of dielectric material on
organic semiconductor layer, e) forming gate electrode on at least
a portion of dielectric layer and f) optionally depositing layer,
which is an insulating and/or protection and/or stabilizing and/or
adhesive layer, on the gate electrode and portions of dielectric
layer.
28. A process for preparing the bottom gate OFET of claim 25,
comprising: a) depositing a layer of planarization material, which
comprises a polycycloolefinic polymer or a polymer composition on a
substrate, b) forming gate electrode on at least a portion of
planarization layer as depicted, c) depositing a layer of
dielectric material over said planarization layer and gate
electrode, d) depositing a layer of organic semiconductor material)
on dielectric layer, e) forming source and drain electrodes on at
least a portion of organic semiconductor layer as depicted, and f)
optionally depositing layer, which is an insulating and/or
protection and/or stabilizing and/or adhesive layer, on the source
and drain electrodes and portions of organic semiconductor layer.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit to U.S. Provisional
Application No. 61/599,069 filed Feb. 15, 2012 and EP Application
No. 12000974.1 filed on Feb. 15, 2012 which both are incorporated
by reference in its entirety.
TECHNICAL FIELD
[0002] Embodiments in accordance with the present invention relate
to organic electronic devices comprising polycycloolefin
planarization layers, and more particularly to planarization layers
positioned between the substrate and a functional layer, e.g. a
semiconducting layer, a dielectric layer or an electrode, and
further to the use of such a planarization layer in organic
electronic devices, and to processes for preparing such
polycycloolefin planarization layers and organic electronic
devices.
BACKGROUND
[0003] In recent years there has been growing interest in organic
electronic (OE) devices, for example field effect transistors for
use in display devices and logic capable circuits, or organic
photovoltaic (OPV) devices. A conventional organic field effect
transistor (OFET) typically includes source, drain and gate
electrodes, a semiconducting layer made of an organic semiconductor
(OSC) material, and an insulator layer (also referred to as
"dielectric" or "gate dielectric"), made of a dielectric material
and positioned between the OSC layer and the gate electrode.
[0004] A broad range of different substrates can be used for OE
devices like OFETs and OPVs. The most common are polymers like
polyethylene terephthalate (PET), polyethylene naphthalate (PEN),
other polyesters, polyimide, polyacrylate, polycarbonate,
polyvinylalcohol, polycycloolefin or polyethersulphone. Thin metal
films, paper based substrates, glass and others are also
available.
[0005] However, the substrates that have hitherto been available
often contain defects and contamination from the production
process. Therefore, for the purpose of integrity of the thin-film
OE devices made on top of them, most of these substrates require an
additional planarization or barrier layer in order to provide a
smooth and defect-free surface.
[0006] Further reasons or functions requiring the application of an
intermediate layer between substrate and OSC material include: 1)
improving the hardness/scratch resistance of the substrate, 2)
providing electrical isolation of the substrate and the OSC layer,
3) providing a barrier to prevent diffusion of metal ions, small
molecules, and oligomers from the carrier substrate to OSC, 4)
modifying wetting properties of the substrate, and 5) acting as
adhesion promoter.
[0007] Various plastic film substrates are commercially available,
like for example PET films of the Melinex.RTM. series or PEN films
of the Teonex.RTM. series, both from DuPont Teijin Films.TM.
[0008] Typical commercially available planarization, hard-coating,
or barrier materials include:
[0009] 1) Silicon dioxide (SiO.sub.2) or silicon nitride (SiNX)
electrical insulators, which are used mainly on top of conducting
metal substrates.
[0010] 2) Organic polymers, such as, acrylic-, melamine- or
urethane-based polymers.
[0011] 3) Organic-inorganic hybrid composites, which are based
mainly on the use of metal alkoxide and organosiloxane via sol-gel
processing, as disclosed for example in U.S. Pat. No. 5,976,703 or
in W. Tanglumlert et al. `Hard-coating materials for poly(methyl
methacrylate) from glycidoxypropyl-trimethoxysilane-modified
silatrane via sol-gel process`, Surface & Coatings Technology
200 (2006) p. 2784.
[0012] Nevertheless, to date there has been no planarization
material which fulfils all requirements for all the commercially
available OE/OPV materials. Two of the major weaknesses of the
currently available materials are: 1) a low surface energy, which
causes de-wetting of OSC materials during coating, therefore
requiring additional pre-treatment, and 2) a high permeation of the
available polymers and composites to water. Therefore, the
above-mentioned materials are not suitable for many OE/OPV
applications unless an additional barrier or surface modification
layer is applied.
[0013] Moreover, the inventors have found that the planarization
materials used in commercially available PET or PEN substrates have
turned out not to be fully compatible with recently developed high
performance OSC materials, like those of the Lisicon.RTM. Series
(commercially available from Merck KGaA or Merck Chemicals Ltd.).
Further, poor electrical stability of devices using the
Lisicon.RTM. Series OSC directly on top of planarised Melinex.RTM.
and Teonex.RTM. has been observed. Therefore, an additional
barrier/surface modification layer on top of the existing
planarization layer, or a replacement for the planarization layer
would be advantageous.
[0014] In general, a planarization material should exhibit one or
more of the following characteristics:
[0015] 1). acting as an electrical insulator,
[0016] 2). providing a smooth surface (preferably arithmetic
average roughness of absolute values (Ra)<5 and maximum high of
the profile (Rt)<50),
[0017] 3). providing for the electrical performance and stability
of OTFTs compared to the best working example on any other
substrate,
[0018] 4). enabling good adhesion between the substrate and
electrode metals (preferably 5N/cm or higher),
[0019] 5). possessing good wetting properties for OSC formulations
(preferably a surface energy of the planarization layer.gtoreq.50
mN/m),
[0020] 6). inherent resistance to process chemicals,
[0021] 7). optical transparency in the visible spectrum,
[0022] 8). deposition using well established industrial
processes.
[0023] Therefore, there is still a need for improved planarization
layers which can be used in OE devices, especially OFETs and OPV
cells, which fulfil the above-mentioned requirements.
[0024] One aim of the present invention is to provide planarization
layers meeting these requirements. Another aim is to provide
improved OE/OPV devices comprising such planarization layers.
Further aims are immediately evident to the person skilled in the
art from the following description.
[0025] The inventors of the present invention have found these aims
can be achieved by providing planarization layers and OE devices in
accordance with the present invention and as claimed
hereinafter.
SUMMARY OF THE INVENTION
[0026] Embodiments in accordance with the present invention
encompass an organic electronic device overlying a substrate, the
substrate having a planarization layer provided between the
substrate and a functional layer, where the planarization layer
encompasses a polycycloolefinic polymer and the functional layer is
one of a semiconducting layer, a dielectric layer or an
electrode.
[0027] Some embodiments in accordance with the present invention
are also directed to the use of the aforementioned planarization
layer in an organic electronic device. Still further, some
embodiments are directed to a method of using a polycycloolefinic
polymer in the fabrication of a planarization layer for an organic
electronic device.
[0028] The aforementioned polycycloolefinic polymer is for example
a norbornene-type polymer.
[0029] The aforementioned organic electronic device is for example
an Organic Field Effect Transistor (OFET), which is inclusive of an
Organic Thin Film Transistor (OTFT), a top gate OFET, a bottom gate
OFET, an Organic Photovoltaic (OPV) Device or an Organic
Sensor.
[0030] Embodiments of the present invention are also inclusive of a
product or an assembly encompassing an organic electronic device as
described above and below. Such product or assembly being an
Integrated Circuit (IC), a Radio Frequency Identification (RFID)
tag, a security marking or security device containing an RFID tag,
a Flat Panel Display (FPD), a backplane of an FPD, or a sensor.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] Embodiments in accordance with the present invention are
described below with reference to the following drawings.
[0032] FIG. 1 is a schematic representation of a top gate OFET
device according to prior art;
[0033] FIG. 2 is a schematic representation of a bottom gate OFET
device according to prior art;
[0034] FIG. 3 is a schematic representation of a top gate OFET
device in accordance with an embodiment of the present
invention;
[0035] FIG. 4 is a schematic representation of a bottom gate OFET
device in accordance with an embodiment of the present
invention;
[0036] FIG. 5 is a transfer curve of the top gate OFET device of
Comparison Example 1;
[0037] FIG. 6 is a transfer curve of the top gate OFET device of
Example 1;
[0038] FIG. 7 is a transfer curve of the top gate OFET device of
Comparison Example 2;
[0039] FIG. 8 is a transfer curve of the top gate OFET device of
Example 2; and
[0040] FIG. 9 is a transfer curve of the top gate OFET device of
Example 3.
DETAILED DESCRIPTION OF THE INVENTION
[0041] Exemplary embodiments in accordance with the present
invention will be described with reference to the Examples and
Claims provided hereinafter. Various modifications, adaptations or
variations of such exemplary embodiments described herein may
become apparent to those skilled in the art as such are disclosed.
It will be understood that all such modifications, adaptations or
variations that rely upon the teachings of the present invention,
and through which these teachings have advanced the art, are
considered to be within the scope of the present invention.
[0042] As used herein, the articles "a," "an," and "the" include
plural referents unless otherwise expressly and unequivocally
limited to one referent.
[0043] Since all numbers, values and/or expressions referring to
quantities of ingredients, reaction conditions, etc., used herein
and in the Exhibits and Claims appended hereto, are subject to the
various uncertainties of measurement encountered in obtaining such
values, unless otherwise indicated, all are to be understood as
modified in all instances by the term "about."
[0044] Where a numerical range is disclosed herein, unless
otherwise specified, such range is continuous, inclusive of both
the minimum and maximum values of the range as well as every value
between such minimum and maximum values. Still further, where a
range refers to integers, every integer between the minimum and
maximum values of such range is included. In addition, where
multiple ranges are provided to describe a feature or
characteristic, such ranges can be combined. That is to say that,
unless otherwise indicated, all ranges disclosed herein are to be
understood to encompass any and all subranges subsumed therein. For
example, a stated range of from "1 to 10" should be considered to
include any and all subranges between the minimum value of 1 and
the maximum value of 10. Exemplary subranges of the range 1 to 10
include, but are not limited to, 1 to 6.1, 3.5 to 7.8, and 5.5 to
10.
[0045] Advantageously, the polycycloolefinic or norbornene-type
polymers used in the planarization layers of the present invention
are tailorable to overcome the drawbacks that have been observed in
previously known planarization materials, such as poor electrical
stability of the OSC in contact with the planarization layer, low
surface energy which causes de-wetting of the OSC material during
coating.
[0046] Moreover, the planarization layers comprising
polycycloolefinic polymers show improved adhesion to the substrate
and to electrodes, reduced surface roughness, and improved OSC
performance.
[0047] The planarization layers comprising polycycloolefinic
polymers allow for time-, cost- and material-effective production
of OFETs employing organic semiconductor materials and organic
dielectric materials on a large scale.
[0048] Further, as will be discussed, the polycycloolefinic or
norbornene-type polymers can, in combination with the substrate
and/or with functional layers like the organic dielectric layer or
the OSC layer, provide improved surface energy, adhesion and
structural integrity of such combined layers in comparison with
planarization materials of prior art that have been employed in
such OFETs.
[0049] As used herein, the term "polymer" will be understood to
mean a molecule that encompasses a backbone of one or more distinct
types of repeating units (the smallest constitutional unit of the
molecule) and is inclusive of the commonly known terms "oligomer",
"copolymer", "homopolymer" and the like. Further, it will be
understood that the term polymer is inclusive of, in addition to
the polymer itself, residues from initiators, catalysts and other
elements attendant to the synthesis of such a polymer, where such
residues are understood as not being covalently incorporated
thereto. Further, such residues and other elements, while normally
removed during post polymerization purification processes, are
typically mixed or co-mingled with the polymer such that they
generally remain with the polymer when it is transferred between
vessels or between solvents or dispersion media.
[0050] As used herein, the terms "orthogonal" and "orthogonality"
will be understood to mean chemical orthogonality. For example, an
orthogonal solvent means a solvent which, when used in the
deposition of a layer of a material dissolved therein on a
previously deposited layer, does not dissolve said previously
deposited layer.
[0051] As used herein, the term "polymer composition" means at
least one polymer and one or more other materials added to the at
least one polymer to provide, or to modify, specific properties of
the polymer composition and or the at least one polymer therein. It
will be understood that a polymer composition is a vehicle for
carrying the polymer to a substrate to enable the forming of layers
or structures thereon. Exemplary materials include, but are not
limited to, solvents, antioxidants, photoinitiators,
photosensitizers, crosslinking moieties or agents, reactive
diluents, acid scavengers, leveling agents and adhesion promoters.
Further, it will be understood that a polymer composition may, in
addition to the aforementioned exemplary materials, also encompass
a blend of two or more polymers.
[0052] As defined herein, the terms "polycycloolefin", "polycyclic
olefin", and "norbornene-type" are used interchangeably and refer
to addition polymerizable monomers, or the resulting repeating
unit, encompassing at least one norbornene moiety such as shown by
either Structure A1 or A2, below. The simplest norbornene-type or
polycyclic olefin monomer bicyclo[2.2.1]hept-2-ene (A1) is commonly
referred to as norbornene.
##STR00001##
[0053] However, the term "norbornene-type monomer" or
"norbornene-type repeating unit", as used herein, is understood to
not only mean norbornene itself but also to refer to any
substituted norbornene, or substituted and unsubstituted higher
cyclic derivatives thereof, for example of Structures B1 and B2,
shown below, wherein m is an integer greater than zero.
##STR00002##
[0054] By the substitution of a norbornene-type monomer with a
pendant group, the properties of a polymer formed therefrom can be
tailored to fulfill the needs of individual applications. The
procedures and methods that have been developed to polymerize
functionalized norbornene-type monomers exhibit an outstanding
flexibility and tolerance to various moieties and groups of the
monomers. In addition to polymerization of monomers with a specific
pendant group, monomers having a variety of distinct
functionalities can be randomly polymerized to form a final
material where the types and ratios of monomers used dictate the
overall bulk properties of the resulting polymer.
[0055] As used herein, "hydrocarbyl" refers to a radical or group
that contains a carbon backbone where each carbon is appropriately
substituted with one or more hydrogen atoms. The term
"halohydrocarbyl" refers to a hydrocarbyl group where one or more
of the hydrogen atoms, but not all, have been replaced by a halogen
(F, Cl, Br, or I). The term perhalocarbyl refers to a hydrocarbyl
group where each hydrogen has been replaced by a halogen.
Non-limiting examples of hydrocarbyls, include, but are not limited
to a C.sub.1-C.sub.25 alkyl, a C.sub.2-C.sub.24 alkenyl, a
C.sub.2-C.sub.24 alkynyl, a C.sub.5-C.sub.25 cycloalkyl, a
C.sub.6-C.sub.24 aryl or a C.sub.7-C.sub.24 aralkyl. Representative
alkyl groups include but are not limited to methyl, ethyl, propyl,
isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl,
neopentyl, hexyl, heptyl, octyl, nonyl, decyl and dodecyl.
Representative alkenyl groups include but are not limited to vinyl,
propenyl, butenyl and hexenyl. Representative alkynyl groups
include but are not limited to ethynyl, 1-propynyl, 2-propynyl, 1
butynyl, and 2-butynyl. Representative cycloalkyl groups include
but are not limited to cyclopentyl, cyclohexyl, and cyclooctyl
substituents. Representative aryl groups include but are not
limited to phenyl, biphenyl, naphthyl, and anthracenyl.
Representative aralkyl groups include but are not limited to
benzyl, phenethyl and phenbutyl.
[0056] The term "halohydrocarbyl" as used herein is inclusive of
the hydrocarbyl moieties mentioned above but where there is a
degree of halogenation that can range from at least one hydrogen
atom being replaced by a halogen atom (e.g., a fluoromethyl group)
to where all hydrogen atoms on the hydrocarbyl group have been
replaced by a halogen atom (e.g., trifluoromethyl or
perfluoromethyl), also referred to as perhalogenation. The term
"perhalohydrocarbyl"=as used herein is inclusive of the hydrocarbyl
moieties mentioned above but where all the hydrogen atom being
replaced by a halogen atom. For example, halogenated alkyl groups
that can be useful in embodiments of the present invention can be
partially or fully halogenated, alkyl groups of the formula
C.sub.aX.sub.2a+1 wherein X is independently a halogen or a
hydrogen and a is selected from an integer of 1 to 25. In some
embodiments each X is independently selected from hydrogen,
chlorine, fluorine bromine and/or iodine. In other embodiments each
X is independently either hydrogen or fluorine. Thus,
representative halohydrocarbyls and perhalocarbyls are exemplified
by the aforementioned exemplary hydrocarbyls where an appropriate
number of hydrogen atoms are each replaced with a halogen atom.
[0057] In addition, the definition of the terms "hydrocarbyl",
"halohydrocarbyl", and "perhalohydrocarbyl", are inclusive of
moieties where one or more of the carbons atoms is replaced by a
heteroatom selected independently from O, N, P, or Si. Such
heteroatom containing moieties can be referred to as, for example,
either "heteroatom-hydrocarbyls" or "heterohydrocarbyls",
including, among others, ethers, epoxies, glycidyl ethers,
alcohols, carboxylic acids, esters, maleimides, amines, imines,
amides, phenols, amido-phenols, silanes, siloxanes, phosphines,
phosphine oxides, phosphinites, phosphonites, phosphites,
phosphonates, phosphinates, and phosphates.
[0058] Further exemplary hydrocarbyls, halohydrocarbyls, and
perhalocarbyls, inclusive of heteroatoms, include, but are not
limited to,
--(CH.sub.2).sub.n--Ar--(CH.sub.2).sub.n--C(CF.sub.3).sub.2--OH,
--(CH.sub.2).sub.n--Ar--(CH.sub.2).sub.n--OCH.sub.2C(CF.sub.3).sub.2--OH,
--(CH.sub.2).sub.n--C(CF.sub.3).sub.2--OH,
--((CH.sub.2).sub.1--O--).sub.k--(CH.sub.2)--C(CF.sub.3).sub.2--OH,
--(CH.sub.2).sub.n--C(CF.sub.3)(CH.sub.3)--OH,
--(CH.sub.2).sub.n--C(O)NHR*, --(CH.sub.2).sub.n--C(O)Cl,
--(CH.sub.2).sub.n--C(O)OR*, --(CH.sub.2).sub.n--OR*,
--(CH.sub.2).sub.n--OC(O)R* and --(CH.sub.2).sub.n--C(O)R*, where n
independently represents an integer from 0 to 12, i is 2, 3 or 4, k
is 1, 2 or 3, Ar is aryl, for example phenyl, and R* independently
represents hydrogen, a C.sub.1-C.sub.11 alkyl, a C.sub.1-C.sub.11
halogenated or perhalogenated alkyl, a C.sub.2-C.sub.10 alkenyl, a
C.sub.2-C.sub.10 alkynyl, a C.sub.5-C.sub.12 cycloalkyl, a
C.sub.6-C.sub.14 aryl, a C.sub.6-C.sub.14 halogenated or
perhalogenated aryl, a C.sub.7-C.sub.14 aralkyl or a halogenated or
perhalogenated C.sub.7-C.sub.14 aralkyl.
[0059] Exemplary perhalogenated alkyl groups include, but are not
limited to, trifluoromethyl, trichloromethyl, --C.sub.2F.sub.5,
--C.sub.3F.sub.7, --C.sub.4F.sub.9, --C.sub.6F.sub.13,
--C.sub.7F.sub.15, and --C.sub.11F.sub.23. Exemplary halogenated or
perhalogenated aryl and aralkyl groups include, but are not limited
to, groups having the formula
--(CH.sub.2).sub.x--C.sub.6F.sub.yH.sub.5-y, and
--(CH.sub.2).sub.x--C.sub.6F.sub.yH.sub.4-y-pC.sub.zF.sub.qH.sub.2z+1-q,
where x, y, q and z are independently selected integers from 0 to
5, 0 to 5, 0 to 9 and 1 to 4, respectively. Specifically, such
exemplary halogenated or perhalogenated aryl groups include, but
are not limited to, pentachlorophenyl, pentafluorophenyl,
pentafluorobenzyl, 4-trifluoromethylbenzyl, pentafluorophenethyl,
pentafluorophenpropyl, and pentafluorophenbutyl.
[0060] In some polymer embodiments in accordance with the
invention, the norbornene-type polymer incorporates two or more
distinct types of repeating units.
[0061] In other polymer embodiments in accordance with the
invention, the norbornene-type polymer incorporates one or more
distinct types of repeating units, where at least one such type of
repeating unit encompasses pendant crosslinkable groups or moieties
that have some degree of latency. By "latency", it is meant that
such groups do not crosslink at ambient conditions or during the
initial forming of the polymers, but rather crosslink when such
reactions are specifically initiated, for example by actinic
radiation or heat. Such latent crosslinkable groups are
incorporated into the polymer backbone by, for example, providing
one or more norbornene-type monomers encompassing such a pendant
crosslinkable group, for example, a substituted or unsubstituted
maleimide or maleimide containing pendant group, to the
polymerization reaction mixture and causing the polymerization
thereof. Other examples of crosslinkable groups encompass a group
comprising a substituted or unsubstituted maleimide portion, an
epoxide portion, a vinyl portion, an acetylene portion, an indenyl
portion, a cinnamate portion or a coumarin portion, and more
specifically a group selected from a 3-monoalkyl- or
3,4-dialkylmaleimide, epoxy, vinyl, acetylene, cinnamate, indenyl
or coumarin group.
[0062] Other polymer embodiments in accordance with the invention
contain one or more norbornene-type polymers having one or more
distinct types of repeating units of formula I
##STR00003##
[0063] wherein Z is selected from --CH.sub.2--,
--CH.sub.2--CH.sub.2-- or --O--, m is an integer from 0 to 5, each
of R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are independently selected
from H, a C.sub.1 to C.sub.25 hydrocarbyl, a C.sub.1 to C.sub.25
halohydrocarbyl or a C.sub.1 to C.sub.25 perhalocarbyl group.
[0064] The repeating units of Formula I are formed from the
corresponding norbornene-type monomers of Formula Ia where Z, m and
R.sup.1-R.sup.4 are as defined above:
##STR00004##
[0065] For some polymer embodiments in accordance with the present
invention, for the repeating units and monomers of Formula I and
Ia, Z is --CH.sub.2-- and m is 0, 1 or 2. For other such polymer
embodiments Z is --CH.sub.2-- and m is 0 or 1, and for still other
embodiments, Z is --CH.sub.2-- and m is 0.
[0066] Some embodiments of the invention encompass an organic
electronic device overlying a substrate, the substrate having a
planarization layer provided between the substrate and a functional
layer, where the planarization layer encompasses a polymer
composition that comprises a polycycloolefinic polymer, and the
functional layer is one of a semiconducting layer, a dielectric
layer or an electrode.
[0067] Polymer composition embodiments in accordance with the
invention encompass either a single norbornene-type polymer or a
blend of two or more different norbornene-type polymers. Where such
polymer composition embodiments encompass a single norbornene-type
polymer, such polymer can be a homopolymer, that is to say a
polymer encompassing only one type of repeating unit, or a
copolymer, that is to say a polymer encompassing two or more
distinct types of repeating units. Where such polymer composition
embodiments encompass a blend of different polymers, "different" is
understood to mean that each of the blended polymers encompasses at
least one type of repeating unit, or combination of repeating
units, that is distinct from any of the other blended polymers.
[0068] Other polymer composition embodiments of the invention
encompass a blend of two or more different norbornene-type
polymers, wherein each polymer comprises one or more distinct types
of repeating units of formula I
##STR00005##
[0069] wherein Z is selected from --CH.sub.2--,
--CH.sub.2--CH.sub.2-- or --O--, m is an integer from 0 to 5, each
of R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are independently selected
from H, a C.sub.1 to C.sub.25 hydrocarbyl, a C.sub.1 to C.sub.25
halohydrocarbyl or a C.sub.1 to C.sub.25 perhalocarbyl group.
[0070] The polymer and polymer composition embodiments of the
present invention can advantageously be tailored to provide a
distinct set of properties for each of many specific applications.
That is to say that different combinations of norbornene-type
monomers with several different types of pendant groups can be
polymerized to provide norbornene-type polymers having properties
that provide for obtaining control over properties such as
flexibility, adhesion, dielectric constant, and solubility in
organic solvents, among others. For example, varying the length of
an alkyl pendant group can allow control of the polymer's modulus
and glass transition temperature (Tg). Also, pendant groups
selected from maleimide, cinnamate, coumarin, anhydride, alcohol,
ester, and epoxy functional groups can be used to promote
crosslinking and to modify solubility characteristics. Polar
functional groups, epoxy and triethoxysilyl groups can be used to
provide adhesion to metals, silicon, and oxides in adjacent device
layers. Fluorinated groups, for example, can be used to effectively
modify surface energy, dielectric constant and influence the
orthogonality of the solution with respect to other materials.
[0071] Thus, in further embodiments of the present invention, in
particular for such embodiments where only one of R.sup.1-4 is
different from H, one or more of R.sup.1-4 denote a halogenated or
perhalogenated aryl or aralkyl group including, but not limited to
those of the formula --(CH.sub.2).sub.x--C.sub.6F.sub.yH.sub.5-y,
and
--(CH.sub.2).sub.x--C.sub.6F.sub.yH.sub.4-y-pC.sub.zF.sub.qH.sub.2z+1-q,
where x, y, q, and z are independently selected integers from 0 to
5, 0 to 5, 0 to 9, and 1 to 4, respectively, and "p" means "para".
Specifically such formulae include, but are not limited to,
trifluoromethyl, trichloromethyl, --C.sub.2F.sub.5,
--C.sub.3F.sub.7, --C.sub.4F.sub.9, C.sub.6F.sub.13,
--C.sub.7F.sub.15, --C.sub.11F.sub.23, pentachlorophenyl,
pentafluorophenyl, pentafluorobenzyl, 4-trifluoromethylbenzyl,
pentafluorophenylethyl, pentafluorophenpropyl, and
pentafluorophenbutyl.
[0072] Further still, some embodiments of the present invention, in
particular for such embodiments where only one of R.sup.1-4 is
different from H, encompass a group that is different from H that
is a polar group having a terminal hydroxy, carboxy or
oligoethyleneoxy moiety, for example a terminal hydroxyalkyl,
alkylcarbonyloxy (for example, acetyl), hydroxy-oligoethyleneoxy,
alkyloxy-oligoethyleneoxy or alkylcarbonyloxy-oligoethyleneoxy
moiety, where "oligoethyleneoxy" is understood to mean
--(CH.sub.2CH.sub.2O).sub.s-- with s being 1, 2 or 3; for example
1-(bicyclo[2.2.1]hept-5-en-2-yl)-2,5,8,11-tetraoxadodecane (NBTODD)
where s is 3 and
5-((2-(2-methoxyethoxy)ethoxy)methyl)bicyclo[2.2.1]hept-2-ene
(NBTON) where s is 2.
[0073] Further still, other embodiments of the present invention,
in particular for such embodiments where only one of R.sup.1-4 is
different from H, encompass a group that is different from H that
is a group having a pendant silyl group, for example a silyl group
represented by --(CH.sub.2).sub.n--SiR.sup.9.sub.3 where n is an
integer from 0 to 12, and each R.sup.9 independently represents
halogen selected from the group consisting of chlorine, fluorine,
bromine and iodine, linear or branched (C.sub.1 to C.sub.20)alkyl,
linear or branched (C.sub.1 to C.sub.20)alkoxy, substituted or
unsubstituted (C.sub.6 to C.sub.20)aryl, linear or branched
(C.sub.1 to C.sub.20)alkyl carbonyloxy, substituted or
unsubstituted (C.sub.6 to C.sub.20)aryloxy; linear or branched
(C.sub.1 to C.sub.20) dialkylamido; substituted or unsubstituted
(C.sub.6-C.sub.20) diarylamido; substituted or unsubstituted
(C.sub.1-C.sub.20)alkylarylamido.
[0074] Yet further still, for such embodiments where only one of
R.sup.1-4 is different from H, some embodiments encompass a group
that is either a photoreactive or a crosslinkable group.
Photoreactive or crosslinkable groups encompass a linking portion L
and a functional portion Fp. L denotes or comprises a group
selected from C.sub.1-C.sub.12 alkyls, aralkyls, aryls or hetero
atom analogs. Further Fp denotes or comprises one or more of a
maleimide, a 3-monoalkyl- or 3,4-dialkylmaleimide, epoxy, vinyl,
acetyl, cinnamate, indenyl or coumarin moiety, which is capable of
a crosslinking or 2+2 crosslinking reaction.
[0075] As used herein, the phrase "photoreactive and/or
crosslinkable", when used to describe certain pendant groups, will
be understood to mean a group that is reactive to actinic radiation
and as a result of that reactivity enters into a crosslinking
reaction, or a group that is not reactive to actinic radiation but
can, in the presence of a crosslinking activator, enter into a
crosslinking reaction.
[0076] Exemplary repeating units that encompass a pendant
photoreactive or crosslinkable group that are representative of
Formula I are formed during polymerization from norbornene-type
monomers that include, but are not limited to, those selected from
the following formulae:
##STR00006##
[0077] where n is an integer from 1 to 8, Q.sup.1 and Q.sup.2 are
each independently from one another --H or --CH.sub.3, and R' is
--H or --OCH.sub.3.
[0078] Further exemplary repeating units of Formula I such as
described above are derived from one or more norbornene-type
monomers represented by the following structural formulae 1 through
5 below:
##STR00007##
[0079] For structural formulae I-5 above, m is an integer from 0 to
3, A is a connecting, spacer or bridging group selected from
(CZ.sub.2).sub.n,
(CH.sub.2).sub.n--(CH.dbd.CH).sub.p--(CH.sub.2).sub.n,
(CH.sub.2).sub.n--O--(CH.sub.2).sub.n,
(CH.sub.2).sub.n--C.sub.6Q.sub.4-(CH.sub.2).sub.n, and for
structure 1 additionally selected from (CH.sub.2).sub.n--O and
C(O)--O; R is selected from H, CZ.sub.3, (CZ.sub.2).sub.nCZ.sub.3,
OH, O--(O)CCH.sub.3, (CH.sub.2CH.sub.2O).sub.nCH.sub.3,
(CH.sub.2).sub.n--C.sub.6Q.sub.5, cinnamate or p-methoxy-cinnamate,
coumarin, phenyl-3-indene, epoxide,
C.ident.C--Si(C.sub.2H.sub.5).sub.3 or
C.ident.C--Si(i-C.sub.2H.sub.5).sub.3, each n is independently an
integer from 0 to 12, p is an integer from 1-6, C.sub.6Q.sub.4 and
C.sub.6Q.sub.5 denote benzene that is substituted with Q, Q is
independently H, F, CH.sub.3, CF.sub.3 or OCH.sub.3, Z is
independently H or F, with the proviso that -A-R does not contain
an --O--O-- (peroxy) linkage, and R'' is independently H or
CH.sub.3.
[0080] Further exemplary repeating units represented by Formula I,
as described above, are formed from one or more norbornene-type
monomers that include, but are not limited to, those selected from
the following formulae:
##STR00008## ##STR00009## ##STR00010## ##STR00011## ##STR00012##
##STR00013## ##STR00014##
[0081] where "Me" means methyl, "Et" means ethyl, "OMe-p" means
para-methoxy, "Ph" and "C.sub.6H.sub.5" mean phenyl,
"C.sub.6H.sub.4" means phenylene, "C.sub.6F.sub.5" means
pentafluorophenyl, in subformulae 9 and 11 "OAc" means acetate, in
sub-formula 25 "PFAc" means --OC(O)--C.sub.7F.sub.15, and for each
of the above subformulae having a methylene bridging group (a
CH.sub.2 covalently bonded to both the norbornene ring and a
functional group), including but not limited to 11-14, 16, 18, 19
and 54, it will be understood that the methylene bridging group can
be replaced by a covalent bond or --(CH.sub.2).sub.b-- as in
formula 20, and b is an integer from 1 to 6.
[0082] It will be further noted that while 55 specific examples are
provided above, other monomers in accordance with embodiments of
the present invention are inclusive of monomers represented by
formula Ia where at least one of R.sup.1, R.sup.2, R.sup.3 and
R.sup.4 are hydrocarbyls, halohydrocarbyls, and perhalocarbyls,
inclusive of heteroatoms, that include,
--(CH.sub.2).sub.n--Ar--(CH.sub.2).sub.n--C(CF.sub.3).sub.2--OH,
--(CH.sub.2).sub.n--Ar--(CH.sub.2).sub.n--OCH.sub.2C(CF.sub.3).sub.2--OH,
--(CH.sub.2).sub.n--C(CF.sub.3).sub.2--OH,
--((CH.sub.2).sub.i--O--).sub.b--(CH.sub.2)--C(CF.sub.3).sub.2--OH,
--(CH.sub.2).sub.n--C(CF.sub.3)(CH.sub.3)--OH,
(CH.sub.2).sub.n--C(O)NHR*, (CH.sub.2).sub.n--C(O)Cl,
--(CH.sub.2).sub.n--C(O)OR*, (CH.sub.2).sub.n--OR*,
--(CH.sub.2).sub.n--OC(O)R* and --(CH.sub.2).sub.n--C(O)R*, where n
independently represents an integer from 0 to 12, i is 2, 3 or 4, k
is 1, 2 or 3, Ar is aryl, for example phenyl, and R* independently
represents hydrogen, a C.sub.1-C.sub.11 alkyl, a C.sub.1-C.sub.11
halogenated or perhalogenated alkyl, a C.sub.2-C.sub.10 alkenyl, a
C.sub.2-C.sub.10 alkynyl, a C.sub.5-C.sub.12 cycloalkyl, a
C.sub.6-C.sub.14 aryl, a C.sub.6-C.sub.14 halogenated or
perhalogenated aryl, a C.sub.7-C.sub.14 aralkyl or a halogenated or
perhalogenated C.sub.7-C.sub.14 aralkyl. Exemplary perhalogenated
alkyl groups include, but are not limited to, trifluoromethyl,
trichloromethyl, --C.sub.2F.sub.5, --C.sub.3F.sub.7,
--C.sub.4F.sub.9, --C.sub.7F.sub.15, and --C.sub.11F.sub.23.
Exemplary halogenated or perhalogenated aryl and aralkyl groups
include, but are not limited groups having the formula
--(CH.sub.2).sub.x--C.sub.6F.sub.yH.sub.5-y, and
--(CH.sub.2).sub.x--C.sub.6F.sub.yH.sub.4-y-pC.sub.zF.sub.qH.sub.2z+1-q,
where x, y, q, and z are independently selected integers from 0 to
5, 0 to 5, 0 to 9, and 1 to 4, respectively. Specifically, such
exemplary halogenated and perhalogenated aryl groups include, but
are not limited to, pentachlorophenyl, pentafluorophenyl,
pentafluorobenzyl, 4-trifluoromethylbenzyl, pentafluorophenylethyl,
pentafluorophenpropyl, and pentafluorophenbutyl.
[0083] While each Formula I and Ia, as well as each of the
subformulae and generic formulae provided above are depicted
without indication of any stereochemistry, it should be noted that
generally each of the monomers, unless indicated otherwise, are
obtained as diastereomeric mixtures that retain their configuration
when converted into repeating units. As the exo- and endo-isomers
of such diastereomeric mixtures can have slightly different
properties, it should be further understood that embodiments of the
present invention are made to take advantage of such differences by
using monomers that are either a mixture of isomers that is rich in
either the exo- or endo-isomer, or are essentially the pure
advantageous isomer.
[0084] Another embodiment of the present invention is directed to
polymers of Formula I that comprise repeating units where one of
R.sup.1-4, for example R.sup.1, is a fluorinated or perfluorinated
alkyl, aryl or aralkyl group as described above and the others of
R.sup.1-4 are H. Another embodiment of this invention, R.sup.1 is
selected from one of the above subformulae 15-26 and in one
embodiment from subformulae 15, 16, 17, 18, 19 or 20
(NBC.sub.4F.sub.9, NBCH.sub.2C.sub.6F.sub.5, NBC.sub.6F.sub.5,
NBCH.sub.2C.sub.6H.sub.3F.sub.2, NBCH.sub.2C.sub.6H.sub.4CF.sub.3,
and NBalkylC.sub.6F.sub.5).
[0085] Another embodiment of the present invention is directed to
polymers of Formula I that have repeating units where one of
R.sup.1-4, for example R.sup.1, is a photoreactive or crosslinkable
group as described above and the others of R.sup.1-4 are H. R.sup.1
is a group as shown in one of the above subformulae 27-50 and as
shown in subformulae 34, 35, 36, 37 and 38 (DMMIMeNB, DMMIEtNB,
DMMIPrNB, DMMIBuNB and DMMIHxNB).
[0086] Another embodiment of the present invention is directed to
polymers of Formula I that have repeating units where one of
R.sup.1-4, for example R.sup.1, is a pendant silyl group
represented by --(CH.sub.2).sub.n--SiR.sup.93 where n is an integer
from 0 to 12, R.sup.9 independently represents halogen selected
from the group consisting of chlorine, fluorine, bromine and
iodine, linear or branched (C.sub.1 to C.sub.20)alkyl, linear or
branched (C.sub.1 to C.sub.20)alkoxy, substituted or unsubstituted
(C.sub.6 to C.sub.20)aryl, linear or branched (C.sub.1 to
C.sub.20)alkyl carbonyloxy, substituted or unsubstituted (C.sub.6
to C.sub.20)aryloxy; linear or branched (C.sub.1 to C.sub.20)
dialkylamido; substituted or unsubstituted (C.sub.6-C.sub.20)
diarylamido; substituted or unsubstituted
(C.sub.1-C.sub.20)alkylarylamido.
[0087] Another embodiment of the present invention is directed to
polymers of Formula I that have repeating units where one of
R.sup.1-4, for example R.sup.1, is a polar group having a hydroxy,
carboxy, acetoxy or oligoethyleneoxy moiety as described above and
the others of R.sup.1-4 denote H. Preferably R.sup.1 is a group as
shown in one of the above subformulae 9-14, and generally of
subformula 9 (MeOAcNB).
[0088] Another embodiment of the present invention is directed to a
polymer having a first type of repeating unit selected from
fluorinated repeating units as described above and a second type of
repeating unit selected from crosslinkable repeating units, also as
described above. Polymers of this embodiment include polymers
having a first type of repeating unit selected from subformulae 15,
16, 17, 18, 19 and 20 (NBC.sub.4F.sub.9, NBCH.sub.2C.sub.6F.sub.5,
NBC.sub.6F.sub.5, NBCH.sub.2C.sub.6F.sub.2,
NBCH.sub.2C.sub.6H.sub.4CF.sub.3, NBalkylC.sub.6F.sub.5), and a
second type of repeating unit selected from subformulae 34, 35, 36,
37 and 38 (DMMIMeNB, DMMIEtNB, DMMIPrNB, DMMIBuNB, DMMIHxNB).
[0089] Another embodiment of the present invention is directed to a
polymer having a first type of repeating unit selected from
crosslinkable repeating units as described above and a second type
of repeating unit selected from repeating units having a pendant
silyl group, also as described above. Polymers of this embodiment
include polymers having a first type of repeating unit selected
from subformulae 34, 35, 36, 37 and 38 (DMMIMeNB, DMMIEtNB,
DMMIPrNB, DMMIBuNB, DMMIHxNB), and a second type of repeating unit
selected from subformulae 53 and 54 (TMSNB, TESNB).
[0090] Another embodiment of the present invention is directed to a
polymer having a first type of repeating unit selected from
fluorinated repeating units as described above, a second type of
repeating unit selected from crosslinkable repeating units, also as
described above and a third type of repeating unit selected from
polar repeating units, again as described above. Polymers of this
embodiment include polymers having a first repeating unit of
subformula 9 (MeOAcNB), a second type of repeating unit selected
from subformulae 34, 35, 36, 37, or 38 (DMMIMeNB, DMMIEtNB,
DMMIPrNB, DMMIBuNB, DMMIHxNB), and a third type of repeating unit
selected from subformula 16 (NBCH.sub.2C.sub.6F.sub.5).
[0091] Another embodiment of the present invention is directed to a
polymer having more than three different types of repeating units
in accordance with Formula I. Another embodiment of the present
invention is directed to a polymer blend of a first polymer having
a first type of repeating unit in accordance with Formula I, and a
second polymer having, at least, a first type of repeating unit and
a second type of repeating unit in accordance with Formula I that
is distinct from the first type. Alternatively such polymer blends
can encompass the aforementioned second polymer mixed with an
alternative first polymer having two or more distinct types of
repeat units in accordance with Formula I. Alternatively, such
polymer blends can encompass the aforementioned alternative first
polymer mixed with an alternative second polymer having three
distinct types of repeat units in accordance with Formula I.
[0092] Another embodiment of the present invention is directed to a
polymer having a first and a second distinct type of repeat units
in accordance with Formula I where the ratio of such first and
second type of repeat units is from 95:5 to 5:95. In another
embodiment the ratio of such first and second type of repeat units
is from 80:20 to 20:80. In still another embodiment the ratio of
such first and second type of repeat units is from 60:40 to 40:60.
In yet another embodiment the ratio of such first and second type
of repeat units is from 55:45 to 45:55.
[0093] Another embodiment of the present invention encompasses a
polymer blend of one or more polymers each having at least one type
of repeat unit in accordance with Formula I and one or more
polymers having repeat units that are different from
norbornene-type repeat units. These other polymers are selected
from polymers including but not limited to poly(methyl
methacrylate) (PMMA), polystyrene (PS), poly-4-vinylphenol,
polyvinylpyrrolidone, or combinations thereof, like PMMA-PS and
-polyacrylonitrile (PAN).
[0094] Examples of suitable norbornene monomers, polymers and
methods for their synthesis are provided herein and can also be
found in U.S. Pat. No. 5,468,819 B2, U.S. Pat. No. 6,538,087 B2, US
2006/0020068 A1, US 2007/0066775 A1, US 2008/0194740 A1,
PCT/EP2011/004281, U.S. Ser. No. 13/223,784, PCT/EP2011/004282,
U.S. Pat. No. 6,723,486 B2, U.S. Pat. No. 6,455,650 B2 and U.S.
Ser. No. 13/223,884, which are incorporated into this application
by reference. For example, exemplary polymerizations processes
employing Group VIII transition metal catalysts are described in
the aforementioned US 2006/0020068 A1.
[0095] The polymer embodiments of the present invention are formed
having a weight average molecular weight (M.sub.w) that is
appropriate to their use. Generally, a M.sub.w from 5,000 to
500,000 is found appropriate for some embodiments, while for other
embodiments other M.sub.w ranges can be advantageous. For example,
in a embodiment, the polymer has a M.sub.w of at least 30,000,
while in another embodiment the polymer has a M.sub.w of at least
60,000. In another embodiment, the upper limit of the polymer's
M.sub.w is up to 400,000, while in another embodiment the upper
limit of the polymer's M.sub.w is up to 250,000. It will be
understood that since an appropriate M.sub.w is a function of the
desired physical properties in the cured polymer, films, layers or
structures derived therefrom, it is a design choice and thus any
M.sub.w within the ranges provided above is within the scope of the
present invention.
[0096] In an embodiment of the present invention, a crosslinkable
or crosslinked polymer is used. It has been found that such a
crosslinkable or crosslinked polymer can serve to improve one or
more properties selected from structural integrity, durability,
mechanical resistivity and solvent resistivity of the gate
dielectric layer and the electronic device. Suitable crosslinkable
polymers are for example those having one or more repeating units
of Formula I wherein one or more of R.sup.1-4 denotes a
crosslinkable group, units formed by monomers selected from
subformulae 27-50.
[0097] For crosslinking, the polymer, generally after deposition
thereof, is exposed to electron beam or electromagnetic (actinic)
radiation such as X-ray, UV or visible radiation, or heated if it
contains thermally crosslinkable groups. For example, actinic
radiation may be employed to image-wise expose the polymer using a
wavelength of from 11 nm to 700 nm, such as from 200 to 700 nm. A
dose of actinic radiation for exposure is generally from 25 to
15,000 mJ/cm.sup.2. Suitable radiation sources include mercury,
mercury/xenon, mercury/halogen and xenon lamps, argon or xenon
laser sources, x-ray. Such exposure to actinic radiation causes
crosslinking in exposed regions. Although other repeating unit
pendant groups that crosslink can be provided, generally such
crosslinking is provided by repeating units that encompass a
maleimide pendant group, that is to say one of R.sup.1 to R.sup.4
is a substituted or unsubstituted maleimide moiety. If it is
desired to use a light source having a wavelength outside of the
photo-absorption band of the maleimide group, a radiation sensitive
photosensitizer can be added. If the polymer contains thermally
crosslinkable groups, optionally an initiator may be added to
initiate the crosslinking reaction, for example in case the
crosslinking reaction is not initiated thermally.
[0098] In one embodiment, the planarization layer is post exposure
baked at a temperature from 70.degree. C. to 130.degree. C., for
example for a period of from 1 to 10 minutes. Post exposure bake
can be used to further promote crosslinking of crosslinkable
moieties within exposed portions of the polymer.
[0099] In another embodiment, the crosslinkable polymer composition
comprises a stabilizer material or moiety to prevent spontaneous
crosslinking and improve shelf life of the polymer composition.
Suitable stabilizers are antioxidants such as catechol or phenol
derivatives that optionally contain one or more bulky alkyl groups,
for example t-butyl groups, in ortho-position to the phenolic OH
group.
[0100] In order to improve the processing of the functional layers
and the integrity of the electronic device, it is desirable to
decrease the time needed for the process while keeping or improving
the physical properties of the layers being formed. This can be
maintained where subsequent layers and solvents used in forming
such layers are orthogonal and thus do not dissolve each other.
Where such orthogonality is difficult to obtain, crosslinking,
typically UV crosslinking, a first functional layer to make such
first layer insoluble with respect to the polymer composition of a
second functional layer will prevent any influence of the
properties of either layer on the other layer.
[0101] Shortening the time needed for the processing can be done
for example by tuning the coating process, while decreasing the
time needed for UV crosslinking can be achieved both by chemical
adjustment of the polymer or by changes in the process.
[0102] However, chemical modifications of polymers are limited,
because the UV sensitivity is related to certain properties of the
polymer, and for example changes towards increased UV sensitivity
may decrease the solubility. Changing the process, for example, by
using higher power UV, could increase the possibility of creating
an ozone atmosphere and thus cause undesired changes in the surface
of the polymer.
[0103] Therefore, in some embodiments in accordance with the
present invention the polymer composition comprises one or more
crosslinker additives. Such additives comprise two or more
functional groups that are capable of reacting with the pendant
crosslinkable groups of the polycycloolefinic polymer. It will also
be understood that the use of such crosslinker additives can also
enhance the crosslinking of the aforementioned polymer.
[0104] In some embodiments in accordance with the present
invention, crosslinking can be achieved by exposure to UV
radiation.
[0105] The crosslinkable group of the crosslinker is selected from
a maleimide, a 3-monoalkyl-maleimide, a 3,4-dialkylmaleimide, an
epoxy, a vinyl, an acetylene, an indenyl, a cinnamate or a coumarin
group, or a group that comprises a substituted or unsubstituted
maleimide portion, an epoxide portion, a vinyl portion, an
acetylene portion, an indenyl portion, a cinnamate portion or a
coumarin portion.
[0106] In some embodiments in accordance with the present
invention, the crosslinker is selected of formula III1 or III2
P-A''-X'-A''-P III1
H.sub.4-cC(A''-P).sub.c III2
[0107] wherein X' is O, S, NH or a single bond, A'' is a single
bond or a connecting, spacer or bridging group, which is for
example selected from (CZ.sub.2).sub.n,
(CH.sub.2).sub.n--(CH.dbd.CH).sub.p--(CH.sub.2).sub.n,
(CH.sub.2).sub.n--O--(CH.sub.2).sub.n,
(CH.sub.2).sub.n--C.sub.6Q.sub.10-(CH.sub.2).sub.n, and C(O), where
each n is independently an integer from 0 to 12, p is an integer
from 1-6, Z is independently H or F, C.sub.6Q.sub.10 is cyclohexyl
that is substituted with Q, Q is independently H, F, CH.sub.3,
CF.sub.3, or OCH.sub.3, P is a crosslinkable group, and c is 2, 3,
or 4, and where in formula III1 at least one of X' and the two
groups A'' is not a single bond.
[0108] In one embodiment P is selected from a maleimide group, a
3-monoalkyl-maleimide group, a 3,4-dialkylmaleimide group, an epoxy
group, a vinyl group, an acetylene group, an indenyl group, a
cinnamate group or a coumarin group, or comprises a substituted or
unsubstituted maleimide portion, an epoxide portion, a vinyl
portion, an acetylene portion, an indenyl portion, a cinnamate
portion or a coumarin portion.
[0109] Suitable compounds of formula III1 are selected from formula
C1:
##STR00015##
wherein R.sup.10 and R.sup.11 are independently of each other H or
a C.sub.1-C.sub.6 alkyl group, and A'' is as defined in formula
III1. In one embodiment of this invention, the crosslinkers are
selected from DMMI-butyl-DMMI, DMMI-pentyl-DMMI and
DMMI-hexyl-DMMI, wherein "DMMI" means 3,4-dimethylmaleimide.
[0110] In one embodiment the spacer group A'' denotes linear
C.sub.1 to C.sub.30 alkylene or branched C.sub.3 to C.sub.30
alkylene or cyclic C.sub.5 to C.sub.30 alkylene, each of which is
unsubstituted or mono- or polysubstituted by F, Cl, Br, I, or CN,
wherein optionally one or more non-adjacent CH.sub.2 groups are
replaced, in each case independently from one another, by --O--,
--S--, --NH--, --NR.sup.18--, --SiR.sup.18R.sup.19--, --C(O)--,
--C(O)O--, --OC(O)--, --OC(O)--O--, --S--C(O)--, --C(O)--S--,
--CH.dbd.CH-- or --C.ident.C-- in such a manner that O and/or S
atoms are not linked directly to one another, R.sup.18 and R.sup.19
are independently of each other H, methyl, ethyl or a C.sub.3 to
C.sub.12 linear or branched alkyl group.
[0111] Suitable groups A'' are --(CH.sub.2).sub.n--,
--(CH.sub.2CH.sub.2O).sub.n--, --CH.sub.2CH.sub.2--,
--CH.sub.2CH.sub.2--S--CH.sub.2CH.sub.2-- or
--CH.sub.2CH.sub.2--NH--CH.sub.2CH.sub.2-- or
--(SiR.sup.18R.sup.19--O).sub.n--, with r being an integer from 2
to 12, s being 1, 2 or 3 and R.sup.18 and R.sup.19 having the
meanings given above.
[0112] Further groups A'' are selected from methylene, ethylene,
propylene, butylene, pentylene, hexylene, heptylene, octylene,
nonylene, decylene, undecylene, dodecylene, octadecylene,
ethyleneoxyethylene, methyleneoxybutylene, ethylene-thioethylene,
ethylene-N-methyl-iminoethylene, 1-methylalkylene, ethenylene,
propenylene, and butenylene.
[0113] The synthesis of crosslinkers like those of formula C1 is
disclosed for example in U.S. Pat. No. 3,622,321 which is
incorporated by reference into this application.
[0114] The polymer compositions generally encompass, in addition to
one or more polymer components, a casting solvent optionally having
orthogonal solubility properties with respect to the insulating
layer material and the OSC layer, an optional cross-linking agent,
an optional reactive solvent, an optional UV sensitizer, and an
optional thermal sensitizer.
[0115] In another embodiment the polymer composition used for
preparation of the planarization layer comprises a crosslinkable
polycycloolefinic polymer and a reactive adhesion promoter. The
reactive adhesion promoter comprises a first functional group that
is capable of crosslinking with the pendant crosslinkable group in
the crosslinkable polycycloolefinic polymer, and a second
functional group which is a surface-active group that is capable of
interactions, for example chemical bonding, with the functional
layer provided onto the planarization layer. The adhesion promoter
may be used especially if the functional layer provided onto the
planarization layer is a semiconducting or dielectric layer.
[0116] Suitable adhesion promoters are selected of formula IV
G-A''-P IV
[0117] wherein G is a surface-active group, preferably a silane or
silazane group, A'' is a single bond or a connecting, spacer or
bridging group, preferably as defined in formula III1 above, and P
is a crosslinkable group, preferably as defined in formula III1
above.
[0118] In one embodiment G is a group of the formula
--SiR.sup.12R.sup.13R.sup.14, or a group of the formula
--NH--SiR.sup.12R.sup.13R.sup.14, wherein R.sup.12, R.sup.13 and
R.sup.14 are each independently selected from halogen, silazane,
C.sub.1-C.sub.12-alkoxy, C.sub.1-C.sub.12-alkylamino, optionally
substituted C.sub.5-C.sub.20-aryloxy and optionally substituted
C.sub.2-C.sub.20-heteroaryloxy, and wherein one or two of R.sup.12,
R.sup.13 and R.sup.14 may also denote C.sub.1-C.sub.12-alkyl,
optionally substituted C.sub.5-C.sub.20-aryl or optionally
substituted C.sub.2-C.sub.20-heteroaryl.
[0119] In another embodiment P is selected from a maleimide, a
3-monoalkyl-maleimide, a 3,4-dialkylmaleimide, an epoxy, a vinyl,
an acetyl, an indenyl, a cinnamate or a coumarin group, or
comprises a substituted or unsubstituted maleimide portion, an
epoxide portion, a vinyl portion, an acetyl portion, an indenyl
portion, a cinnamate portion or a coumarin portion.
[0120] In another embodiment A'' is selected from (CZ.sub.2).sub.n,
(CH.sub.2).sub.n--(CH.dbd.CH).sub.p--(CH.sub.2).sub.n,
(CH.sub.2)--O, (CH.sub.2).sub.n--O--(CH.sub.2).sub.n,
(CH.sub.2).sub.n--C.sub.6Q.sub.4-(CH.sub.2).sub.n,
(CH.sub.2).sub.n--C.sub.6Q.sub.10-(CH.sub.2).sub.n and C(O)--O,
where each n is independently an integer from 0 to 12, p is an
integer from 1-6, Z is independently H or F, C.sub.6Q.sub.4 is
phenyl that is substituted with Q, C.sub.6Q.sub.10 is cyclohexyl
that is substituted with Q, Q is independently H, F, CH.sub.3,
CF.sub.3 or OCH.sub.3.
[0121] Suitable adhesion promoters are selected from formula
A1:
##STR00016##
[0122] where R.sup.12, R.sup.13 R.sup.14, and A'' are as defined
above, and R.sup.10 and R.sup.11 are each independently H or a
C.sub.1-C.sub.6 alkyl group. Suitable compounds of formula A1 are
for example DMMI-propyl-Si(OEt).sub.3, DMMI-butyl-Si(OEt).sub.3,
DMMI-butyl-Si(OMe).sub.3, DMMI-hexyl-Si(OMe).sub.3, wherein "DMMI"
means 3,4-dimethylmaleimide.
[0123] The present invention also relates to an electronic device
having or being obtained through the use of a polymer composition
according to the present invention. Such electronic devices
include, among others, field effect transistors (FETs) and organic
field effect transistors (OFETs), thin film transistors (TFT) and
organic thin film transistors (OTFTs), which can be top gate or
bottom gate transistors. For example, transistors made through the
use of a polymer composition according to the present invention are
depicted schematically in FIGS. 3 and 4.
[0124] FIG. 1 and FIG. 2 depict schematic representations of top
and bottom gate organic field effect transistors, respectively,
according to prior art. Thus the OFET device of FIG. 1 and FIG. 2
include substrate (10), source and drain electrodes (20), organic
semiconductor layer (30), gate dielectric layer (40), gate
electrode (50), and an optional passivation layer (60).
[0125] FIG. 3 is a schematic and exemplary representation of a top
gate OFET device in accordance with one embodiment of the present
invention. Such OFET device includes substrate (10), planarization
layer (70), which is derived from a polymer composition
encompassing a polycycloolefinic polymer or blend of
polycycloolefinic polymer as described above and below, source and
drain electrodes (20), organic semiconductor layer (30), gate
electrode (50), gate dielectric layer (40), and optional layer
(60), which is for example a layer having one or more of
insulating, protecting, stabilizing and adhesive function, and
which is disposed overlying gate electrode (50) and gate dielectric
layer (40).
[0126] Another subject of the present invention is a process for
preparing a top gate OFET device, for example as illustrated in
FIG. 3, by a) depositing a layer of planarization material (70),
which comprises a polycycloolefinic polymer or a polymer blend or
polymer composition comprising a polycycloolefinic polymer as
described above and below, on a substrate (10), b) forming source
and drain electrodes (20) on at least a portion of planarization
layer (70) as depicted, c) depositing a layer of organic
semiconductor material (30) over the previously deposited
planarization layer (70) and source and drain electrodes (20), d)
depositing a layer of dielectric material (40) on organic
semiconductor layer (30), e) forming gate electrode (50) on at
least a portion of dielectric layer (40) as depicted, and f)
optionally depositing layer (60), which is for example an
insulating and/or protection and/or stabilizing and/or adhesive
layer, on the gate electrode (50) and portions of dielectric layer
(40).
[0127] FIG. 4 is a schematic and exemplary representation of a
bottom gate OFET device in accordance with an embodiment of the
present invention. Such OFET device includes substrate (10),
planarization layer (70), which is derived from a polymer
composition encompassing a polycycloolefinic polymer or blend of
polycycloolefinic polymer as described above and below, source and
drain electrodes (20), organic semiconductor layer (30), gate
electrode (50), gate dielectric layer (40), and optional second
insulator layer (60), which is a passivation or protection layer to
shield the source and drain electrodes (20) from further layers or
devices provided on top of the device.
[0128] Another subject of the present invention is a process for
preparing a bottom gate OFET device, for example as illustrated in
FIG. 4, by a) depositing a layer of planarization material (70),
which comprises a polycycloolefinic polymer or a polymer blend or
polymer composition comprising a polycycloolefinic polymer as
described above and below, on a substrate (10), b) forming gate
electrode (50) on at least a portion of planarization layer (70) as
depicted, c) depositing a layer of dielectric material (40) over
the previously deposited planarization layer (70) and gate
electrode (50), d) depositing a layer of organic semiconductor
material (30) on dielectric layer (40), e) forming source and drain
electrodes (20) on at least a portion of organic semiconductor
layer (40) as depicted, and f) optionally depositing layer (60),
which is for example an insulating and/or protection and/or
stabilizing and/or adhesive layer, on the source and drain
electrodes (20) and portions of organic semiconductor layer
(30).
[0129] The aforementioned processes for preparing a transistor are
another subject of the present invention.
[0130] Deposition and/or forming of the layers and structures of
the OFET embodiments in accordance with the present invention are
performed using solution processing techniques where such
techniques are possible. For example a formulation or composition
of a material, typically a solution encompassing one or more
organic solvents, can be deposited or formed using techniques that
include, but are not limited to, dip coating, spin coating, slot
die coating, ink jet printing, letter-press printing, screen
printing, doctor blade coating, roller printing, reverse-roller
printing, offset lithography printing, flexographic printing, web
printing, spray coating, brush coating, or pad printing, followed
by the evaporation of the solvent employed to form such a solution.
For example, an organic semiconductor material and an organic
dielectric material can each be deposited or formed by spin
coating, flexographic printing, and inkjet printing techniques in
an order appropriate to the device being formed. In one embodiment
of this invention slot die coating can be employed.
[0131] Specifically, where planarization layer (70) is deposited by
solution processing and employing a solution of one or more of the
polymer or polymer blends as described above and below in one or
more organic solvents, such solvents are preferably selected from,
but not limited to, organic ketones such as methyl ethyl ketone
(MEK), 2-heptanone (MAK), cyclohexanone, cyclopentanone, and ethers
such as butyl-phenyl ether, 4-methylanisole and aromatic
hydrocarbons such as cyclohexylbenzene, or mixtures thereof. In one
embodiment, the total concentration of the polymer material in the
formulation is from 0.1-25 wt. % although other concentrations can
also be appropriate. Organic ketone solvents with a high boiling
point have been found to be especially suitable and preferred
solvents where inkjet and flexographic printing techniques are
employed.
[0132] The planarization layer (70) should be applied with an
appropriate thickness to provide sufficient wetting and adhesion
for any additional layers coated thereon while not negatively
affecting device performance. While the appropriate thickness of
planarization layer (70) used in fabricating a device is a function
of the specific device being made and the ultimate use of such a
device, among other things, as general guidelines it has been found
that a preferred thickness in the range of from 0.1 to 10 microns.
It will be understood, however, that other thickness ranges may be
appropriate and thus are within the scope of the present
invention.
[0133] In other embodiments of the present invention, a
crosslinkable or crosslinked polymer is used as the planarization
layer material or as a component thereof. It has been found that
such a crosslinkable or crosslinked polymer can serve to improve
one or more properties selected from structural integrity,
durability and solvent resistance of the planarization layer and
the electronic device. Very suitable and preferred crosslinkable
polymers are for example those having one or more repeating units
of Formula I wherein one or more of R.sup.1-4 denotes a
crosslinkable group, very preferably units of subformulae
27-50.
[0134] For crosslinking, the polymer, generally after deposition
thereof, is exposed to electron beam or electromagnetic (actinic)
radiation such as X-ray, UV or visible radiation, or heated if it
contains thermally crosslinkable groups. For example, actinic
radiation may be employed to image the polymer using a wavelength
of from 11 nm to 700 nm, such as from 200 to 700 nm. A dose of
actinic radiation for exposure is generally from 25 to 15,000
mJ/cm.sup.2. Suitable radiation sources include mercury,
mercury/xenon, mercury/halogen and xenon lamps, argon or xenon
laser sources, or X-ray. Such exposure to actinic radiation is to
cause crosslinking in exposed regions. Although other repeating
unit pendant groups that crosslink can be provided, generally such
crosslinking is provided by repeating units that encompass a
maleimide pendant group, that is to say one of R.sup.1 to R.sup.4
is a substituted or unsubstituted maleimide moiety. If it is
desired to use a light source having a wavelength outside of the
photo-absorption band of the maleimide group, a radiation sensitive
photosensitizer can be added. If the polymer contains thermally
crosslinkable groups, optionally an initiator may be added to
initiate the crosslinking reaction, for example in case the
crosslinking reaction is not initiated thermally.
[0135] In an embodiment, the planarization layer is post exposure
baked at a temperature from 70.degree. C. to 130.degree. C., for
example for a period of from 1 to 10 minutes. Post exposure bake
can be used to further promote crosslinking of crosslinkable
moieties within exposed portions of the polymer.
[0136] The other components or functional layers of the electronic
device, like the substrate, the gate and source and drain
electrodes, and organic semiconductor layer, can be selected from
standard materials, and can be manufactured and applied to the
device by standard methods. Suitable materials and manufacturing
methods for these components and layers are known to a person
skilled in the art and are described in the literature. Exemplary
deposition methods include the liquid coating methods previously
described as well as chemical vapor deposition (CVD) or physical
vapor deposition methodologies.
[0137] Generally the thickness of a functional layer, for example a
gate dielectric or organic semiconductor layer, in some electronic
device embodiments according to the present invention is from 0.001
(in case of a monolayer) to 10 .mu.m; In other embodiments such
thickness ranges from 0.001 nm to 1 .mu.m, and in still other
embodiments from 5 nm to 500 nm, although other thicknesses or
ranges of thickness are contemplated and thus are within the scope
of the present invention.
[0138] Various substrates may be used for the fabrication of the
electronic device embodiments of the present invention. For example
glass or polymeric materials are most often used. In other
embodiments, polymeric materials include, but are not limited to,
alkyd resins, allyl esters, benzocyclobutenes, butadiene-styrene,
cellulose, cellulose acetate, epoxy polymers,
ethylene-chlorotrifluoro ethylene copolymers,
ethylene-tetra-fluoroethylene copolymers, fiber glass enhanced
thermoplastic, fluorocarbon polymers,
hexafluoropropylenevinylidene-fluoride copolymer, polyethylene,
parylene, polyamide, polyimide, polyaramid, polydimethylsiloxane,
polyethersulphone, polyethylenenaphthalate,
polyethyleneterephthalate, polyketone, polymethylmethacrylate,
polypropylene, polystyrene, polysulphone, polytetrafluoroethylene,
polyurethanes, polyvinylchloride, polycycloolefin, silicone
rubbers, and silicones, where polyethyleneterephthalate, polyimide,
polycycloolefin and polyethylenenaphthalate materials have been
found most appropriate. Additionally, for some embodiments of the
present invention the substrate can be any thermoplastic, metal or
glass material coated with one or more of the above listed
materials.
[0139] In one embodiment, the substrate is a polymer film of a
polymer selected from the group consisting of polyesters,
polyimides, polyarylates, polycycloolefins, polycarbonates and
polyethersulphones.
[0140] In other embodiments, polyester substrates, most preferably
polyethylene terephthalate (PET) or polyethylene naphthalate (PEN),
for example PET films of the Melinex.RTM. series or PEN films of
the Teonex.RTM. series, both from DuPont Teijin Films.TM. may be
used.
[0141] The gate, source and drain electrodes of the OFET device
embodiments in accordance with the present invention can be
deposited or formed by liquid coating, such as spray-, dip-, web-
or spin-coating, or by vacuum deposition methods, including but not
limited to physical vapor deposition (PVD), chemical vapor
deposition (CVD) or thermal evaporation. Suitable electrode
materials and deposition methods are known to the person skilled in
the art. Suitable electrode materials include, without limitation,
inorganic or organic materials, or composites of the two. Exemplary
electrode materials include polyaniline, polypyrrole,
poly(3,4-ethylene-dioxythiophene) (PEDOT) or doped conjugated
polymers, further dispersions or pastes of graphite or graphene or
particles of metal such as Au, Ag, Cu, Al, Ni or their mixtures as
well as sputter coated or evaporated metals such as Cu, Cr, Pt/Pd,
Ag, Au or metal oxides such as indium tin oxide (ITO), F-doped ITO
or Al-doped ZnO. Organometallic precursors may also be used and
deposited from a liquid phase.
[0142] The organic semiconductor materials and methods for applying
the organic semiconductor layer for OFET embodiments in accordance
with the present invention can be selected from standard materials
and methods known to the person skilled in the art, and are
described in the literature. The organic semiconductor can be an n-
or p-type OSC, which can be deposited by PVD, CVD or solution
deposition methods. Effective OSCs exhibit a FET mobility of
greater than 1.times.10.sup.-5 cm.sup.2V.sup.-1s.sup.-1.
[0143] OSC embodiments in accordance with the present invention can
be either OFETs where the OSC is used as the active channel
material, OPV devices where the OSC is used as charge carrier
material, or organic rectifying diodes (ORDs) where the OSC is a
layer element of such a diode. OSCs for such embodiments can be
deposited by any of the previously discussed deposition methods,
but as they are generally deposited or formed as blanket layers,
solvent coated methods such as spray-, dip-, web- or spin-coating,
or printing methods such as ink-jet printing, flexo printing or
gravure printing, are typically employed to allow for ambient
temperature processing. However, OSCs can be deposited by any
liquid coating technique, for example ink-jet deposition or via PVD
or CVD techniques.
[0144] For some OFET embodiments, the semiconducting layer that is
formed can be a composite of two or more of the same or different
types of organic semiconductors. For example, a p-type OSC material
may, for example, be mixed with an n-type material to achieve a
doping effect of the layer. In some embodiments of the invention,
multilayer organic semiconductor layers are used. For example an
intrinsic organic semiconductor layer can be deposited near the
gate dielectric interface and a highly doped region can
additionally be coated adjacent to such an intrinsic layer.
[0145] The OSC material employed for electronic device embodiments
in accordance with the present invention can be any conjugated
molecule, for example an aromatic molecule containing preferably
two or more, very preferably at least three aromatic rings. In some
embodiments of the present invention, the OSC contains aromatic
rings selected from 5-, 6- or 7-membered aromatic rings, while in
other embodiments the OSC contains aromatic rings selected from 5-
or 6-membered aromatic rings. The OSC material may be a monomer,
oligomer or polymer, including mixtures, dispersions and blends of
one or more of monomers, oligomers or polymers.
[0146] Each of the aromatic rings of the OSC optionally contains
one or more hetero atoms selected from Se, Te, P, Si, B, As, N, O
or S, generally from N, O or S. Further, the aromatic rings may be
optionally substituted with alkyl, alkoxy, polyalkoxy, thioalkyl,
acyl, aryl or substituted aryl groups, halogen, where fluorine,
cyano, nitro or an optionally substituted secondary or tertiary
alkylamine or arylamine represented by --N(R.sup.15)(R.sup.16),
where R.sup.15 and R.sup.16 are each independently H, an optionally
substituted alkyl or an optionally substituted aryl, alkoxy or
polyalkoxy groups are typically employed. Further, where R.sup.15
and R.sup.16 is alkyl or aryl these may be optionally
fluorinated.
[0147] The aforementioned aromatic rings can be fused rings or
linked with a conjugated linking group such as
--C(T.sub.1)=C(T.sub.2)-, --C.ident.C--, --N(R''')--, --N.dbd.N--,
(R''').dbd.N--, --N.dbd.C(R''')--, where T.sub.1 and T.sub.2 each
independently represent H, Cl, F, --C.ident.N or lower alkyl groups
such as C.sub.1-4 alkyl groups; R''' represents H, optionally
substituted alkyl or optionally substituted aryl. Further, where
R''' is alkyl or aryl can be fluorinated.
[0148] In some preferred electronic device embodiments of the
present invention, OSC materials that can be used include
compounds, oligomers and derivatives of compounds selected from the
group consisting of conjugated hydrocarbon polymers such as
polyacene, polyphenylene, poly(phenylene vinylene), polyfluorene
including oligomers of those conjugated hydrocarbon polymers;
condensed aromatic hydrocarbons, such as, tetracene, chrysene,
pentacene, pyrene, perylene, coronene, or soluble, substituted
derivatives of these; oligomeric para substituted phenylenes such
as p-quaterphenyl (p-4P), p-quinquephenyl (p-5P), p-sexiphenyl
(p-6P), or soluble substituted derivatives of these; conjugated
heterocyclic polymers such as poly(3-substituted thiophene),
poly(3,4-bisubstituted thiophene), optionally substituted
polythieno[2,3-b]thiophene, optionally substituted
polythieno[3,2-b]thiophene, poly(3-substituted selenophene),
polybenzothiophene, polyisothianapthene, poly(N-substituted
pyrrole), poly(3-substituted pyrrole), poly(3,4-bisubstituted
pyrrole), polyfuran, polypyridine, poly-1,3,4-oxadiazoles,
polyisothianaphthene, poly(N-substituted aniline),
poly(2-substituted aniline), poly(3-substituted aniline),
poly(2,3-bisubstituted aniline), polyazulene, polypyrene;
pyrazoline compounds; polyselenophene; polybenzofuran; polyindole;
polypyridazine; benzidine compounds; stilbene compounds; triazines;
substituted metallo- or metal-free porphines, phthalocyanines,
fluorophthalocyanines, naphthalocyanines or
fluoronaphthalocyanines; C.sub.60 and C.sub.70 fullerenes;
N,N'-dialkyl, substituted dialkyl, diaryl or substituted
diaryl-1,4,5,8-naphthalenetetracarboxylic diimide and fluoro
derivatives; N,N'-dialkyl, substituted dialkyl, diaryl or
substituted diaryl 3,4,9,10-perylenetetracarboxylicdiimide;
bathophenanthroline; diphenoquinones; 1,3,4-oxadiazoles;
11,11,12,12-tetracyanonaptho-2,6-quinodimethane;
.alpha.,.alpha.'-bis(dithieno[3,2-b2',3'-d]thiophene); 2,8-dialkyl,
substituted dialkyl, diaryl or substituted diaryl
anthradithiophene; 2,2'-bibenzo[1,2-b:4,5-b']dithiophene. Where a
liquid deposition technique of the OSC is desired, compounds from
the above list and derivatives thereof are limited to those that
are soluble in an appropriate solvent or mixture of appropriate
solvents.
[0149] Further, in some embodiments in accordance with the present
invention, the OSC materials are polymers or copolymers that
encompass one or more repeating units selected from
thiophene-2,5-diyl, 3-substituted thiophene-2,5-diyl, optionally
substituted thieno[2,3-b]thiophene-2,5-diyl, optionally substituted
thieno[3,2-b]thiophene-2,5-diyl, selenophene-2,5-diyl, or
3-substituted selenophene-2,5-diyl.
[0150] Further p-type OSCs are copolymers comprising electron
acceptor and electron donor units. Copolymers of this embodiment
are for example copolymers comprising one or more
benzo[1,2-b:4,5-b']dithiophene-2,5-diyl units that are
4,8-disubstituted by one or more groups R as defined above, and
further comprising one or more aryl or heteroaryl units selected
from Group A and Group B, comprising at least one unit of Group A
and at least one unit of Group B, wherein Group A consists of aryl
or heteroaryl groups having electron donor properties and Group B
consists of aryl or heteroaryl groups having electron acceptor
properties, and Group A consists of selenophene-2,5-diyl,
thiophene-2,5-diyl, thieno[3,2-b]thiophene-2,5-diyl,
thieno[2,3-b]thiophene-2,5-diyl,
selenopheno[3,2-b]selenophene-2,5-diyl,
selenopheno[2,3-b]selenophene-2,5-diyl,
selenopheno[3,2-b]thiophene-2,5-diyl,
selenopheno[2,3-b]thiophene-2,5-diyl, benzo[1,2-b:
4,5-b']dithiophene-2,6-diyl, 2,2-dithiophene, 2,2-diselenophene,
dithieno[3,2-b:2',3'-d]silole-5,5-diyl,
4H-cyclopenta[2,1-b:3,4-b']dithiophene-2,6-diyl,
2,7-di-thien-2-yl-carbazole, 2,7-di-thien-2-yl-fluorene,
indaceno[1,2-b:5,6-b']dithiophene-2,7-diyl,
benzo[1'',2'':4,5;4'',5'':4',5']bis(silolo[3,2-b:3',2'-b']thiophene)-2,7--
diyl, 2,7-di-thien-2-yl-indaceno[1,2-b:5,6-b']dithiophene,
2,7-di-thien-2-yl-benzo[1'',2'':4,5;4'',5'':4',5']bis(silolo[3,2-b:3',2'--
b']thiophene)-2,7-diyl, and
2,7-di-thien-2-yl-phenanthro[1,10,9,8-c,d,e,f,g]carbazole, all of
which are optionally substituted by one or more, one or two groups
R as defined above, and Group B consists of
benzo[2,1,3]thiadiazole-4,7-diyl,
5,6-dialkyl-benzo[2,1,3]thiadiazole-4,7-diyl,
5,6-dialkoxybenzo[2,1,3]thiadiazole-4,7-diyl,
benzo[2,1,3]selenadiazole-4,7-diyl,
5,6-dialkoxy-benzo[2,1,3]selenadiazole-4,7-diyl,
benzo[1,2,5]thiadiazole-4,7,diyl,
benzo[1,2,5]selenadiazole-4,7,diyl,
benzo[2,1,3]oxadiazole-4,7-diyl,
5,6-dialkoxybenzo[2,1,3]oxadiazole-4,7-diyl,
2H-benzotriazole-4,7-diyl, 2,3-dicyano-1,4-phenylene, 2,5-dicyano,
1,4-phenylene, 2,3-difluoro-1,4-phenylene,
2,5-difluoro-1,4-phenylene, 2,3,5,6-tetrafluoro-1,4-phenylene,
3,4-difluorothiophene-2,5-diyl, thieno[3,4-b]pyrazine-2,5-diyl,
quinoxaline-5,8-diyl, thieno[3,4-b]thiophene-4,6-diyl,
thieno[3,4-b]thiophene-6,4-diyl,
3,6-pyrrolo[3,4-c]pyrrole-1,4-dione, all of which are optionally
substituted by one or more, preferably one or two groups R as
defined above.
[0151] In other embodiments of the present invention, the OSC
materials are substituted oligoacenes such as pentacene, tetracene
or anthracene, or heterocyclic derivatives thereof.
Bis(trialkylsilylethynyl)oligoacenes or
bis(trialkylsilylethynyl)heteroacenes, as disclosed for example in
U.S. Pat. No. 6,690,029 or WO 2005/055248 A1 or U.S. Pat. No.
7,385,221, are incorporated by reference into this application, are
also useful.
[0152] Where appropriate and needed to adjust the rheological
properties as described for example in WO 2005/055248 A1, some
embodiments of the present invention employ OSC compositions that
include one or more organic binders.
[0153] The binder, which is typically a polymer, may comprise
either an insulating binder or a semiconducting binder, or mixtures
thereof may be referred to herein as the organic binder, the
polymeric binder, or simply the binder.
[0154] Preferred binders according to the present invention are
materials of low permittivity, that is, those having a permittivity
c of 3.3 or less. The organic binder preferably has a permittivity
c of 3.0 or less, more preferably 2.9 or less. Preferably the
organic binder has a permittivity c at of 1.7 or more. It is
especially preferred that the permittivity of the binder is in the
range from 2.0 to 2.9. Whilst not wishing to be bound by any
particular theory it is believed that the use of binders with a
permittivity c of greater than 3.3, may lead to a reduction in the
OSC layer mobility in an electronic device, for example an OFET. In
addition, high permittivity binders could also result in increased
current hysteresis of the device, which is undesirable.
[0155] Examples of a suitable organic binders include polystyrene,
or polymers or copolymers of styrene and .alpha.-methyl styrene, or
copolymers including styrene, .alpha.-methylstyrene and butadiene
may suitably be used. Further examples of suitable binders are
disclosed for example in US 2007/0102696 A1 is incorporated by
reference into this application.
[0156] In one type of embodiment, the organic binder is one in
which at least 95%, in an other embodiment at least 98% and another
embodiment when all of the atoms consist of hydrogen, fluorine and
carbon atoms.
[0157] The binder is preferably capable of forming a film, more
preferably a flexible film.
[0158] The binder can also be selected from crosslinkable binders,
such as acrylates, epoxies, vinylethers, and thiolenes, preferably
having a sufficiently low permittivity, very preferably of 3.3 or
less. The binder can also be mesogenic or liquid crystalline.
[0159] In another embodiment the binder is a semiconducting binder,
which contains conjugated bonds, especially conjugated double bonds
and/or aromatic rings. Suitable and preferred binders are for
example polytriarylamines as disclosed for example in U.S. Pat. No.
6,630,566.
[0160] The proportions of binder to OSC is typically 20:1 to 1:20
by weight, preferably 10:1 to 1:10 more preferably 5:1 to 1:5,
still more preferably 3:1 to 1:3 further preferably 2:1 to 1:2 and
especially 1:1. Dilution of the compound of formula I in the binder
has been found to have little or no detrimental effect on the
charge mobility, in contrast to what would have been expected from
the prior art.
[0161] Unless the context clearly indicates otherwise, as used
herein plural forms of the terms herein are to be construed as
including the singular form and vice versa.
[0162] It will be appreciated that variations to the foregoing
embodiments of the invention can be made while still falling within
the scope of the invention. Each feature disclosed in this
specification, unless stated otherwise, may be replaced by
alternative features serving the same, equivalent or similar
purpose. Thus, unless stated otherwise, each feature disclosed is
one example only of a generic series of equivalent or similar
features.
[0163] All of the features disclosed in this specification may be
combined in any combination, except combinations where at least
some of such features and/or steps are mutually exclusive. In
particular, the features of the invention are applicable to all
aspects of the invention and may be used in any combination.
Likewise, features described in non-essential combinations may be
used separately (not in combination).
[0164] The invention will now be described in more detail by
reference to the following examples, which are illustrative only
and do not limit the scope of the invention.
[0165] Above and below, unless stated otherwise percentages are
percent by weight and temperatures are given in degrees Celsius
(.degree. C.). The values of the dielectric constant .di-elect
cons. ("permittivity") refer to values taken at 1,000 Hz and
20.degree. C.
[0166] Unless stated otherwise, the values of the surface energy
refer to those calculated from contact angle measurement of the
polymers according to the method described in D. K. Owens, R. C.
Wendt, "Estimation of the surface free energy of polymers", Journal
of Applied Polymer Science, Vol. 13, 1741-1747, 1969 or "Surface
and Interfacial Tension: Measurement, Theory, and Applications
(Surfactant Science Series Volume 119)" by Stanley Hartland
(Editor), Taylor & Francis Ltd; 2004 (ISBN: 0-8247-5034-9),
chapter 7, p.: 375: "Contact Angle and Surface Tension Measurement"
by Kenji Katoh).
Comparison Example 1
Top Gate OFET with Teonex.RTM. PEN Film as Substrate
[0167] Teonex Q65FA.RTM. PEN film (available from DuPont Teijin
Films.TM.) was washed in methanol and treated with argon plasma for
3 min (microwave plasma generator, power: 100 W, argon flow: 500
ml/min) in order to increase surface energy of the substrate.
[0168] 60 nm thick gold source drain electrodes were evaporated
directly onto the PEN substrate with a parallel plate geometry of
20 .mu.m wide by 1 mm long.
[0169] The electrodes were treated with Lisicon M001.RTM.
(available from Merck Chemicals Ltd.) by spin coating from
isopropyl alcohol and evaporating the excess off on a hot plate at
70.degree. C. for 2 min.
[0170] An OSC Lisicon S1200-Series.RTM. formulation was used
(available from Merck Chemicals Ltd.).
[0171] The OSC formulation was then printed as a 5.times.5 cm wide
area block on the array of source/drain electrodes on the film as
described above using a RK Flexiproof 100 flexographic printing
with a 8 cm.sup.3/m.sup.2 loaded anilox and a Cyrel HiQS flexo mat
running at 70 m/min speed. The printed OSC layer was then annealed
at 70.degree. C. for 5 min.
[0172] A dielectric layer of fluoro-polymer Lisicon D139.RTM. (9%
solids available from Merck Chemicals Ltd.) was spun on top of the
OSC layer on the device and annealed at 70.degree. C. for 8 min to
give a dry dielectric film of approximately 1 .mu.m thick.
[0173] Finally a 40 nm thick gold gate electrode array of
evaporated on top of the dielectric layer in such a way that it
covered the existing source drain electrode structures.
[0174] The initial transfer curve was recorder at bias voltage of
-5 V. Then the device was electrically stressed for 15 h using
source/gate voltage of -40 V and the second transfer curve was
recorded directly after the stress.
[0175] The transfer characteristics are shown in FIG. 5.
Example 1
Top Gate OFET with a Teonex.RTM. Film Covered by a Polynorbornene
Planarization Layer According to the Invention as Substrate
[0176] Teonex Q65FA.RTM. film (available from DuPont Teijin
Films.TM.) was washed in methanol. A layer of the polymer
poly(DMMIBuNB) (hereinafter abbreviated as "pDMMIBuNB"), which is a
homopolymer of the monomer of formula (37), having a molecular
weight M.sub.W=100,000, was formed by depositing a solution of the
polymer (17.5% TS in MAK with added 0.5%
1-chloro-4-propoxy-9H-thioxanthen-9-one w/w) onto the Teonex film
via spin coating (1500 rpm, 30 s) followed by 8 min baking at
70.degree. C. and 4 min UV exposure (UVA 0.011W/cm.sup.2, peak at
365 nm).
[0177] Approximately 60 nm thick gold source drain electrodes were
evaporated onto the polynorbornene layer with a parallel plate
geometry of 20 .mu.m wide by 1 mm long.
[0178] The electrodes were treated with M001 (available from Merck
Chemicals Ltd.) by spin coating from isopropyl alcohol and
evaporating the excess off on a hot plate at 70.degree. C. for 2
min.
[0179] The same OSC Lisicon S1200-Series.RTM. formulation as used
in Comparison Example 1 was then printed as a 5.times.5 cm wide
area block on the array of source/drain electrodes on the film as
described above using a RK Flexiproof 100 flexographic printing
with a 8 cm.sup.3/m.sup.2 loaded anilox and a Cyrel HiQS flexo mat
running at 70 m/min speed. The printed OSC layer was then annealed
at 70.degree. C. for 5 min.
[0180] A dielectric layer of fluoro-polymer Lisicon D139.RTM. (9%
solids available from Merck Chemicals Ltd.) was spun on top of the
OSC layer on the device and annealed at 70.degree. C. for 8 min to
give a dry dielectric film approximately 1 .mu.m thick.
[0181] Finally a 40 nm thick gold gate electrode array is
evaporated on top of the dielectric layer in such a way that it
covered the existing source drain electrode structures.
[0182] The initial transfer curve was recorder at bias voltage of
-5 V. Then the device was electrically stressed for 15 h using
source/gate voltage of -40 V and the second transfer curve was
recorded directly after the stress.
[0183] The transfer characteristics are shown in FIG. 6.
[0184] From FIG. 6 it can be seen that in the OFET device of
Example 1, the layer of pDMMIBuNB on top of Teonex Q65FA.RTM. film
improves stability of the electrical parameters, in comparison to
the OFET device of Comparison Example 1 without the additional
pDMMIBuNB layer (see FIG. 5). Stability of the source-drain current
in the `ON` state (under negative gate bias in case of using p-type
semiconductors) and limited threshold voltage shift after
application of negative gate bias stress (-40 V) are particularly
important to ensure applicability of the transistors.
[0185] Such an improved long term stability of those parameters was
observed for the devices containing the planarization layer of
pDMMIBuNB, compared to devices without the layer of pDMMIBuNB.
[0186] The surface roughness of the substrates of Comparison
Example 1 and Example 1 was measured by Atomic Force Microscopy
(AFM).
[0187] As a result the surface roughness of the Teonex Q65FA.RTM.
substrate as used in Comparison Example 1 is 0.6 nm (Ra) and 20 nm
(Rt), whereas the surface roughness of the same substrate coated
with a layer of pDMMIBuNB as used in Example 1, is 0.2 nm (Ra) and
5 nm (Rt) for pDMMIBuNB layer.
[0188] This shows that the surface roughness was significantly
reduced after application of the planarization layer of
pDMMIBuNB.
[0189] Surface energy measurements using the Owens-Wendt method
were carried out for the substrates of Comparison Example 1 and
Example 1.
[0190] As a result the surface energy of the Teonex Q65FA.RTM.
substrate as used in Comparison Example 1 is 32 mN/m (without
plasma treatment), whereas the surface energy of the same substrate
coated with a layer of pDMMIBuNB as used in Example 1, is 50 mN/m
respectively.
[0191] Since de-wetting may occur at low surface energies<40
mN/m, the substrate of Comparison Example 1 needs further plasma
treatment to increase surface energy. In contrast thereto, a
surface modification of the pDMMIBuNB layer prior to the OSC
deposition, for example in order to improve surface energy and
wetting, is not required. Nevertheless, pDMMIBuNB is resistant to
plasma treatment, which is commonly applied after a
photolithographic process in order to remove post-process
residues.
Comparison Example 2
Top Gate OFET with Melinex.RTM. Film as Substrate
[0192] Melinex ST506.RTM. film (available from DuPont Teijin
Films.TM.) was washed in methanol and treated with argon plasma for
3 min (microwave plasma generator, power: 100 W, argon flow: 500
ml/min) in order to increase surface energy of the substrate.
[0193] Approximately 60 nm thick gold source drain electrodes were
evaporated onto the directly onto the PEN substrate layer with a
parallel plate geometry of 20 .mu.m wide by 1 mm long.
[0194] The electrodes were treated with Lisicon M001.RTM.
(available from Merck Chemicals Ltd.) by spin coating from
isopropyl alcohol and evaporating the excess off on a hot plate at
70.degree. C. for 2 min.
[0195] The same OSC Lisicon S1200-Series.RTM. formulation as used
in Comparison Example 1 was then printed as a 5.times.5 cm wide
area block on the array of source/drain electrodes on the film as
described above using a RK Flexiproof 100 flexographic printing
with a 8 cm.sup.3/m.sup.2 loaded anilox and a Cyrel HiQS flexo mat
running at 70 m/min speed. The printed OSC layer was then annealed
at 70.degree. C. for 5 min.
[0196] A dielectric layer of fluoro-polymer Lisicon D139.RTM. (9%
solids available from Merck Chemicals Ltd.) was spun on top of the
OSC layer on the device and annealed at 70.degree. C. for 8 min to
give a dry dielectric film of approximately 1 .mu.m thick.
[0197] Finally a 40 nm thick gold gate electrode array is
evaporated on top of the dielectric layer in such a way that it
covered the existing source drain electrode structures.
[0198] The initial transfer curve was recorder at bias voltage of
-5 V. Then the device was electrically stressed for 2 h using
source/gate voltage of 30 V and the second transfer curve was
recorded directly after the stress.
[0199] The transfer characteristics are shown in FIG. 7.
Example 2
Top Gate OFET Device with a Melinex.RTM. Film Covered by a
Polynorbornene Planarization Layer According to the Invention as
Substrate
[0200] Melinex ST506.RTM. film (available from DuPont Teijin
Films.TM.) was washed in methanol. A layer of the norbornene
polymer pBuDMMINB (17.5% TS in MAK with added 0.5%
1-chloro-4-propoxy-9H-thioxanthen-9-one w/w) was deposited onto the
Melinex film via spin coating (1500 rpm, 30 s) followed by 8 min
baking at 70.degree. C. and 4 min UV exposure (UVA 0.011W/cm2, peak
at 365 nm).
[0201] Approximately 60 nm thick gold source drain electrodes were
evaporated onto the polynorbornene layer with a parallel plate
geometry of 20 .mu.m wide by 1 mm long.
[0202] The electrodes were treated with Lisicon M001.RTM.
(available from Merck Chemicals Ltd.) by spin coating from
isopropyl alcohol and evaporating the excess off on a hot plate at
70.degree. C. for 2 min.
[0203] The same OSC Lisicon S1200-Series.RTM. formulation as used
in Comparison Example 1 was then printed as a 5.times.5 cm wide
area block on the array of source/drain electrodes on the film as
described above using a RK Flexiproof 100 flexographic printing
with a 8 cm.sup.3/m.sup.2 loaded anilox and a Cyrel HiQS flexo mat
running at 70 m/min speed. The printed OSC layer was then annealed
at 70.degree. C. for 5 min.
[0204] A dielectric layer of fluoro-polymer Lisicon D139.RTM. (9%
solids available from Merck Chemicals Ltd.) was spun on top of the
OSC layer on the device and annealed at 70.degree. C. for 8 min to
give a dry dielectric film of approximately 1 .mu.m thick.
[0205] Finally a 40 nm thick gold gate electrode array is
evaporated on top of the dielectric layer in such a way that it
covered the existing source drain electrode structures.
[0206] The initial transfer curve was recorder at bias voltage of
-5 V. Then the device was electrically stressed for 80 h using
source/gate voltage of 30 V and the second transfer curve was
recorded directly after the stress.
[0207] The transfer characteristics are shown in FIG. 8.
[0208] From FIG. 8 it can be seen that in the OFET device of
Example 2, the layer of pDMMIBuNB on top of Melinex ST506.RTM. film
improves stability of the electrical parameters, in comparison to
the OFET device of Comparison Example 2 without the additional
pDMMIBuNB layer (see FIG. 7). Stability of the source-drain current
in the `ON` state (under negative gate bias in case of using p-type
semiconductors) and limited threshold voltage shift after
application of positive gate bias stress (30V) are particularly
important to ensure applicability of the transistors.
[0209] Such an improved long term stability of those parameters was
observed for the devices containing the planarization layer of
pDMMIBuNB, compared to devices without the layer of pDMMIBuNB.
[0210] The surface roughness of the substrates of Comparison
Example 2 and Example 2 was measured by Atomic Force
Microscope.
[0211] As a result the surface roughness of the Melinex ST506.RTM.
substrate as used in Comparison Example 2 is 0.6 nm (R.sub.a) and
20 nm (R.sub.t), whereas the surface roughness of the same
substrate coated with a layer of pDMMIBuNB as used in Example 2, is
0.2 nm (R.sub.a) and 5 nm (R.sub.t) for pDMMIBuNB layer.
[0212] This shows that the surface roughness was significantly
reduced after application of the planarization layer of
pDMMIBuNB.
[0213] Surface energy measurements using the Owens-Wendt method
were carried out for the substrates of Comparison Example 2 and
Example 2.
[0214] As a result the surface energy of the Melinex ST506.RTM.
substrate as used in Comparison Example 2 is 33 mN/m, whereas the
surface energy of the same substrate coated with a layer of
pDMMIBuNB as used in Example 2, is 50 mN/m respectively.
[0215] Since de-wetting may occur at low surface energies<40
mN/m, the substrate of Comparison Example 2 needs further plasma
treatment to increase surface energy. In contrast thereto, a
surface modification of the pDMMIBuNB layer prior to the OSC
deposition, for example in order to improve surface energy and
wetting, is not required. Nevertheless, pDMMIBuNB is resistant to
plasma treatment, which is commonly applied after a
photolithographic process in order to remove post-process
residues.
[0216] The adhesion of Au gold to the substrates of Comparison
Example 2 and Example 2 was measured by Mecmesin MultiTest 1-i (50
N cell) using 90.degree. peel test. For that purpose both
substrates were covered by approximately 60 nm layers of gold and
25 mm wide tape with 20 N adhesion to gold was applied to peel a
stripe of gold from the substrates.
[0217] As a result the adhesion of gold to the Melinex ST506.RTM.
substrate as used in Comparison Example 2 is less or equal to 0.5N
whereas the adhesion of gold to the same substrate coated with a
layer of pDMMIBuNB as used in Example 2, is 16 N.
Example 3
Top Gate OFET Device with a Melinex.RTM. Film Covered by a
Polynorbornene Planarization Layer According to the Invention as
Substrate
[0218] Melinex ST506.RTM. film (available from DuPont Teijin
Films.TM.) was washed in methanol. A layer of the norbornene
polymer poly(DMMIBuNB/TESNB) which is a co-polymer of the monomer
DMMIBuNB of the formula (37) and the monomer TESNB of the formula
(53) in the ratio: 9:1, dissolved in MAK to the concentration of
17.5% TS) was deposited onto the Melinex film via spin coating
(1500 rpm, 30 s) followed by 8 min baking at 70.degree. C. and 5
min UV exposure (UVA 0.011W/cm.sup.2, peak at 365 nm).
[0219] Approximately 60 nm thick gold source drain electrodes were
evaporated onto the polynorbornene layer with a parallel plate
geometry of 20 .mu.m wide by 1 mm long.
[0220] The electrodes were treated with Lisicon M001.RTM.
(available from Merck Chemicals Ltd.) by spin coating from
isopropyl alcohol and evaporating the excess off on a hot plate at
70.degree. C. for 2 min.
[0221] The same OSC Lisicon S1200-Series.RTM. formulation as used
in Comparison Example 1 was then printed as a 5.times.5 cm wide
area block on the array of source/drain electrodes on the film as
described above using a RK Flexiproof 100 flexographic printing
with a 8 cm.sup.3/m.sup.2 loaded anilox and a Cyrel HiQS flexo mat
running at 70 m/min speed. The printed OSC layer was then annealed
at 70.degree. C. for 5 min.
[0222] A dielectric layer of fluoro-polymer Lisicon D139.RTM. (9%
solids available from Merck Chemicals Ltd.) was spun on top of the
OSC layer on the device and annealed at 70.degree. C. for 8 min to
give a dry dielectric film of approximately 1 .mu.m thick.
[0223] Finally a 40 nm thick gold gate electrode array is
evaporated on top of the dielectric layer in such a way that it
covered the existing source drain electrode structures.
[0224] The initial transfer curve was recorder at bias voltage of
-5 V. Then the device was electrically stressed for 80 h using
source/gate voltage of 30 V and the second transfer curve was
recorded directly after the stress.
[0225] The transfer characteristics are shown in FIG. 9.
[0226] From FIG. 9 it can be seen that in the OFET device of
Example 3, the layer of poly(DMMIBuNB/TESNB) on top of Melinex
ST506.RTM. film improves stability of the electrical parameters, in
comparison to the OFET device of Comparison Example 3 without the
additional poly(DMMIBuNB/TESNB) layer (see FIG. 7). Stability of
the source-drain current in the `ON` state (under negative gate
bias in case of using p-type semiconductors) and limited threshold
voltage shift after application of positive gate bias stress (30V)
are particularly important to ensure applicability of the
transistors.
[0227] Such an improved long term stability of those parameters was
observed for the devices containing the planarization layer of
poly(DMMIBuNB/TESNB), compared to devices without the layer of
poly(DMMIBuNB/TESNB).
[0228] Furthermore, the OFET device of Example 3 shows a decreased
source-drain current in the `OFF` state (under positive gate bias
in case of using p-type semiconductors) by over one order of
magnitude for non-patterned OSC layer (where OSC layer covers the
whole area of a substrate and there is significant current leakage
between the neighbouring devices through the OSC layer).
[0229] The surface roughness of the substrates of Comparison
Example 2 and Example 3 was measured by Atomic Force
Microscopy.
[0230] As a result the surface roughness of the Melinex ST506.RTM.
substrate as used in Comparison Example 2 (without plasma
treatment) is 0.6 nm (R.sub.a) and 20 nm (R.sub.t), whereas the
surface roughness of the same substrate coated with a layer of
poly(DMMIBuNB/TESNB) as used in Example 3, is 0.2 nm (R.sub.a) and
5 nm (R.sub.t) for poly(DMMIBuNB/TESNB) layer.
[0231] This shows that the surface roughness was significantly
reduced after application of the planarization layer of
poly(DMMIBuNB/TESNB).
[0232] Surface energy measurements using the Owens-Wendt method
were carried out for the substrates of Comparison Example 2 and
Example 3.
[0233] As a result the surface energy of the Melinex ST506.RTM.
substrate as used in Comparison Example 2 is 33 mN/m, whereas the
surface energy of the same substrate coated with a layer of
poly(DMMIBuNB/TESNB) as used in Example 3, is 51 mN/m
respectively.
[0234] Since de-wetting may occur at low surface energies<40
mN/m, the substrate of Comparison Example 2 needs further plasma
treatment to increase surface energy. In contrast thereto, a
surface modification of the poly(DMMIBuNB/TESNB) layer prior to the
OSC deposition, for example in order to improve surface energy and
wetting, is not required. Nevertheless, poly(DMMIBuNB/TESNB) is
resistant to plasma treatment, which is commonly applied after a
photolithographic process in order to remove post-process
residues.
[0235] The adhesion of Au gold to the substrates of Comparison
Example 2 and Example 3 was measured by Mecmesin MultiTest 1-i (50
N cell) using 90.degree. peel test. For that purpose both
substrates were covered by approximately 60 nm layers of gold and
25 mm wide tape with 20 N adhesion to gold was applied to peel a
stripe of gold from the substrates.
[0236] As a result the adhesion of gold to the Melinex ST506.RTM.
substrate as used in Comparison Example 2 is less or equal to 0.5N,
whereas the adhesion of gold to the same substrate coated with a
layer of poly(DMMIBuNB/TESNB) as used in Example 2, is >20
N.
[0237] The results of Example 1, 2 and 3 demonstrate that a
substrate coated with a polynorbornene planarization layer provides
largely improved stability of OFETs compared to a prior art
substrate as used in Comparison Example 2, which is considered as a
benchmark. Low surface roughness and high surface energy of
polynorbornene layers are also beneficial for simplification of the
OFET manufacturing process. Additionally, specific substituents, on
the polynorbornene backbone, like triethoxysilyl (TES) as in
formula (53), provide large increase of adhesion to metals like
gold, which eliminate the need for additional adhesion layers
between the planarization materials and the electrodes.
[0238] All the references described above are incorporated by
reference into this application.
* * * * *