U.S. patent application number 11/075144 was filed with the patent office on 2008-06-05 for silylethynylated heteroacenes and electronic devices made therewith.
Invention is credited to John E. Anthony, Susan A. Odom, Sean Richard Parkin, Marcia M. Payne.
Application Number | 20080128680 11/075144 |
Document ID | / |
Family ID | 39474657 |
Filed Date | 2008-06-05 |
United States Patent
Application |
20080128680 |
Kind Code |
A1 |
Anthony; John E. ; et
al. |
June 5, 2008 |
SILYLETHYNYLATED HETEROACENES AND ELECTRONIC DEVICES MADE
THEREWITH
Abstract
Novel silylethynylated heteroacenes and electronic devices made
with those compounds are disclosed.
Inventors: |
Anthony; John E.;
(Lexington, KY) ; Payne; Marcia M.; (Evanston,
IL) ; Odom; Susan A.; (Atlanta, GA) ; Parkin;
Sean Richard; (Lexington, KY) |
Correspondence
Address: |
KING & SCHICKLI, PLLC
247 NORTH BROADWAY
LEXINGTON
KY
40507
US
|
Family ID: |
39474657 |
Appl. No.: |
11/075144 |
Filed: |
March 8, 2005 |
Current U.S.
Class: |
257/40 |
Current CPC
Class: |
H01L 51/0074 20130101;
H01L 51/0094 20130101; H01L 51/0545 20130101; Y02E 10/549 20130101;
C07F 7/0812 20130101 |
Class at
Publication: |
257/40 |
International
Class: |
H01L 29/08 20060101
H01L029/08; H01L 35/24 20060101 H01L035/24; H01L 51/00 20060101
H01L051/00 |
Goverment Interests
[0001] This invention was made with support from the Office of
Naval Research and by the Defense Advanced Research Projects Agency
under Grant No. N00014-02-1-0033. The government may have certain
rights in this invention.
Claims
1. A compound of the formula: ##STR00008## ##STR00009## wherein
R=an alkyl, perfluoroalkyl, aryl, alkoxy or trialkylsilyl,
R.sup.1=halogen and X=--O, --S, --Se or --NH.
2. A compound, comprising: a mixture of stereoisomers with the
following formulae: ##STR00010## wherein R=an alkyl,
perfluoroalkyl, aryl, alkoxy or trialkylsilyl, R.sup.1=halogen and
X=--O, --S, --Se or --NH.
3. A compound of the formula: ##STR00011## wherein R=an alkyl,
perfluoroalkyl, aryl, alkoxy or trialkylsilyl, R.sup.1=halogen and
X=--O, --S, --Se or --NH.
4. A compound of the formula: ##STR00012## wherein R=an alkyl,
perfluoroalkyl, aryl, alkoxy or trialkylsilyl, R.sup.1=halogen and
X=--O, --S, --Se or --NH.
5. A compound, comprising: a mixture of isomers with the following
formulae: ##STR00013## wherein R=an alkyl, perfluoroalkyl, aryl,
alkoxy or trialkylsilyl, R.sup.1=hydrogen, alkyl, aryl,
perfluoroalkyl, alkoxy, halogen and X=--O, --S, --Se or --NH.
6. A compound, comprising: a mixture of isomers ##STR00014##
wherein R=an alkyl, perfluoroalkyl, aryl, alkoxy or trialkylsilyl,
R.sup.1=hydrogen, alkyl, aryl, perfluoroalkyl, alkoxy, halogen and
X=--O, --S, --Se or --NH.
7. A compound, comprising: a mixture of isomers ##STR00015##
wherein R=an alkyl, perfluoroalkyl, aryl, alkoxy or trialkylsilyl,
R.sup.1=hydrogen, alkyl, aryl, perfluoroalkyl, alkoxy, halogen and
X=--O, --S, --Se or --NH.
8. A compound, comprising: a mixture of isomers with the following
formulae: ##STR00016## wherein R=an alkyl, perfluoroalkyl, aryl,
alkoxy or trialkylsilyl, R.sup.1=hydrogen, alkyl, aryl,
perfluoroalkyl, alkoxy, halogen and X=--O, --S, --Se or --NH.
9. A compound, comprising: a mixture of isomers ##STR00017##
wherein R=an alkyl, perfluoroalkyl, aryl, alkoxy or trialkylsilyl,
R.sup.1=hydrogen, alkyl, aryl, perfluoroalkyl, alkoxy, halogen and
X=--O, --S, --Se or --NH.
10. A compound, comprising: a mixture of isomers ##STR00018##
wherein R=an alkyl, perfluoroalkyl, aryl, alkoxy or trialkylsilyl,
R.sup.1=hydrogen, alkyl, aryl, perfluoroalkyl, alkoxy, halogen and
X=--O, --S, --Se or --NH.
11. A transistor, comprising: a gate electrode; a semiconductor
constructed from at least one material selected from a group
consisting of ##STR00019## ##STR00020## wherein R=an alkyl,
perfluoroalkyl, aryl, alkoxy or trialkylsilyl, R.sup.1=halogen and
X=--O, --S, --Se or --NH; an insulator between said gate electrode
and said semiconductor; a source electrode; and a drain
electrode.
12. A transistor, comprising: a gate electrode; a semiconductor
constructed from at least one material selected from a group
consisting of ##STR00021## wherein R=an alkyl, perfluoroalkyl,
aryl, alkoxy or trialkylsilyl, R.sup.1=halogen and X=--O, --S, --Se
or --NH; an insulator between said gate electrode and said
semiconductor: a source electrode; and a drain electrode.
13. A transistor, comprising: a gate electrode; a semiconductor
constructed from at least one material selected from a group
consisting of ##STR00022## wherein R=an alkyl, perfluoroalkyl,
aryl, alkoxy or trialkylsilyl, R.sup.1=halogen and X=--O, --S, --Se
or --NH. an insulator between said gate electrode and said
semiconductor; a source electrode; and a drain electrode.
14. A transistor, comprising: a gate electrode; a semiconductor
constructed from at least one material selected from a group
consisting of ##STR00023## wherein R=an alkyl, perfluoroalkyl,
aryl, alkoxy or trialkylsilyl, R.sup.1=hydrogen, alkyl, aryl,
perfluoroalkyl, alkoxy, halogen and X=--O, --S, --Se or --NH; an
insulator between said gate electrode and said semiconductor; a
source electrode; and a drain electrode.
15. A photovoltaic apparatus, comprising: a transparent anode; a
semiconductor constructed from at least one material selected from
a group consisting of ##STR00024## ##STR00025## wherein R=an alkyl,
perfluoroalkyl, aryl, alkoxy or trialkylsilyl, R.sup.1=hydrogen,
alkyl, aryl, perfluoroalkyl, alkoxy, halogen and X=--O, --S, --Se
or --NH; an n-type material; and a cathode.
16. A photovoltaic apparatus, comprising: a transparent anode; a
semiconductor constructed from at least one material selected from
a group consisting of ##STR00026## wherein R=an alkyl,
perfluoroalkyl, aryl, alkoxy or trialkylsilyl, R.sup.1=hydrogen,
alkyl, aryl, perfluoroalkyl, alkoxy, halogen and X=--O, --S, --Se
or --NH; an n-type material; and a cathode.
17. A photovoltaic apparatus, comprising: a transparent anode; a
semiconductor constructed from at least one material selected from
a group consisting of ##STR00027## wherein R=an alkyl,
perfluoroalkyl, aryl, alkoxy or trialkylsilyl, R.sup.1=hydrogen,
alkyl, aryl, perfluoroalkyl, alkoxy, halogen and X=--O, --S, --Se
or --NH; an n-type material; and a cathode.
18. A photovoltaic apparatus, comprising: a transparent anode; a
semiconductor constructed from at least one material selected from
a group consisting of ##STR00028## wherein R=an alkyl,
perfluoroalkyl, aryl, alkoxy or trialkylsilyl, R.sup.1=hydrogen,
alkyl, aryl, perfluoroalkyl, alkoxy, halogen and X=--O, --S, --Se
or --NH; an n-type material; and a cathode.
Description
TECHNICAL FIELD
[0002] The present invention relates generally to the field of
organic semiconductors and, more particularly, to silylethynylated
heteroacenes as well as to electronic devices made with these
compounds.
BACKGROUND OF THE INVENTION
[0003] Display technology is expected to become a dominant sector
of high-tech industry in the future. It is also expected that the
flat panel display technology will be revolutionized by the use of
organic semiconductors that will allow manufacture of cheap,
flexible, lightweight, fully portable flat panel displays with no
apparent limits to their size. It is predicted that due to the
lower manufacturing cost, organic semiconductor based displays will
eventually gain dominance over amorphous silicon based counterparts
and the respective market share will grow to $1.6 billion by 2007.
To realize these goals, however, significant breakthroughs will
have to take place in the area of organic semiconductor material
and device processing.
[0004] Interest in organic thin film transistors (OTFTs) for
possible use in displays, sensors and other large area electronic
applications has been increasing rapidly. Best reported organic
thin film transistor (OTFT) device performance rivals or exceeds
that of hydrogenated amorphous silicon devices, and low OTFT
process temperatures allow fabrication on a range of surfaces
including cloth, paper or lower temperature polymeric
substrates.
[0005] Organic semiconductors for use in OTFTs can be broadly
divided into two groups as high and low mobility materials. High
mobility materials have mobility >0.1 cm.sup.2/V-s, usefully
large carrier energy bandwidth (>0.1 eV) and weak or sometimes
absent temperature activation of mobility. To date, most high
mobility organic semiconductors have been small molecule materials
(with pentacene the most notable example) and most have been
deposited by vacuum sublimation or from a solution precursor with a
high-temperature (>150.degree. C.) conversion step. Low mobility
materials have mobility from about 10.sup.-5-10.sup.-1
cm.sup.2/V-s, typically transport carriers by hopping, and have
strong temperature activation of mobility. Most polymeric organic
semiconductors fall into this group and many have the potential
advantage that they can be deposited from solution.
[0006] To date, there have been few reports of low-temperature
solution processed organic semiconductors with high mobility. In
addition, even for low mobility materials, current solution
deposition techniques have not demonstrated material structure,
thickness and property control comparable to vacuum deposition
techniques. The present invention relates to new organic
semiconductor compounds with relatively low OTFT process
temperatures and relatively high mobility.
SUMMARY OF THE INVENTION
[0007] The present invention relates to novel silylethynylated
heteroacenes (anthra(diheterocycles), tetra(diheterocycles) and
penta(diheterocycles) compounds) as well as to transistors and
photovoltaic apparatus made from those compounds. The novel
compounds comprise the following formula:
##STR00001## ##STR00002##
wherein R=an alkyl having C.sub.1-C.sub.8, perfluoroalkyl having
C.sub.1-C.sub.8, aryl, alkoxy or trialkylsilyl, R.sup.1=hydrogen,
alkyl having C.sub.1-C.sub.8, aryl, perfluoroalkyl having
C.sub.1-C.sub.8, alkoxy, halogen and x=--O, --S, --Se or --NH.
[0008] In accordance with yet another aspect of the present
invention a transistor is constructed from the novel compounds of
the present invention. The transistor comprises a gate electrode, a
semiconductor constructed from the novel compound of the present
invention, an insulator between the gate electrode and the
semiconductor, a source electrode and a drain electrode.
[0009] In accordance with yet another aspect of the present
invention, a photovoltaic apparatus is provided. That photovoltaic
apparatus comprises a transparent anode, a semiconductor
constructed from a novel compound of the present invention, an
n-type material and a cathode.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
[0010] The accompanying drawing incorporated in and forming a part
of the specification, illustrates several aspects of the present
invention and together with the description serves to explain
certain principles of the invention. In the drawing:
[0011] FIGS. 1a and 1b are schematical illustrations of two
possible embodiments for the field-effect transistor of the present
invention; and
[0012] FIGS. 2a and 2b are schematical representations illustrating
two possible embodiments of the photovoltaic apparatus of the
present invention.
[0013] Reference will now be made in detail to the present
preferred embodiments of the invention as illustrated in the
accompanying drawing figures.
DETAILED DESCRIPTION OF THE INVENTION
[0014] The novel compounds of the present invention may be broadly
described as silylethynylated heteroacenes. The compounds have the
following structural formulae:
##STR00003## ##STR00004##
[0015] The silylethynylated heteroacenes are prepared as a mixture
of isomers. [0016] Formulae A.sub.1 and A.sub.2 represent the two
isomers of anthra (diheterocylces). [0017] Formulae B.sub.1 and
B.sub.2 represent the two isomers of tetra (diheterocyles). [0018]
Formulae C.sub.1 and C.sub.2 represent the two isomers of penta
(diheterocyles). [0019] The novel compounds of the present
invention include both the mixture of the isomers of Formulae
A.sub.1, A.sub.2; B.sub.1, B.sub.2; or C.sub.1, C.sub.2 and the
pure isomers A.sub.1, A.sub.2, B.sub.1, B.sub.2, C.sub.1, or
C.sub.2.
[0020] The isomers A.sub.1, A.sub.2, B.sub.1, B.sub.2, C.sub.1, or
C.sub.2 may be purified from the mixture of isomers of Formulae
A.sub.1, A.sub.2; B.sub.1, B.sub.2; or C.sub.1, C.sub.2 by methods
known to those skilled in the art including but not limited to
high-performance liquid chromatography (HPLC).
[0021] The novel compounds of the present invention are prepared by
a relatively simple and straightforward method. Specifically, the
silylethynylated heteroacenes are easily made by the addition of an
alkynyllithium to the corresponding acenequinone, followed by
reductive workup with either HI or tin (II) chloride:
##STR00005##
[0022] This type of reaction is well-described in:
[0023] Miller, G. P.; Mack, J.; Briggs, J. Org. Lett. 2000, 2,
3983.
[0024] Anthony, J. E.; Eaton, D. L.; Parkin, S. R. Org. Lett. 2002,
4, 15.
[0025] Anthony, J. E.; Brooks, J. S.; Eaton, D. L.; Parkin, S. J.
Am. Chem. Soc. 2001, 123, 9482.
[0026] Payne, M. M.; Odom, S. A.; Parkin, S. R.; Anthony, J. E.
Org. Lett. 2004 6, 3325.
[0027] The acenequinone is very easily prepared by a 4-fold aldol
condensation between a dialdehyde and commercially-available
1,4-cyclohexanedione:
##STR00006##
[0028] This condensation is well-described in:
[0029] De la Cruz, P.; Martin, N.; Miguel, F.; Seoane, C.; Albert,
A.; Cano, H.; Gonzalez, A.; Pingarron, J. M. J. Org. Chem. 1992,
57, 6192.
[0030] The "R" group of these dialdehydes is typically installed by
the following sequence:
##STR00007##
[0031] This procedure is described for thiophene dialdehyde in
detail in: Laquindanum, J. G.; Katz, H. E.; Lovinger, A. J. J. Am.
Chem. Soc. 1998, 120, 664.
[0032] Thus the "base unit" for all of these materials is the
heterocyclic dialdehyde. Many of these are known in the literature,
and some are even commercially available:
[0033] Thiophene 2,3-dialdehyde: Commercially available from
Aldrich and Acros chemical
[0034] Furan 2,3-dialdehyde: Prepared as in Zaluski, M. C.; Robba,
M.; Bonhomme, M. Bull. Chim. Soc. Fr. 1970, 4, 1445.
[0035] Selenophene 2,3-dialdehyde: Prepared as in Paulmier, C.;
Morel, J.; Pastour, P.; Semard, D. Bull. Chim. Soc. Fr. 1969, 7,
2511.
[0036] Thiazole dialdehyde: Prepared as in Robba, M.; Le Guen, Y.
Bull Chim. Soc. Fr. 1969, 11, 4026.
[0037] Imidazole dialdehyde: Prepared as in Kolks, G.; Frihart, C.
R.; Coughlin, P. K.; Lippard, S. J. Inorg. Chem. 1981, 20, 2933
[0038] Other heterocyclic dialdehydes can be prepared by the same
methods outlined for the synthesis of the furan and selenophene
compounds. [0039] The following synthesis and examples are prepared
to further illustrate the invention, but it is not to be considered
as limited thereto.
EXAMPLE 1
[0040] 5,11-Bis(triethylsilylethynyl)anthra
[2,3-b:6,7-b']dithiophene and 5,11-Bis(triethylsilylethynyl)anthra
[2,3-b:7,6-b']dithiophene. To an oven-dried 250-mL round-bottom
flask equipped with a stir bar and cooled under N.sub.2 was added
hexanes (20 mL) and 0.38 mL of triethylsilyl acetylene (2.0 mmol),
followed by the dropwise addition of 0.73 mL of n-BuLi (1.8 mmol,
2.46 M solution in hexanes). This mixture was stirred for 1 h, then
hexanes (80 mL) and anthradithiophenequinone (prepared by method
described in De la Cruz, P. et al. J. Org. Chem. 1992, 57, 6192.)
(0.16 g, 0.34 mmol) were added. The mixture was heated at
60.degree. C. overnight, then quenched with 0.5 mL of water.
SnCl.sub.2.2H.sub.2O (0.50 g, 2.2 mmol) in 10% aq. HCl (1 mL) was
added and the mixture was stirred for 2 h at 60.degree. C. The
solution was dried over MgSO.sub.4, then loaded onto a thick pad of
silica. The silica was rinsed with hexanes (500 mL), then the
product was eluted using hexanes:DCM (5:1). Removal of solvent
yielded 0.18 g (0.31 mmol, 91%) of a reddish powder.
Recrystallization from hexanes yielded thick dark-red plates.
Recrystallized 3.times. from hexanes. Yield: 91%. MP: 151.degree.
C. .sup.1H-NMR (400 MHz, CDCl.sub.3) .delta.=9.18 (s,2H), 9.13 (s,
2H), 7.57 (d, J=5.6 Hz, 2H, syn isomer), 7.57 (d, J=5.2 Hz, 2H,
anti isomer), 7.47 (d, J=5.6 Hz, 2H), 1.27 (tt, J=8.0 Hz, 1.6 Hz,
18H), 0.94 (q, J=8.0 Hz, 12H). .sup.13C-NMR (400 MHz, CDCl.sub.3)
.delta.=140.27, 140.18, 139.82, 139.68, 133.70, 130.11 (2C), 130.01
(2C), 129.92 (2C), 129.81, 129.17, 123.95, 121.50, 121.44, 120.20,
118.05, 117.69,8.04 (2C), 7.82, 4.93 (2C), 4.50. Anal. calcd % C:
72.02, % H: 6.75. Found % C: 71.68, % H: 6.75.
[0041] For preparation of systems with alternative "R" groups, a
different acetylene would be substituted for triethylsilyl
acetylene in the above preparation. For preparation of systems
where "R'" is different from "H" the requisite precursor quinones
can be prepared as in (Laquindanum, J. G. et al., J. Am. Chem. Soc.
1998, 120, 664.)
EXAMPLE 2
[0042] Tetra[2,3-b:8,9-b']dithiophene-5,13-dione and
Tetra[2,3-b:9,8-b']dithiophene-5,13-dione. A 1:2 mixture of
2,3-thiophenedicarboxaldehyde (0.85 g, 6.07 mmol) and
benzo[1,2-b]thiophene-4,5-dicarboxaldehyde (1.66 g, 8.70 mmol) was
dissolved in THF (200 mL) in a 500-mL round-bottom flask with a
stir bar, then 1,4-cyclohexanedione (0.83 g, 7.40 mmol) was added
and the solution was stirred until uniform. After the addition of
15% KOH (2 mL), precipitate began to form immediately, and vigorous
stirring was continued overnight. The solution was filtered to
yield 3.87 g of a light brown powder made up of insoluble quinones
which were used directly in the next step: MS (70 eV, EI) m/z 370
(100%, M+).
[0043] 5,13-Bis(tris(trimethylsilyl)silylethynyl)tetra
[2,3-b:8,9-b']dithiophene and
5,13-Bis(tris(trimethylsilyl)silylethynyl)tetra[2,3-b:9,8-b']dithiophene.
To an oven-dried 500-mL round-bottom flask cooled under N.sub.2 and
equipped with a stir bar was added hexanes (150 mL) and
tris((trimethylsilyl)silyl acetylene (14 g, 51.1 mmol).
n-BuLi.(19.5 mL, 0.47, 9 mmol, 2.6 M in hexanes) was added dropwise
and the mixture was stirred for 2 hr. The above quinone mixture
(3.87 g) was added and stirring was continued overnight, followed
by the addition of anhydrous THF (20 mL) and additional stirring
for 2 d. Water (2 mL) and a solution of SnCl.sub.2.H.sub.20 (10.0
g, 44 mmol) in 10% HCl (20 mL) was added and the solution was
stirred for 2 hr. DCM (100 mL) was then added and the organic layer
was separated, dried over MgSO.sub.4, and rinsed through a thin pad
of silica (DCM). Solvent was concentrated to a volume of 10 mL,
then diluted with hexanes (200 mL), and rinsed onto a thick pad of
silica. The silica was rinsed with hexanes (600 mL), then
hexanes:DCM (1:1) to elute the product mixture, and solvent was
removed from this second fraction. Using column chromatography
(hexanes:ethyl acetate (9:1)), 0.82 g of the desired
tetradithiophene were isolated. The tetradithiophene was
recrystallized from acetone to yield dark-blue needles. .sup.1H-NMR
(400 MHz, CDCl.sub.3) .delta.=9.53 (s, 1H), 9.45 (s, 1H), 9.16 (s,
1H), 9.13 (s, 1H), 8.53 (s, 1H), 8.49 (s, 1H), 7.54 (d, J=5.6 Hz,
1H), 7.50 (d, J=6.2 Hz, 1H), 7.41 (s, 1H), 7.40 (s, 1H), 1.08 (s,
54H). .sup.13C-NMR (400 MHz, CDCl.sup.3) .delta.=140.49,140.46,
140.20, 140.19, 139.92, 139.86,138.98,138.90, 130.27, 129.74,
129.61, 126.84,125.35,124.02,123.72,122.34,122.29,121.64, 121.04,
120.99, 120.29, 107.05, 106.72, 105.64, 104.85, 104.76, 11.5.
UV-VIS (DCM): .lamda..sub.abs (.epsilon.): 244 (18700), 300
(32400), 328 (61800), 372 (6940), 392 (5610), 465 (2110),528 (766),
555 (1340), 599 (2810), 653 (4960). IR (KBr) .upsilon..sub.max
(cm.sup.-1): 2956 (m), 2945 (m), 2860 (s), 2129 (m), 1460 (m), 1400
(m), 1366 (s), 1061 (m), 997 (w), 882 (s),752 (s), 720 (vs), 661
(s), 586 (m).
EXAMPLE 3
[0044] Penta[2,3-b:9,10-b']dithiophene-6,14-dione and
Penta[2,3-b:10,9-b']dithiophene-6,14-dione. In a 500-mL
round-bottom flask equipped with a stir bar,
benzo[1,2-b]thiophene-4,5-dicarboxaldehyde (2.35 g, 12.4 mmol) was
dissolved in THF (200 mL). 1,4-Cyclohexanedione (0.70 g, 6.2 mmol)
was added and stirred until the solution was uniform, then 15% KOH
(2 mL) was added. Vigorous stirring was continued overnight, then
the solution was filtered and rinsed with ether (20 mL) and DCM (20
mL). The brown solid was heated to reflux in DMF (400 mL) for 2 hr,
then cooled and filtered to yield 1.6 g (3.8 mmol) of the desired
quinone as a light brown insoluble powder. MS (70 eV, EI) m/z 420
(42%, M.sup.+).
[0045] 6,14- Bis(tri(t-butyl)silylethynyl)-penta
[2,3-b:9,10-b']dithiophene and 6,14-Bis(tri(t-
butyl)silylethynyl)-penta [2,3-b:10,9-b']dithiophene (6b). To an
oven-dried 250-mL round-bottom flask equipped with a stir bar and
cooled under N.sub.2 was added anhydrous THF (40 mL) and
tri(t-butyl)silyl acetylene (3.59 g, 16.0 mmol). n-BuLi (5.7 mL, 14
mmol, 2.6 M in hexanes) was added dropwise and the solution was
stirred for 1 hr, then the abovementioned quinone (1.6 g, 3.8 mmol)
was added. After stirring for 24 hr, additional anhydrous THF (40
mL) was added and stirring was continued for 3 days. Water (2 mL)
and a solution of SnCl.sub.2.H.sub.2O (1.0 g, 4.4 mmol) in 10% HCl
(2 mL) was added and the solution was stirred for 2 hr. DCM (200
mL) was added and the organic layer was separated, dried over
MgSO.sub.4, and rinsed through a thin pad of silica (DCM). Solvent
was concentrated to a volume of 10 mL then diluted with hexanes
(200 mL). This solution was poured onto a thick pad of silica and
rinsed with hexanes (500 mL), then hexanes:DCM (1:1) to elute the
product. Removal of solvent yielded 0.44 g (0.53 mmol, 14%) of
product as a sparingly-soluble green powder. Recrystallization from
toluene, then from CS.sub.2 yielded 6b as slender dark green
needles. .sup.1H-NMR (400 MHz, CDCl.sub.3) .delta.=9.49 (s, 2H),
9.41 (s, 2H), 8.41 (s, 2H), 8.38 (s, 2H), 7.46 (d, J=5.6 Hz, 2H),
7.36 (s, J=5.6 Hz, 2H), 1.50 (s, 54H). .sup.13C-NMR (400 MHz,
CS.sup.2/C.sub.6D.sub.6) .delta.=140.52, 138.91, 130.98, 130.86,
130.67, 130.55, 129.57, 128.92, 128.88, 128.78, 128.75, 128.26,
127.96,127.94,127.59,126.11,124.08,122.94, 121.61, 109.10,
106.70,97.94,31.12, 30.81,28.89,22.73. UV-VIS (DCM):
.lamda..sub.abs (.epsilon.): 277 (42500), 342 (69500), 373 (6350),
398 (2770),416 (2740),441 (2220),475 (1730),577 (145),623 (474),690
(1170),762 (2600). 1R (KBr) .upsilon..sub.max (cm.sup.-1): (cmol):
3400 (w), 2972 (m), 2935 (m), 2859 (5), 2133 (5), 1648 (w), 1385
(s), 1115 (m), 1032 (w), 890 (s), 820 (s), 748 (s), 619 (s). Anal
calcd for C.sub.54H.sub.66S.sub.2Si.sub.2.H.sub.2O % C: 75.99, % H:
8.03. Found % C: 75.61, % H: 7.93. MS (70 eV, EI) m/z 834 (100%,
M.sup.+), 777 (63%, M.sup.+-C.sub.4H.sub.9). MP: 268.degree. C.
(dec.).
[0046] The compounds of the present invention demonstrate
remarkable physical and electronic properties. The silyl acetylene
unit substituted on the inner aromatic ring serves two important
purposes. First it lends solubility to the molecule, allowing
processing by simple, solution-based methods. Secondly and perhaps
more importantly, this functional group causes the molecules to
self-assemble into .pi.-stacked arrays that are critical to
improved device performance. More specifically, this molecular
arrangement leads to improved conductivity, reduced band gap and
field effect transistors (FETs) devices with a hole mobility of
0.001 to 1.0 cm.sup.2/Vs.
[0047] A number of useful electronic devices may be constructed
from the novel compounds of the present invention. As illustrated
in FIG. 1a a field effect transistor (FET) 10 is comprised of a
gate electrode 12 of a type known in the art, an insulator or gate
dielectric 14 also of a type known in the art and a semiconductor
16 in the form of a thin layer or film of the compounds of the
present invention. In addition, the FET 10 includes a conductive
source electrode 18 and a drain electrode 20 both operatively
connected to the semiconductor 16.
[0048] The insulator 14 may, for example, be a dielectric or metal
oxide or even an insulating polymer like poly(methylmethacrylate).
The conducting source and drain electrodes 18, 20 may be metals
known in the art to be useful as electrodes, heavily doped
semiconductors such as silicon or even a conducting polymer.
[0049] The FET illustrated in FIG. 1a is known as a top-contact
configuration. An alternative embodiment of the FET 10 of the
present invention is illustrated in FIG. 1b. This configuration is
known as a bottom-contact configuration. The gate electrode 12,
source electrode 18 and drain electrode 20 may again be any sort of
conductor: gold, silver, aluminum, platinum, heavily-doped silicon
or an organic conducting polymer. The insulator or gate dielectric
14 can be an oxide such as aluminum oxide or silicone oxide or an
insulating polymer such as poly(methylmethacrylate). In either
configuration the compound of the present invention may be applied
either by solution or vapor methods to form the semiconductor
16.
EXAMPLE 4
[0050] The substrate for the field-effect transistors consisted of
a heavily-doped Si wafer with thermally grown oxide layer (370 nm),
serving as gate electrode and dielectric. Gold source and drain
contacts were evaporated to yield devices with channel length of 22
.mu.m and channel width of 340 .mu.m. The gold electrodes were then
treated with pentafluorobenzenethiol to improve the electrode
interface. A 1-2 wt % solution of the triethylsilyl
anthradithiophene derivative of Example 1 in toluene was spread
across the device surface using a plastic blade, and the solvent
allowed to evaporate. The devices were then heated in air at
90.degree. C. for two minutes to drive off residual solvent.
[0051] The triethylsilyl anthradithiophene derivative of Example 1
formed a uniform film of excellent quality yielding hole mobility
of 1.0 cm.sup.2/Vs with excellent on/off current ratio (10.sup.7).
The performance of this material is likely due to the close
.pi.-stacked interactions in the crystal. The triethylsilyl
anthradithiophene derivative adopts a 2-D .pi.-stacking arrangement
with a .pi.-face separation of approximately 3.25 .ANG.. The
triethylsilyl anthradithiophene derivative was also characterized
by a .pi.-overlap of 1.57 .ANG..sup.2 and a lateral slip of 2.75,
1.76 .ANG.. All measurements were performed in air at room
temperature and the mobility was calculated from the saturation
currents.
[0052] A photovoltaic apparatus 22 is illustrated in FIG. 2a. The
photovoltaic apparatus 22 comprises a transparent conductive
electrode or anode 24, a semiconductor 26 in the form of a thin
layer or film of the compound of the present invention and a bottom
electrode or cathode 28.
[0053] In the photovoltaic apparatus embodiment illustrated in FIG.
2a, a layer 30 of n-type material is provided between the
semiconductor 26 and the cathode 28. In the photovoltaic apparatus
22 illustrated in FIG. 2b the semiconductor 26 comprises the
compound of the present invention blended with an n-type
material.
[0054] In the case of organic solar cells, the compounds of the
present invention are typically used as the hole transporter (the
"p-type" material). This material must be used in conjunction with
an n-type material, defined as any electron-accepting compound
(examples: C60 or solubilized derivatives PTCBI, other perylene
diimides).
[0055] The photovoltaic apparatus 22 can typically be constructed
in the two ways illustrated in FIGS. 2a and 2b. As illustrated in
FIG. 2a, the p-type compound and the n-type compound are both
deposited from vapor or solution in sequential steps, leading to a
single heterojunction interface. Alternatively, as illustrated in
FIG. 2b, the p-type material and the n-type material may be mixed
and deposited from solution on the anode prior to deposition of the
cathode material. In this embodiment the p-type and n-type
materials phase segregate, leading to multiple heterojunctions in
the bulk. In both cases the anode material typically has a high
work function and is transparent (ITO or 10 oxide on glass or
plastic). In contrast, the cathode 28 is a low work function
conductor, and is typically reflective to improve efficiency
(aluminum, silver or an indium-gallium eutectic). In either case
the anode layer can be pre-coated with a commercial conducting
polymer PEDOT in order to improve charge injection efficiency.
* * * * *