WO2009052215A1

WO2009052215A1 - Organic electrodes and electronic devices

Info

Publication number: WO2009052215A1
Application number: PCT/US2008/080046
Authority: WO
Inventors: Jan Bernkopf
Original assignee: Plextronics, Inc.
Priority date: 2007-10-16
Filing date: 2008-10-15
Publication date: 2009-04-23

Abstract

A device comprising: at least one electrode, and at least one organic semiconductor layer, and an interfacial coating disposed between the electrode and the organic semiconductor layer, the coating comprising a polymer comprising regioregular polythiophene comprising (i) at least one organic substituent, and (ii) at least one sulfonate substituent comprising sulfonate sulfur bonding directly to the polythiophene backbone. The device can be a field effect transistor.

Description

ORGANIC ELECTRODES AND ELECTRONIC DEVICES

RELATED APPLICATIONS

This application claims priority to US provisional application serial no. 60/960,851 filed October 16, 2007, which is hereby incorporated by reference in its entirety.

BACKGROUND

Printed electronics is an important, relatively new technology and industry, and one important aspect of this technology is use of organic materials including organic semiconductors (OS) and organic electronic devices. See, for example, Printed Organic and Molecular Electronics, Ed. D. Gamota et al., 2004 ("Gamota"). Printed electronics can allow replacement of conventional photolithographic and microfabrication processes which opens up new avenues of manufacturing. Photolithography is described in for example Microchip Fabrication, 5^ Ed., P. Van Zant, 2004. Microfabrication is described in for example Fundamentals of Microfabrication, 2^nd Ed. M. J. Madou, 2002. For example, solution processing of organic materials can provide for low cost, large area manufacturing on flexible substrates. See for example Sirringhaus, Adv. Mater. 2005, 17, 2411-2425. Printed electronics can provide continuous production processes, fast production speeds, low to moderate capital costs, and small to very large economic run lengths compared to conventional methods.

An important example of an organic material is conducting or conjugated oligomers and polymers including, for example, polyacetylene, polypyrrole, polyaniline, poly(phenylene vinylene), as well as polythiophene, including regioregular polythiophene, as well as copolymers, including block copolymers and copolymers with non-conjugated segments. See, for example, US Patent No. 7,098,294 and 6,166,172 to McCullough et al. (Carnegie-Mellon University) and US Patent Publication Nos. 2006/0076050; 2006/0078761; 2006/0118901; 2006/0175582; 2006/0237695; and 2007/0065590 (Plextronics).

One important device in printed electronics is the transistor including thin film transistors and field effect transistors. These can include source electrode, drain electrode, channel (or semiconductor active layer), gate electrode, and gate insulator (or gate dielectric) structures. However, one important problem with transistors is reducing or eliminating various types of parasitic resistances and capacitances including for example contact resistance. Contact resistance problems easily arise when dissimilar materials contact each other; the same applies when organic materials and inorganic materials contact each other. Better inorganic- organic interfaces are needed. In addition, a need exists to better engineer the organization of OS layers in the channel. A need exists to engineer devices and materials to overcome these and other problems. Both individual materials are needed and combinations of materials which work together.

SUMMARY

Embodiments described herein include compositions, articles, and devices, as well as methods of making and methods of using same.

For example, one embodiment provides a device comprising: at least one electrode, and at least one organic semiconductor layer, and an interfacial coating disposed between the electrode and the organic semiconductor layer, the coating comprising a polymer comprising regioregular polythiophene comprising (i) at least one organic substituent, and (ii) at least one sulfonate substituent comprising sulfonate sulfur bonding directly to the polythiophene backbone. The degree of sulfonation can be less than 100%. For example, the degree of sulfonation can be at least 10% or at least 30% or at least 50%. The device can comprise at least one second electrode.

Another embodiment provides a device comprising: (i) a field effect transistor comprising a source electrode and a drain electrode and at least one organic channel material disposed between the source electrode and the drain electrode, (ii) wherein the source electrode, the drain electrode, or both comprises an interfacial coating between the electrode and the organic channel material comprising a composition comprising: a water soluble or water dispersible regioregular polythiophene comprising (i) at least one organic substituent, and (ii) at least one sulfonate substituent comprising sulfonate sulfur bonding directly to the polythiophene backbone. One or more embodiments described herein can provide one or more advantages. For example, one possible advantage includes reduced contact resistance. Another possible advantage includes improved stability of electronic devices. For example, this can be due to improved stability of the OS/inorganic interface and/or by lowering losses that typically increase the operating temperature of the device.

DETAILED DESCRIPTION All references cited herein are incorporated by reference in their entirety.

PRINTED ELECTRONICS AND FETS

Printed Electronics are generally known in the art. See for example, Printed Organic and Molecular Electronics, Ed. D. Gamota et al., 2004. For example, Chapters 1 and 2 describe organic semiconductors, Chapter 3 describes manufacturing platforms for printing circuits, Chapter 4 describes electrical behavior of transistors and circuits, Chapter 5 describes applications, and Chapter 6 describes molecular electronics. See also Pope et al., Electronic Processes in Organic Crystals and Polymers, 1999.

Field effect transistors, including organic field effect transistors, are generally known in the art and are semiconductor devices comprising an insulated gate electrode which controls current flow through the device. Gate electrode fabrication and FET fabrication are well known in the art. See for example US Patent No. 5,470,767; 6,429,450; 6,593,617; 7,029,945; 7,064,345.

Field effect transistors and testing thereof are known in the art. See for example Sirringhaus et al., Chem. Rev. 2007, 107, 1296-1323; Thin Film Transistors, (Ed. Kagan and Andry), 2003.

US Provisional Application 60/939,356 filed May 21, 2007 describes FETs and reduction in contact resistance. See also Asadi et al., J. Materials Chem., 2007, 17, 1947-1953.

CONDUCTING POLYMERS, HETEROCYCLIC POLYMERS, AND POLYTHIOPHENES In addition, organic and polymer materials are generally known in the art and can be used in the devices, transistors, semiconductive layers, and interfacial coatings as described herein. See, for example, Billmeyer, Textbook of Polymer Science, 3^rd Ed, John Wiley, 1984. Conducting polymers and patterning in field effect transistors is known. See for example US Patent No. 6,331,356. See also H.S. Nalwa, Handbook of Organic Conducting Molecules and Polymers, John Wiley, Chickester, 1997; Salaneck et al., Science and Applications of Conducting Polymers, Adam Hilger, NY 1990. Polythiophenes, including soluble polythiophenes and regioregular polythiophenes, are described in for example US Patent No. 7,098,294 and 6,166,172.

Polythiophenes can be homopolymers, copolymers, or block copolymers. Synthetic methods, doping, and polymer characterization, including regioregular polythiophenes with side groups, is provided in, for example, U.S. Patent Nos. 6,602,974 to McCullough et al. and 6,166,172 to McCullough et al., which are hereby incorporated by reference in their entirety. Additional description can be found in the article, "The Chemistry of Conducting Polythiophenes," by Richard D. McCullough, Adv. Mater. 1998, 10, No. 2, pages 93-116, and references cited therein, which is hereby incorporated by reference in its entirety. Another reference which one skilled in the art can use is the Handbook of Conducting Polymers, 2^nd Ed. 1998, Chapter 9, by McCullough et al., "Regioregular, Head-to-Tail Coupled Poly(3- alkylthiophene) and its Derivatives," pages 225-258, which is hereby incorporated by reference in its entirety.

Polythiophenes are described, for example, in Roncali, J., Cfiem. Rev. 1992, 92, 711; Schopf et al., Polythiophenes: Electrically Conductive Polymers, Springer: Berlin, 1997. See also for example US Patent Nos. 4,737,557 and 4,909,959.

Polymeric semiconductors are described in, for example, "Organic Transistor Semiconductors" by Katz et al., Accounts of Chemical Research, vol. 34, no. 5, 2001, page 359 including pages 365-367, which is hereby incorporated by reference in its entirety.

Block copolymers are described in, for example, Block Copolymers, Overview and Critical Survey, by Noshay and McGrath, Academic Press, 1977. For example, this text describes A-B diblock copolymers (chapter 5), A-B-A triblock copolymers (chapter 6), and -(AB)_n- multiblock copolymers (chapter 7), which can form the basis of block copolymer types in the present invention.

Additional block copolymers including polythiophenes are described in, for example, Francois et al., Synth. Met. 1995, 69, 463-466, which is incorporated by reference in its entirety; Yang et al., Macromolecules 1993, 26, 1188-1190; Widawski et al., Nature (London), vol. 369, June 2, 1994, 387-389; Jenekhe et al., Science, 279, March 20, 1998, 1903-1907; Wang et al., J. Am. Chem. Soc 2000, 122, 6855-6861; Li et al., Macromolecules 1999 , 32, 3034-3044; Hempenius et al., J. Am. Chem. Soc. 1998, 120, 2798-2804;

The following article describes several types of regioregular systems beginning at page 97 and references cited therein: "The Chemistry of Conducting Polythiophenes," by Richard D. McCullough, Adv. Mater. 1998, 10, No. 2, pages 93- 116. In a regioregular polymer, including a polythiophene, the degree of regioregularity can be, for example, about 90% or more, or about 95% or more, or about 98% or more, or about 99% or more. Methods known in the art such as, for example, NMR can be used to measure the degree of regioregularity. Regioregularity can arise in multiple ways. For example, it can arise from polymerization of asymmetric monomers such as a 3-alkylthiophene to provide head- to-tail (HT) poly(3-substituted)thiophene. Alternatively, it can arise from polymerization of monomers which have a plane of symmetry between two portions of monomer such as for example a bi-thiophene, providing for example regioregular HH-TT and TT-HH poly(3-substituted thiophenes).

In particular, substituents or side groups which can be used to solubilize conducting polymers with side chains include alkoxy and alkyl including for example Cl to C25 groups, as well as heteroatom systems which include for example oxygen and nitrogen. In particular, substituents having at least three carbon atoms, or at least five carbon atoms can be used. Mixed substituents can be used. The substituents can be nonpolar, polar or functional organic substituents. The side group can be called a substituent R which can be for example alkyl, perhaloalkyl, vinyl, acetylenic, alkoxy, aryloxy, vinyloxy, thioalkyl, thioaryl, ketyl, thioketyl, and optionally can be substituted with atoms other than hydrogen. Thiophene polymers can be star shaped polymers with the number of branches being for example more than three and comprising thiophene units. Thiophene polymers can be dendrimers. See for example Anthopoulos et al., Applied Physics Letters, 82, 26, June 30, 2003, 4824-4826, and further description of dendrimers hereinafter.

Heterocyclic polymers are particularly preferred. A particularly preferred system is the polythiophene system and the regioregular polythiophene system. Polymers can be obtained from Plextronics, Inc., Pittsburgh, PA including for example polythiophene-based polymers such as for example Plexcore, Plexcoat, and similar materials.

Another embodiment includes heterocyclic conjugated polymers which are relatively regiohregular. For example, the degree of regioregularity can be about 90% or less, or about 80% or less, or about 70% or less, or about 60% or less, or about 50% or less.

ORGANIC SEMICONDUCTOR OR CHANNEL MATERIAL COMPOSITION

In particular, organic channel materials are known in the art. For example, the channel material can comprise a low molecular weight, oligomeric, or polymeric compound or material. P-Type or n-type or ambipolar semiconductors can be used. Mixtures can be used.

The organic semiconductor can be a polythiophene or derivative thereof. It can be a regioregular polythiophene. It can be, for example, alkyl, aryl, or alkoxy substituted including C5 to C12 substituted.

Soluble materials can be used to facilitate solution processing.

Alternatively, materials can be used which can be subjected to vapor deposition.

INTERFACIAL COATING

In one embodiment, the interfacial coating can comprise a hole transport layer, HTL, or charge transport layer, or hole injection layer, HIL, material particularly a conjugated polymer material and a heterocyclic conjugated polymer material. For example, the interfacial coating can comprise materials described in US Patent Application no. 11/826,394 filed May 13, 2007 (Plextronics), which is hereby incorporated by reference including its disclosure of hole injection layer, HIL, materials and preparation of materials and sulfonated polymers. Sulfonated polymer or mixtures of polymer can be used.

For example, the coating can comprise a polymer comprising regioregular polythiophene comprising (i) at least one organic substituent, and (ii) at least one sulfonate substituent comprising sulfonate sulfur bonding directly to the polythiophene backbone. The polymer can be a homopolymer or a copolymer. The polymer can be a block copolymer. The polymer can be substituted at the 3- position.

In another example, the composition can comprise a water soluble or water dispersible regioregular polythiophene comprising (i) at least one organic substituent, and (ii) at least one sulfonate substituent comprising sulfonate sulfur bonding directly to the polythiophene backbone.

An embodiment for the polymer which can be subjected to sulfonation to produce sulfonated substituents on the polymer backbone can be represented by formula (I),

wherein R can be optionally substituted alkyl, optionally substituted alkoxy, and optionally substituted aryloxy. Examples of substituents for the optional substitution include hydroxyl, phenyl, and additional optionally substituted alkoxy groups. The alkoxy groups can be in turn optionally substituted with hydroxyl, phenyl, or alkoxy groups; or wherein R can be an optionally substituted alkylene oxide. Substituents can be for example hydroxyl, phenyl, or alkoxy groups; or wherein R can be optionally substituted ethylene oxide or optionally substituted propylene oxide or other lower alkyleneoxy units. Substituents can be for example hydroxyl, phenyl, or alkoxy groups; or

R can be an optionally substituted alkylene such as for example methylene or ethylene, with substituents being for example optionally substituted alkyleneoxy such as ethyleneoxy or propyleneoxy; substituents can be for example hydroxyl, phenyl, or alkoxy.

Additional descriptions for side groups and definitions and descriptions of side groups can be found in US Patent Application no. 11/826,394 filed May 13, 2007 (Plextronics).

In another embodiment, HIL materials can be used as described in for example US patent application serial no. 11/350,271 filed February 9, 2006.

The compositions can be soluble or dispersible in water or organic solvents. The compositions can be cross-linkable.

METHODS OF MAKING SULFONATED POLYMERS

Described herein also are methods of making compositions and methods of using compositions. For example, one embodiment provides a method for making a composition comprising: reacting a soluble regioregular polythiophene comprising at least one organic substituent with a sulfonation reagent so that the polythiophene comprises at least one sulfonated substituent comprising sulfur bonding directly to the polythiophene backbone. In preferred embodiments, the sulfonation reagent is sulfuric acid; the sulfonation reagent is a sulfate compound; the reacted polythiophene is doped; the reacting results in a degree of sulfonation of at least 10%; the reacting results in a degree of sulfonation of at least 50%; the reacting results in a degree of sulfonation of at least 75%; the sulfonation reagent is sulfuric acid, and the reacting results in a degree of sulfonation of at least 75%; the sulfonation reagent is sulfuric acid, and the reacting results in a degree of sulfonation of at least 75%, and wherein the polythiophene is a regio regular polythiophene having a degree of regioregularity of at least about 90%; and the reacting results in a degree of sulfonation of at least 50%, and wherein the polythiophene is a regio regular polythiophene having a degree of regioregularity of at least about 98%.

The degree of sulfonation can be for example about 10% to about 100%, or about 30% to about 90%, or about 50% to about 90%.

The acid value or acid number (mg KOH/g polymer) can be adapted for an application but can be for example about 250 mg KOH/g polymer, or about 50 to about 250 mg KOH/g polymer, or about 75 to about 200 mg KOH/g polymer, or about 100 to about 150 mg KOH/g polymer. This can be less than competitive polymers such as for example CH8000 which has 651 mg KOH/g solid. A solution formulated for, for example, an HIL application can have an acid value of for example about 0.1 to about 0.8 mg KOH/ g HIL solution, or about 0.2 mg to about 0.6 mg KOH/g HIL solution.

The pH of the formulation can be for example greater than about 2, or about 2.0 to about 3.0, or about 2.3 to about 2.7. This can be less acidic than a variety of competitive materials such as for example Baytron AI4083 which exhibits a pH of about 1.7 and CH8000 which exhibits a pH of about 1.3.

FORMULATION AND BLENDING FOR INTERFACIAL COATING

The conducting polymer and polythiophene compositions, sulfonated as described above, can be formulated and blended by methods known in the art to formulators including, for example, varying the amounts of the components, varying combinations of different structural types, use of different mixing conditions, using different solvents, applying different film preparation conditions, using different purification methods, and the like. Formulations for specific applications in hole injection technology and reduced contact resistance are particularly important.

The blend can be compatible when it is not characterized by excessive phase separation and forms functionally useful, mechanically stable films which can function as a hole injection layer. Compatible blends are known in the art. See, for example, US Patent Nos. 4,387,187; 4,415,706; 4,485,031; 4,898,912; 4,929,388; 4,935,164; and 4,990,557. Compatible blends do not have to be miscible blends, but are sufficiently mixed and stable to provide useful function, particularly in thin film form such as, for example, about 2 nm to about 100 nm. Blending methods may include solution blending of a predissolved conducting polymer either in neutral or oxidized form disintegrated into nanosized particles (typically from tens to hundreds of nanometers) with conventional polymers (e.g., polystyrene (PS), poly(methyl methacrylate) (PMMA), polyvinyl acetate) (PVA)) by sonicating, agitation, or shear. Such blends provide fine dispersion of film-forming submicronic particles of stable polymer matrix solutions. Films can be prepared and analyzed for compatibility by spin coating.

A matrix component can be used which helps provide the needed properties, such as planarization, for the interfacial layer. The matrix component, including planarizing agents, when blended with the hole injection component, will facilitate the formation of the HIL or HTL layer in a device such as a transistor device. It will also be soluble in the solvent that is used to apply the HIL system. The planarizing agent may be comprised of, for example, a polymer or oligomer such as an organic polymer such as poly(styrene) or poly(styrene) derivatives, polyvinyl acetate) or its derivatives, poly(ethylene glycol) or its derivatives, poly(ethylene-co-vinyl acetate), poly(pyrrolidone) or its derivatives (e.g., poly(l-vinylpyrrolidone-co-vinyl acetate)), polyvinyl pyridine) or its derivatives, poly(methyl methacrylate) or its derivatives, poly(butyl acrylate) or its derivatives. More generally, it can be comprised of polymers or oligomers built from monomers such as CH₂CH Ar, where Ar = any aryl or functionalized aryl group, isocyanates, ethylene oxides, conjugated dienes, CH₂CHR₁R (where Ri = alkyl, aryl, or alkyl/aryl functionalities and R = H, alkyl, Cl, Br, F, OH, ester, acid, or ether), lactam, lactone, siloxanes, and ATRP macroinitiators.

More than one non-conductive polymer can be used in the formulation.

The planarizing agent and the hole injection component could be represented by a copolymer that contains an ICP segment and a non-conjugated segment with a composition like similar to that described herein.

The planarizing agent can also be a "non-fugitive", small molecule that is soluble in the application solvent, but does not evaporate upon removal of the solvent. It may possess alkyl, aryl, or functional alkyl or aryl character.

In addition to facilitating the providing of a smooth surface to the HIL layer, the matrix component or planarization agent can also provide other useful functions such as resistivity control and transparency control. Planarity can be determined by methods known in the art including AFM measurements.

The solvent system, or solvents for dispersing polymers, can be a mixture of water and organic solvent, including water miscible solvents, and solvents that comprise oxygen, carbon, and hydrogen, such as for example an alcohol or an etheric alcohol. Additional examples of water miscible solvents include alcohols such as isopropanol, ethanol, and methanol, and ethylene glycols and propylene glycols from Dow Chemical and Eastman Chemical. See for example Cellosolve, Carbitol, propane diol, methyl carbitol, butyl cellosolve, Dowanol PM, In some embodiments, the amount of water can be greater than the amount of organic solvent. A wide variety of combination of solvents can be used including non-aqueous including alcohols and other polar solvents. The composition can comprise a first solvent and a second solvent, different than the first solvent.

In particular, water soluble resins and aqueous dispersions can be used. Aqueous dispersions can be for example poly(styrene sulfonic acid) (i.e. PSS dispersion), Nafion dispersion (e.g., sulfonated fluorinated polymers), latex, and polyurethane dispersions. Examples of water soluble polymers include polyvinylpyrollidinone and polyvinylalcohol. Other examples of resins include cellulose acetate resins (CA, CAB, CAP - Eastman).

Formulation can be carried out to modify surface energy, conductivity, film formation, solubility, crosslinking, morphology, film quality, specific application (e.g, spin coat, ink jet printing, screen printing, and the like).

Surfactants can be used including for example ionic and non-ionic surfactants, as well as polymer surfactants, fluorinated surfactants, and ionomers.

Resins and HIL inks can be dispersed and/or dissolved by any method known in the art including for example sonication.

If desired, the formulation can be formulated to include crosslinking agents which provide crosslinked structures which may swell but not dissolve upon crosslinking.

Preferred embodiments include for example a coating composition comprising: (A) water, (B) a water soluble or water-dispersible regioregular polythiophene comprising (i) at least one organic substituent, and (ii) at least one sulfonate substituent comprising sulfur bonding directly to the polythiophene backbone, and (C) a synthetic polymer different from (B); optionally further comprising an organic co-solvent; or further comprising an organic co-solvent, wherein the weight amount of water is greater than the weight amount of the organic co-solvent; or further comprising a second synthetic polymer different from (B) and (C); wherein the synthetic polymer is a water-soluble polymer; or wherein the synthetic polymer has a carbon backbone with a polar functional group in the side group; or wherein the amount of the synthetic polymer (C) is at least three times the amount of the regioregular polythiophene (B); wherein the amount of the synthetic polymer (C) is at least five times the amount of the regioregular polythiophene (B); or wherein the amount of the regioregular polythiophene polymer (B) is about 5 wt.% to about 25 wt.% with respect to the total amount of (B) and (C); or, and further comprising an organic co-solvent, wherein the weight amount of water is greater than the weight amount of the organic co-solvent, wherein the amount of the synthetic polymer (C) is at least three times the amount of the regioregular polythiophene (B), and wherein the amount of the regioregular polythiophene polymer (B) is about 5 wt.% to about 25 wt.% with respect to the total amount of (B) and (C).

Additional embodiments for materials and polymers that can be added to the formulation include, for example, polyvinyl alcohol), including polyvinyl alcohol) which is 88% hydrolyzed, poly(2-acrylamido-2-methyl-l-propane sulfonic acid), poly(2-acrylamido-2-methyl-l-propane sulfonic acid-co-styrene), poly(l-vinyl pyrolidone-co-vinyl acetate), poly(acrylamide-co-acrylic acid), polyurethane dispersion, acrylic latex dispersion, poly(styrene-ran-ethylene)sulfonated solution, poly(4-vinyl phenol)-co-PMMA, polyvinyl acetate-co-butyl maleate-co-isobornyl acrylate), poly-4-vinylpyridine, and combinations thereof. In some cases, the poly-4- vinylpyridine may not provide as good results as other materials.

In another embodiment, the sulfonated polymer is dissolved or dispersed in water, or a mixture of water and a water soluble organic solvent, or an organic solvent. Optionally, additional ingredients can be mixed in including for example a second type of polymer. The compositions can comprise a first solvent and a second solvent. For example, the first solvent can be water and the second solvent can be an organic solvent miscible with water. These two solvents can be mixed in a wide variety of ratios adapted for a particular application. In some cases, one can eliminate or substantially eliminate the first solvent, or eliminate or substantially eliminate the second solvent. The relative amount (by weight or volume) of the first solvent to second solvent can range from for example 100 parts first solvent and 0 parts second solvent, to 0 parts first solvent and 100 parts second solvent, or 90 parts first solvent and 10 parts second solvent, to 10 parts first solvent and 90 parts second solvent, 80 parts first solvent and 20 parts second solvent, to 20 parts first solvent and 80 parts second solvent, 30 parts first solvent and 70 parts second solvent, to 70 parts first solvent and 30 parts second solvent, 60 parts first solvent and 40 parts second solvent, to 40 parts first solvent and 60 parts second solvent.

For many formulations, the amount of sulfonated polymer is at least about 4 wt.% with respect to the solid content

For some embodiment, the sulfonated polymer can be present with respect to total solid content at about 1 wt. % to about 10 wt.%, or about 4 wt.% to about 8 wt.%.

FABRICATION OF FIELD EFFECT TRANSISTOR AND ELEMENTS THEREOF

FETs are known in the art as well as methods of making them, including organic FETs. See for example, Sirringhaus, "High-Resolution InkJet Printing of All- Polymer Transistor Circuits," Science, vol. 290, Dec 15, 200, 2123-2126; US Patent publication 2005/0023522 to Frey et al.; US Patent No. 7,105,854; 6,723,394 to Sirringhaus.

Known methods of patterning, deposition, and etching can be used. Solution processing methods can be used. Ink Jet printing and other direct write patterning methods can be used to provide the electrodes with interfacial coatings.

EXAMPLE An ink formulation, called Formulation A, comprising the regioregular polythiophene as described in a working example of US Patent Application no. 11/826,394 filed May 13, 2007 (Plextronics) is prepared according to the following recipe and with the following properties:

Formulation A:

Work Function - 5.25 eV (Scanning Kelvin Probe) Resistivity 1 - 6 kOhm-cm

0.3% Conductive Polymer (sulfonated regioregular polythiophene)

1.6% poly(4-viny I phenol)

0.1% polyfluorinated ionomer (nafion)

61.7% water

36.3% butyl cellosolve

Claims

WHAT IS CLAIMED IS:

1. A device comprising: at least one electrode, and at least one organic semiconductor layer, and an interfacial coating disposed between the electrode and the organic semiconductor layer, the coating comprising a polymer comprising regioregular polythiophene comprising (i) at least one organic substituent, and (ii) at least one sulfonate substituent comprising sulfonate sulfur bonding directly to the polythiophene backbone.

2. The device according to claim 1, wherein the polymer is a homopolymer.

3. The device according to claim 1, wherein the polymer is a copolymer.

4. The device according to claim 1, wherein the polymer is a block copolymer.

5. The device according to claim 1, wherein the polymer is water-dispersible, water- swellable, or water-soluble.

6. The device according to claim 1, wherein the polymer is water-soluble.

7. The device according to claim 1, wherein the organic substituent is an alkyl, aryl, or alkoxy substituent.

8. The device according to claim 1, wherein the organic substituent is substituted at the 3-position and is an alkyl, aryl, or alkoxy substituent.

9. The device according to claim 1, wherein the organic semiconductor layer comprises polythiophene.

10. The device according to claim 1, wherein the organic semiconductor layer comprises regioregular polythiophene.

11. The device according to claim 1, wherein the electrode comprises a transparent conductive oxide material.

12. The device according to claim 1, wherein the electrode is a metallic electrode.

13. The device according to claim 1, wherein the device further comprises a substrate, and the electrode is disposed on the substrate.

14. The device according to claim 1, wherein the polymer is a first polymer, and the coating further comprises at least one second polymer which is a synthetic polymer different from the first polymer.

15. The device according to claim 1, wherein the polymer is a first polymer, and the coating further comprises at least one second polymer which is a synthetic polymer different from the first polymer and has a carbon backbone with a polar functional group in the side group.

16. A device comprising: a field effect transistor comprising a source electrode and a drain electrode and at least one organic channel material disposed between the source electrode and the drain electrode, wherein the source electrode, the drain electrode, or both comprises an interfacial coating between the electrode and the organic channel material comprising a composition comprising: a water soluble or water dispersible regioregular polythiophene comprising (i) at least one organic substituent, and (ii) at least one sulfonate substituent comprising sulfonate sulfur bonding directly to the polythiophene backbone.

17. A method of making a device comprising: providing at least one electrode, and at least one organic semiconductor layer material, coating an interfacial coating disposed on the electrode, depositing the organic semiconductor layer on the interfacial coating, wherein the coating comprises a polymer comprising regioregular polythiophene comprising (i) at least one organic substituent, and (ii) at least one sulfonate substituent comprising sulfonate sulfur bonding directly to the polythiophene backbone.

18. A method of improving charge injection, the method comprising placing an interfacial coating between an electrode and an organic semiconductor layer, the coating comprising a polymer comprising regioregular polythiophene comprising (i) at least one organic substituent, and (ii) at least one sulfonate substituent comprising sulfonate sulfur bonding directly to the polythiophene backbone.

19. A method of lowering contact resistance, the method comprising placing an interfacial coating between an electrode and an organic semiconductor layer, the coating comprising a polymer comprising regioregular polythiophene comprising (i) at least one organic substituent, and (ii) at least one sulfonate substituent comprising sulfonate sulfur bonding directly to the polythiophene backbone.

20. A method of improving charge transport, the method comprising placing an interfacial coating between an electrode and an organic semiconductor layer, the coating comprising a polymer comprising regioregular polythiophene comprising (i) at least one organic substituent, and (ii) at least one sulfonate substituent comprising sulfonate sulfur bonding directly to the polythiophene backbone.