WO2007120143A1

WO2007120143A1 - High energy-potential bilayer compositions

Info

Publication number: WO2007120143A1
Application number: PCT/US2006/014551
Authority: WO
Inventors: Che-Hsiung Hsu; Hjalti Skulason
Original assignee: E. I. Du Pont De Nemours And Company
Priority date: 2006-04-18
Filing date: 2006-04-18
Publication date: 2007-10-25
Also published as: KR101279315B1; JP2009534831A; EP2008500A4; EP2008500A1; KR20090009871A

Abstract

There is provided a bilayer composition. The first layer is a hole injection layer having a work function greater than 5.2 eV. The second layer is a hole transport layer. There are also provided electronic devices having the bilayer composition.

Description

TITLE HIGH ENERGY-POTENTIAL BILAYER COMPOSITIONS

BACKGROUND INFORMATION Field of the Disclosure

This invention relates in general to high energy-potential bilayer compositions, and their use in organic electronic devices. Description of the Related Art

Organic electronic devices define a category of products that include an active layer. Such devices convert electrical energy into radiation, detect signals through electronic processes, convert radiation into electrical energy, or include one or more organic semiconductor layers.

Organic light-emitting diodes (OLEDs) are organic electronic devices comprising an organic layer capable of electroluminescence. OLEDs can have the following configuration:

anode/buffer layer/EL material/cathode

The anode is typically any material that is transparent and has the ability to inject holes into the EL material, such as, for example, indium/tin oxide (ITO). The anode is optionally supported on a glass or plastic substrate. EL materials include fluorescent compounds, fluorescent and phosphorescent metal complexes, conjugated polymers, and mixtures thereof. The cathode is typically any material (such as, e.g., Ca or Ba) that has the ability to inject electrons into the EL material. The buffer layer is typically an electrically conducting polymer and facilitates the injection of holes from the anode into the EL material layer. The buffer layer may also have other properties which facilitate device performance. There is a continuing need for buffer materials with improved properties.

SUMMARY

There is provided a bilayer composition. The first layer is a hole injection layer having a work function greater than 5.2 eV. The second layer is a hole transport layer.

In another embodiment, there is provided a bilayer composition. The first layer is a hole injection layer having a work function greater than 5.0 eV and made from a composition having a pH of greater than 2.0. The second layer is a hole transport layer.

In another embodiment, there is provided an electronic device. The device has an anode. The anode is in contact with a hole injection layer having a work function greater than 5.2eV. The hole injection layer is in contact with a hole transport layer.

The foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as defined in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS Embodiments are illustrated in the accompanying figures to improve understanding of concepts as presented herein.

FIG. 1 includes a diagram illustrating contact angle. FIG. 2 includes an illustration of an electronic device having a high energy-potential bilayer composition.

Skilled artisans appreciate that objects in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the objects in the figures may be exaggerated relative to other objects to help to improve understanding of embodiments.

DETAILED DESCRIPTION

Many aspects and embodiments have been described above and are merely exemplary and not limiting. After reading this specification, skilled artisans appreciate that other aspects and embodiments are possible without departing from the scope of the invention.

Other features and benefits of any one or more of the embodiments will be apparent from the following detailed description, and from the claims. The detailed description first addresses Definitions and Clarification of Terms followed by the Hole Injection Layer, the Hole Transport Layer, Methods of Making Bilayer Compositions, Electronic Devices, and finally, Examples.

1. Definitions and Clarification of Terms Used in the Specification and Claims Before addressing details of embodiments described below, some terms are defined or clarified.

As used herein the term "conductor" and its variants are intended to refer to a layer material, member, or structure having an electrical property such that current flows through such layer material, member, or structure without a substantial drop in potential. The term is intended to include semiconductors. In one embodiment, a conductor will form a layer having a conductivity of at least 10^'6 S/cm. The term "electrically conductive material" refers to a material which is inherently or intrinsically capable of electrical conductivity without the addition of carbon black or conductive metal particles.

The term "work function" is intended to mean the minimum energy needed to remove an electron from a conductive or semiconductive material to a point at infinite distance away from the surface. The work- function is commonly obtained by UPS (Ultraviolet Photoemission Spectroscopy) or Kelvin-probe contact potential differential measurement. The term "energy potential" is intended to mean potential of a nonconducting material sandwiched between a conducting specimen and a vibrating tip of Kelvin probe. The conducting specimen can be, but not limited to either gold, indium tin oxide, or electrically conducting polymers. The non-conducting materials in this invention is hole-transporting materials.

The term "hole injection" when referring to a layer, material, member, or structure, is intended to mean such layer, material, member, or structure facilitates injection and migration of positive charges through the thickness of such layer, material, member, or structure with relative efficiency and small loss of charge.

"Hole transport" when referring to a layer, material, member, or structure, is intended to mean such layer, material, member, or structure facilitates migration of positive charges through the thickness of such layer, material, member, or structure with relative efficiency and small loss of charge. As used herein, the term "hole transport layer" does not encompass a light-emitting layer, even though that layer may have some hole transport properties.

In some embodiments, the electrically conductive material is a polymer. The term "polymer" is intended to mean a material having at least one repeating monomeric unit. The term includes homopolymers having only one kind, or species, of monomeric unit, and copolymers having two or more different monomeric units, including copolymers formed from monomeric units of different species. The term "organic solvent wettable" refers to a material which, when formed into a film, is wettable by organic solvents. The term also includes polymeric acids which are not film-forming alone, but which form an electrically conductive polymer composition which is wettable. In one embodiment, organic solvent wettable materials form films which are wettable by phenylhexane with a contact angle no greater than 40°. The term "fluorinated acid polymer" refers to a polymer having acidic groups, where at least some of the hydrogens have been replaced by fluorine. The term "acidic group" refers to a group capable of ionizing to donate a hydrogen ion to a Brønsted base. The composition may comprise one or more different electrically conductive polymers and one or more different organic solvent wettable fluorinated acid polymers.

As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having" or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Further, unless expressly stated to the contrary, "or" refers to an inclusive or and not to an exclusive or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).

Also, use of "a" or "an" are employed to describe elements and components described herein. This is done merely for convenience and to give a general sense of the scope of the invention. This description should be read to include one or at least one and the singular also includes the plural unless it is obvious that it is meant otherwise.

Group numbers corresponding to columns within the Periodic Table of the elements use the "New Notation" convention as seen in the CRC Handbook of Chemistry and Physics, 81^st Edition (2000-2001). Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present invention, suitable methods and materials are described below. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety, unless a particular passage is cited In case of conflict, the present specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.

To the extent not described herein, many details regarding specific materials, processing acts, and circuits are conventional and may be found in textbooks and other sources within the organic light-emitting diode display, lighting source, photodetector, photovoltaic, and semiconductive member arts. 2. Hole Injection Layer

The first layer of the bilayer composition is a hole injection layer. In one embodiment, the hole injection layer has a work function of greater than 5.2 eV. In one embodiment, the hole injection layer was a work function greater than 5.3 eV. In one embodiment, the hole injection layer was a work function greater than 5.5 eV. In one embodiment, the hole injection layer has a work function of greater than 5.0 eV and is formed from a liquid composition having a pH greater than 2. The term "liquid composition" is intended to mean a liquid medium in which a material is dissolved to form a solution, a liquid medium in which a material is dispersed to form a dispersion, or a liquid medium in which a material is suspended to form a suspension or an emulsion. The term "liquid medium" is intended to mean a liquid material, including a pure liquid, a combination of liquids, a solution, a dispersion, a suspension, and an emulsion. Liquid medium is used regardless whether one or more solvents are present. In one embodiment, the liquid medium is a solvent or combination of two or more solvents. Any solvent or combination of solvents can be used so long as a layer of the conductive polymer can be formed. The liquid medium may include other materials, such as coating aids.

In one embodiment the hole injection layer comprises electrically conducting material. Any conductive material can be used so long as the hole injection layer has the desired work function. In one embodiment, the electrically conducting material comprises at least one charge transfer complex. Examples of such complexes include, but are not limited to, complexes of tetracyanoquinodimethane ("TCNQ") with tetrathiafulvalene or tetramethyltetraselenafulvalene. Metal-TCNQ complexes such as Ag-TCNQ, Cu-TCNQ and K-TCNQ can also be used. In one embodiment, the electrically conducting material comprises a semiconductive oxide deposited from a liquid medium. In another embodiment, the semiconductive oxide dispersion is added with a fluorinated acid polymer for increasing the work-function of semiconductive oxides.

In one embodiment, the electrically conducting material comprises at least one conducting polymer. The term "polymer" is intended to refer to compounds having at least three repeating units and encompasses homopolymers and copolymers. In some embodiments, the electrically conductive polymer is conductive in a protonated form and not conductive in an unprotonated form. Any conductive polymer can be used so long as the hole injection layer has the desired work function. In one embodiment, the conductive material comprises at least one conducting polymer doped with at least one fluorinated acid polymer. The term "doped" is intended to mean that the electrically conductive polymer has a polymeric counter-ion derived from a polymeric acid to balance the charge on the conductive polymer. The term "fluorinated acid polymer" refers to a polymer having acidic groups, where at least some of the hydrogens have been replaced by fluorine. The term "acidic group" refers to a group capable of ionizing to donate a hydrogen ion to a Brønsted base. a. Electrically conductive polymers In one embodiment, the electrically conductive polymer will form a film which has a conductivity of at least 10^'7 S/cm. The monomer from which the conductive polymer is formed, is referred to as a "precursor monomer". A copolymer will have more than one precursor monomer. In one embodiment, the conductive polymer is made from at least one precursor monomer selected from thiophenes, selenophenes, tellurophenes, pyrroles, anilines, and polycyclic aromatics. The polymers made from these monomers are referred to herein as polythiophenes, poly(selenophenes), poly(tellurophenes), polypyrroles, polyanilines, and polycyclic aromatic polymers, respectively. The term "polycyclic aromatic" refers to compounds having more than one aromatic ring. The rings may be joined by one or more bonds, or they may be fused together. The term "aromatic ring" is intended to include heteroaromatic rings. A "polycyclic heteroaromatic" compound has at least one heteroaromatic ring. In one embodiment, the polycyclic aromatic polymers are poly(thienothiophenes). In one embodiment, monomers contemplated for use to form the electrically conductive polymer in the new composition comprise Formula I below:

(I)

wherein:

Q is selected from the group consisting of S, Se, and Te; R¹ is independently selected so as to be the same or different at each occurrence and is selected from hydrogen, alkyl, alkenyl, alkoxy, alkanoyl, alkythio, aryloxy, alkylthioalkyl, alkylaryl, arylalkyl, amino, alkylamino, dialkylamino, aryl, alkylsulfinyl, alkoxyalkyl, alkylsulfonyl, arylthio, arylsulfinyl, alkoxycarbonyl, arylsulfonyl, acrylic acid, phosphoric acid, phosphonic acid, halogen, nitro, cyano, hydroxyl, epoxy, silane, siloxane, alcohol, benzyl, carboxylate, ether, ether carboxylate, amidosulfonate, ether sulfonate, ester sulfonate, and urethane; or both R¹ groups together may form an alkylene or alkenylene chain completing a 3, 4, 5, 6, or 7-membered aromatic or alicyclic ring, which ring may optionally include one or more divalent nitrogen, selenium, tellurium, sulfur or oxygen atoms. As used herein, the term "alkyl" refers to a group derived from an aliphatic hydrocarbon and includes linear, branched and cyclic groups which may be unsubstituted or substituted. The term "heteroalkyl" is intended to mean an alkyl group, wherein one or more of the carbon atoms within the alkyl group has been replaced by another atom, such as nitrogen, oxygen, sulfur, and the like. The term "alkylene" refers to an alkyl group having two points of attachment.

As used herein, the term "alkenyl" refers to a group derived from an aliphatic hydrocarbon having at least one carbon-carbon double bond, and includes linear, branched and cyclic groups which may be unsubstituted or substituted. The term "heteroalkenyl" is intended to mean an alkenyl group, wherein one or more of the carbon atoms within the alkenyl group has been replaced by another atom, such as nitrogen, oxygen, sulfur, and the like. The term "alkenylene" refers to an alkenyl group having two points of attachment. As used herein, the following terms for substituent groups refer to the formulae given below:

"alcohol" -R³-OH

"amido" -R³-C(O)N(R⁶) R⁶ "amidosulfonate" -R³-C(O)N(R⁶) R⁴- SO₃Z

"benzyl" -CH₂-C₆H₅

"carboxylate" -R³-C(O)O-Z or -R³-O-C(O)-Z

"ether" -R³-(O-R⁵)_P-O-R⁵ "ether carboxylate" -R³-O-R⁴-C(O)O-Z or -R³-O-R⁴-O-C(O)-Z

"ether sulfonate" -R³-O-R⁴-SO₃Z

"ester sulfonate" -R³-O-C(O)-R⁴-SO₃Z

"sulfonimide" -R³-SO₂-NH- SO₂-R⁵

"urethane" -R³-O-C(O)-N(R⁶)₂ where all "R" groups are the same or different at each occurrence and:

R³ is a single bond or an alkylene group R⁴ is an alkylene group R⁵ is an alkyl group R⁶ is hydrogen or an alkyl group p is 0 or an integer from 1 to 20 Z is H, alkali metal, alkaline earth metal, N(R⁵)₄ or R⁵ Any of the above groups may further be unsubstituted or substituted, and any group may have F substituted for one or more hydrogens, including perfluorinated groups. In one embodiment, the alkyl and alkylene groups have from 1-20 carbon atoms.

In one embodiment, in the monomer, both R¹ together form -O- (CHY)_m-O- , where m is 2 or 3, and Y is the same or different at each occurrence and is selected from hydrogen, halogen, alkyl, alcohol, amidosulfonate, benzyl, carboxylate, ether, ether carboxylate, ether sulfonate, ester sulfonate, and urethane, where the Y groups may be partially or fully fluorinated. In one embodiment, all Y are hydrogen. In one embodiment, the polymer is poly(3,4-ethylenedioxythiophene). In one embodiment, at least one Y group is not hydrogen. In one embodiment, at least one Y group is a substituent having F substituted for at least one hydrogen. In one embodiment, at least one Y group is perfluorinated. In one embodiment, the monomer has Formula l(a):

wherein:

Q is selected from the group consisting of S, Se, and Te;

R⁷ is the same or different at each occurrence and is selected from hydrogen, alkyl, heteroalkyl, alkenyl, heteroalkenyl, alcohol, amidosulfonate, benzyl, carboxylate, ether, ether carboxylate, ether sulfonate, ester sulfonate, and urethane, with the proviso that at least one R⁷ is not hydrogen, and m is 2 or 3. In one embodiment of Formula l(a), m is two, one R⁷ is an alkyl group of more than 5 carbon atoms, and all other R⁷ are hydrogen. In one embodiment of Formula l(a), at least one R⁷ group is fluorinated. In one embodiment, at least one R⁷ group has at least one fluorine substituent. In one embodiment, the R⁷ group is fully fluorinated. In one embodiment of Formula l(a), the R⁷ substituents on the fused alicyclic ring on the monomer offer improved solubility of the monomers in water and facilitate polymerization in the presence of the fluorinated acid polymer.

In one embodiment of Formula l(a), m is 2, one R⁷ is sulfonic acid- propylene-ether-methylene and all other R⁷ are hydrogen. In one embodiment, m is 2, one R⁷ is propyl-ether-ethylene and all other R⁷ are hydrogen. In one embodiment, m is 2, one R⁷ is methoxy and all other R⁷ are hydrogen. In one embodiment, one R⁷ is sulfonic acid difluoromethylene ester methylene (-CH2-O-C(O)-CF2-SO3H), and all other R⁷ are hydrogen.

In one embodiment, pyrrole monomers contemplated for use to form the electrically conductive polymer in the new composition comprise Formula Il below.

where in Formula II:

R¹ is independently selected so as to be the same or different at each occurrence and is selected from hydrogen, alkyl, alkenyl, alkoxy, alkanoyl, alkythio, aryloxy, alkylthioalkyl, alkylaryl, arylalkyl, amino, alkylamino, dialkylamino, aryl, alkylsulfinyl, alkoxyalkyl, alkylsulfonyl, arylthio, arylsulfinyl, alkoxycarbonyl, arylsulfonyl, acrylic acid, phosphoric acid, phosphonic acid, halogen, nitro, cyano, hydroxyl, epoxy, silane, siloxane, alcohol, benzyl, carboxylate, ether, amidosulfonate, ether carboxylate, ether sulfonate, ester sulfonate, and urethane; or both R¹ groups together may form an alkylene or alkenylene chain completing a 3, 4, 5, 6, or 7-membered aromatic or alicyclic ring, which ring may optionally include one or more divalent nitrogen, sulfur, selenium, tellurium, or oxygen atoms; and R² is independently selected so as to be the same or different at each occurrence and is selected from hydrogen, alkyl, alkenyl, aryl, alkanoyl, alkylthioalkyl, alkylaryl, arylalkyl, amino, epoxy, silane, siloxane, alcohol, benzyl, carboxylate, ether, ether carboxylate, ether sulfonate, ester sulfonate, and urethane. In one embodiment, R¹ is the same or different at each occurrence and is independently selected from hydrogen, alkyl, alkenyl, alkoxy, cycloalkyl, cycloalkenyl, alcohol, benzyl, carboxylate, ether, amidosulfonate, ether carboxylate, ether sulfonate, ester sulfonate, urethane, epoxy, silane, siloxane, and alkyl substituted with one or more of sulfonic acid, carboxylic acid, acrylic acid, phosphoric acid, phosphonic acid, halogen, nitro, cyano, hydroxyl, epoxy, silane, or siloxane moieties. In one embodiment, R² is selected from hydrogen, alkyl, and alkyl substituted with one or more of sulfonic acid, carboxylic acid, acrylic acid, phosphoric acid, phosphonic acid, halogen, cyano, hydroxyl, epoxy, silane, or siloxane moieties.

In one embodiment, the pyrrole monomer is unsubstituted and both R¹ and R² are hydrogen. In one embodiment, both R¹ together form a 6- or 7-membered alicyclic ring, which is further substituted with a group selected from alkyl, heteroalkyl, alcohol, benzyl, carboxylate, ether, ether carboxylate, ether sulfonate, ester sulfonate, and urethane. These groups can improve the solubility of the monomer and the resulting polymer. In one embodiment, both R¹ together form a 6- or 7-membered alicyclic ring, which is further substituted with an alkyl group. In one embodiment, both R¹ together form a 6- or 7-membered alicyclic ring, which is further substituted with an alkyl group having at least 1 carbon atom. In one embodiment, both R¹ together form -O-(CHY)_m-O- , where m is 2 or 3, and Y is the same or different at each occurrence and is selected from hydrogen, alkyl, alcohol, benzyl, carboxylate, amidosulfonate, ether, ether carboxylate, ether sulfonate, ester sulfonate, and urethane. In one embodiment, at least one Y group is not hydrogen. In one embodiment, at least one Y group is a substituent having F substituted for at least one hydrogen. In one embodiment, at least one Y group is perfluorinated.

In one embodiment, aniline monomers contemplated for use to form the electrically conductive polymer in the new composition comprise Formula III below.

wherein: a is 0 or an integer from 1 to 4; b is an integer from 1 to 5, with the proviso that a + b = 5; and R¹ is independently selected so as to be the same or different at each occurrence and is selected from hydrogen, alkyl, alkenyl, alkoxy, alkanoyl, alkythio, aryloxy, alkylthioalkyl, alkylaryl, arylalkyl, amino, alkylamino, dialkylamino, aryl, alkylsulfinyl, alkoxyalkyl, alkylsulfonyl, arylthio, arylsulfinyl, alkoxycarbonyl, arylsulfonyl, acrylic acid, phosphoric acid, phosphonic acid, halogen, nitro, cyano, hydroxyl, epoxy, silane, siloxane, alcohol, benzyl, carboxylate, ether, ether carboxylate, amidosulfonate, ether sulfonate, ester sulfonate, and urethane; or both R¹ groups together may form an alkylene or alkenylene chain completing a 3, 4, 5, 6, or 7-membered aromatic or alicyclic ring, which ring may optionally include one or more divalent nitrogen, sulfur or oxygen atoms.

When polymerized, the aniline monomeric unit can have Formula IV(a) or Formula IV(b) shown below, or a combination of both formulae.

where a, b and R¹ are as defined above.

In one embodiment, the aniline monomer is unsubstituted and a = 0.

In one embodiment, a is not 0 and at least one R¹ is fluorinated. In one embodiment, at least one R¹ is perfluorinated.

In one embodiment, fused polycylic heteroaromatic monomers contemplated for use to form the electrically conductive polymer in the new composition have two or more fused aromatic rings, at least one of which is heteroaromatic. In one embodiment, the fused polycyclic heteroaromatic monomer has Formula V:

wherein:

Q is S, Se, Te, or NR⁶; R⁶ is hydrogen or alkyl;

R⁸, R⁹, R¹⁰, and R¹¹ are independently selected so as to be the same or different at each occurrence and are selected from hydrogen, alkyl, alkenyl, alkoxy, alkanoyl, alkythio, aryloxy, alkylthioalkyl, alkylaryl, arylalkyl, amino, alkylamino, dialkylamino, aryl, alkylsulfinyl, alkoxyalkyl, alkylsulfonyl, arylthio, arylsulfinyl, alkoxycarbonyl, arylsulfonyl, acrylic acid, phosphoric acid, phosphonic acid, halogen, nitro, nitrile, cyano, hydroxyl, epoxy, silane, siloxane, alcohol, benzyl, carboxylate, ether, ether carboxylate, amidosulfonate, ether sulfonate, ester sulfonate, and urethane; and at least one of R⁸ and R⁹, R⁹ and R¹⁰, and R¹⁰ and R¹¹ together form an alkenylene chain completing a 5 or 6-membered aromatic ring, which ring may optionally include one or more divalent nitrogen, sulfur.selenium, tellurium, or oxygen atoms.

In one embodiment, the fused polycyclic heteroaromatic monomer has Formula V(a), V(b), V(c), V(d), V(e), V(f), and V(g):

wherein:

Q is S, Se₁ Te, or NH; and T is the same or different at each occurrence and is selected from

S, NR⁶, O, SiR⁶ ₂, Se, Te, and PR⁶; R⁶ is hydrogen or alkyl.

The fused polycyclic heteroaromatic monomers may be further substituted with groups selected from alkyl, heteroalkyl, alcohol, benzyl, carboxylate, ether, ether carboxylate, ether sulfonate, ester sulfonate, and urethane. In one embodiment, the substituent groups are fluorinated. In one embodiment, the substituent groups are fully fluorinated.

In one embodiment, the fused polycyclic heteroaromatic monomer is a thieno(thiophene). Such compounds have been discussed in, for example, Macromolecules, 34, 5746-5747 (2001); and Macromolecules, 35, 7281-7286 (2002). In one embodiment, the thieno(thiophene) is selected from thieno(2,3-b)thiophene, thieno(3,2-b)thiophene, and thieno(3,4-b)thiophene. In one embodiment, the thieno(thiophene) monomer is further substituted with at least one group selected from alkyl, heteroalkyl, alcohol, benzyl, carboxylate, ether, ether carboxylate, ether sulfonate, ester sulfonate, and urethane. In one embodiment, the substituent groups are fluorinated. In one embodiment, the substituent groups are fully fluorinated.

In one embodiment, polycyclic heteroaromatic monomers contemplated for use to form the polymer in the new composition comprise Formula Vl:

wherein: Q is S, Se, Te, or NR⁶;

T is selected from S, NR⁶, O, SiR⁶ ₂, Se, Te, and PR⁶; E is selected from alkenylene, arylene, and heteroarylene; R⁶ is hydrogen or alkyl; R¹² is the same or different at each occurrence and is selected from hydrogen, alkyl, alkenyl, alkoxy, alkanoyl, alkythio, aryloxy, alkylthioalkyl, alkylaryl, arylalkyl, amino, alkylamino, dialkylamino, aryl, alkylsulfinyl, alkoxyalkyl, alkylsulfonyl, arylthio, arylsulfinyl, alkoxycarbonyl, arylsulfonyl, acrylic acid, phosphoric acid, phosphonic acid, halogen, nitro, nitrile, cyano, hydroxyl, epoxy, silane, siloxane, alcohol, benzyl, carboxylate, ether, ether carboxylate, amidosulfonate, ether sulfonate, ester sulfonate, and urethane; or both R¹² groups together may form an alkylene or alkenylene chain completing a 3, 4, 5,

6, or 7-membered aromatic or alicyclic ring, which ring may optionally include one or more divalent nitrogen, sulfur, selenium, tellurium, or oxygen atoms. In one embodiment, the electrically conductive polymer is a copolymer of a precursor monomer and at least one second monomer. Any type of second monomer can be used, so long as it does not detrimentally affect the desired properties of the copolymer. In one embodiment, the second monomer comprises no more than 50% of the polymer, based on the total number of monomer units. In one embodiment, the second monomer comprises no more than 30%, based on the total number of monomer units. In one embodiment, the second monomer comprises no more than 10%, based on the total number of monomer units.

Exemplary types of second monomers include, but are not limited to, alkenyl, alkynyl, arylene, and heteroarylene. Examples of second monomers include, but are not limited to, fluorene, oxadiazole, thiadiazole, benzothiadiazole, phenylenevinylene, phenyleneethynylene, pyridine, diazines, and triazines, all of which may be further substituted.

In one embodiment, the copolymers are made by first forming an intermediate precursor monomer having the structure A-B-C, where A and C represent precursor monomers, which can be the same or different, and B represents a second monomer. The A-B-C intermediate precursor monomer can be prepared using standard synthetic organic techniques, such as Yamamoto, Stille, Grignard metathesis, Suzuki, and Negishi couplings. The copolymer is then formed by oxidative polymerization of the intermediate precursor monomer alone, or with one or more additional precursor monomers. In one embodiment, the electrically conductive polymer is a copolymer of two or more precursor monomers. In one embodiment, the precursor monomers are selected from a thiophene, a selenophene, a tellurophene, a pyrrole, an aniline, and a polycyclic aromatic. b. Fluorinated Acid Polymers The fluorinated acid polymer can be any polymer which is fluorinated and has acidic groups with acidic protons. The term includes partially and fully fluorinated materials. In one embodiment, the fluorinated acid polymer is highly fluorinated. The term "highly fluorinated" means that at least 50% of the available hydrogens bonded to a carbon, have been replaced with fluorine. The acidic groups supply an ionizable proton. In one embodiment, the acidic proton has a pKa of less than 3. In one embodiment, the acidic proton has a pKa of less than 0. In one embodiment, the acidic proton has a pKa of less than -5. The acidic group can be attached directly to the polymer backbone, or it can be attached to side chains on the polymer backbone. Examples of acidic groups include, but are not limited to, carboxylic acid groups, sulfonic acid groups, sulfonimide groups, phosphoric acid groups, phosphonic acid groups, and combinations thereof. The acidic groups can all be the same, or the polymer may have more than one type of acidic group. In one embodiment, the fluorinated acid polymer is water-soluble.

In one embodiment, the fluorinated acid polymer is dispersible in water.

In one embodiment, the fluorinated acid polymer is organic solvent wettable. The term "organic solvent wettable" refers to a material which, when formed into a film, is wettable by organic solvents. In one embodiment, wettable materials form films which are wettable by phenylhexane with a contact angle no greater than 40°. As used herein, the term "contact angle" is intended to mean the angle Φ shown in Figure 1. For a droplet of liquid medium, angle Φ is defined by the intersection of the plane of the surface and a line from the outer edge of the droplet to the surface. Furthermore, angle Φ is measured after the droplet has reached an equilibrium position on the surface after being applied, i.e. "static contact angle". The film of the organic solvent wettable fluorinated polymeric acid is represented as the surface. In one embodiment, the contact angle is no greater than 35°. In one embodiment, the contact angle is no greater than 30°. The methods for measuring contact angles are well known.

In one embodiment, the polymer backbone is fluorinated. Examples of suitable polymeric backbones include, but are not limited to, polyolefins, polyacrylates, polymethacrylates, polyimides, polyamides, polyaramids, polyacrylamides, polystyrenes, and copolymers thereof. In one embodiment, the polymer backbone is highly fluorinated. In one embodiment, the polymer backbone is fully fluorinated. In one embodiment, the acidic groups are sulfonic acid groups or sulfonimide groups. A sulfonimide group has the formula: -SO₂-NH-SO₂-R where R is an alkyl group.

In one embodiment, the acidic groups are on a fluorinated side chain. In one embodiment, the fluorinated side chains are selected from alkyl groups, alkoxy groups, amido groups, ether groups, and combinations thereof.

In one embodiment, the fluorinated acid polymer has a fluorinated olefin backbone, with pendant fluorinated ether sulfonate, fluorinated ester sulfonate, or fluorinated ether sulfonimide groups. In one embodiment, the polymer is a copolymer of 1 ,1-difluoroethylene and 2-(1 ,1-difluoro-2-

(trifluoromethyl)allyloxy)-1 , 1 ,2,2-tetrafluoroethanesulfonic acid. In one embodiment, the polymer is a copolymer of ethylene and 2-(2-(1,2,2- trifluorovinyloxy)-1 ,1 ,2,3,3,3-hexafluoropropoxy)-1 ,1 ,2,2- tetrafluoroethanesulfonic acid. These copolymers can be made as the corresponding sulfonyl fluoride polymer and then can be converted to the sulfonic acid form.

In one embodiment, the fluorinated acid polymer is homopolymer or copolymer of a fluorinated and partially sulfonated poly(arylene ether sulfone). The copolymer can be a block copolymer. Examples of comonomers include, but are not limited to butadiene, butylene, isobutylene, styrene, and combinations thereof.

In one embodiment, the fluorinated acid polymer is a homopolymer or copolymer of monomers having Formula VII:

where: b is an integer from 1 to 5, R¹³ is OH or NHR¹⁴, and

R¹⁴ is alkyl, fluoroalkyl, sulfonylalkyl, or sulfonylfluoroalkyl. In one embodiment, the monomer is "SFS" or SFSI" shown below:

After polymerization, the polymer can be converted to the acid form.

In one embodiment, the fluorinated acid polymer is a homopolymer or copolymer of a trifluorostyrene having acidic groups. In one embodiment, the trifluorostyrene monomer has Formula VIII:

where: W is selected from (CF₂)_b, O(CF₂)_b, S(CF₂)_b, (CF₂)_bO(CF₂)_b, b is independently an integer from 1 to 5, R¹³ is OH or NHR¹⁴, and

R¹⁴ is alkyl, fluoroalkyl, sulfonylalkyl, or sulfonylfluoroalkyl.

In one embodiment, the fluorinated acid polymer is a sulfonimide polymer having Formula IX:

where:

R_f is selected from fluorinated alkylene, fluorinated heteroalkylene, fluorinated arylene, and fluorinated heteroarylene; and n is at least 4.

In one embodiment of Formula IX, R_f is a perfluoroalkyl group. In one embodiment, R_f is a perfluorobutyl group. In one embodiment, R_f contains ether oxygens. In one embodiment n is greater than 10.

In one embodiment, the fluorinated acid polymer comprises a fluorinated polymer backbone and a side chain having Formula X:

OR¹^SO₂-NH-(SO₂-N-SO₂-N)₃-SO₂R¹⁶ (X) H H where:

R¹⁵ is a fluorinated alkylene group or a fluorinated heteroalkylene group;

R¹⁶ is a fluorinated alkyl or a fluorinated aryl group; and a is 0 or an integer from 1 to 4.

In one embodiment, the fluorinated acid polymer has Formula Xl:

where:

R¹⁶ is a fluorinated alkyl or a fluorinated aryl group; c is independently 0 or an integer from 1 to 3; and n is at least 4.

The synthesis of fluorinated acid polymers has been described in, for example, A. Feiring et al., J. Fluorine Chemistry 2000, 105, 129-135; A. Feiring et al., Macromolecules 2000, 33, 9262-9271; D. D. Desmarteau, J. Fluorine Chem. 1995, 72, 203-208; A. J. Appleby et al., J. Electrochem. Soc. 1993, 140(1), 109-111; and Desmarteau, U.S. Patent 5,463,005.

In one embodiment, the fluorinated acid polymer comprises at least one repeat unit derived from an ethylenically unsaturated compound having the structure (XII):

R¹⁷

wherein n is 0, 1 , or 2;

R¹⁷ to R²⁰ are independently H, halogen, alkyl or alkoxy of 1 to 10 carbon atoms, Y, C(RO(RZ)OR²¹, R⁴Y or OR⁴Y; Y is COE², SO₂ E², or sulfonimide; R²¹ is hydrogen or an acid-labile protecting group; Rf¹ is the same or different at each occurrence and is a fluoroalkyl group of 1 to 10 carbon atoms, or taken together are (CF₂)_e where e is 2 to 10; R⁴ is an alkylene group;

E is OH, halogen, or OFc; and

R⁵ is an alkyl group; with the proviso that at least one of R¹⁷ to R²⁰ is Y, R⁴Y or OR⁵Y. R⁴, R⁵, and R¹⁷ to R²⁰ may optionally be substituted by halogen or ether oxygen.

Some illustrative, but nonlimiting, examples of representative monomers of structure (XII) and within the scope of the invention are presented below:

wherein R²¹ is a group capable of forming or rearranging to a tertiary cation, more typically an alkyl group of 1 to 20 carbon atoms, and most typically t-butyl.

Compounds of structure (XII) wherein d = O, structure (Xll-a), may be prepared by cycloaddition reaction of unsaturated compounds of structure (XIII) with quadricyclane (tetracyclo[2.2.1.0^2l60³'⁵]heptane) as shown in the equation below.

The reaction may be conducted at temperatures ranging from about 0 ⁰C to about 200 ⁰C, more typically from about 30 ⁰C to about 150 ⁰C in the absence or presence of an inert solvent such as diethyl ether. For reactions conducted at or above the boiling point of one or more of the reagents or solvent, a closed reactor is typically used to avoid loss of volatile components. Compounds of structure (XII) with higher values of d (i.e., d = 1 or 2) may be prepared by reaction of compounds of structure (XII) with d = 0 with cyclopentadiene, as is known in the art. In one embodiment, the fluorinated acid polymer also comprises a repeat unit derived from at least one ethylenically unsaturated compound containing at least one fluorine atom attached to an ethylenically unsaturated carbon. The fluoroolefin comprises 2 to 20 carbon atoms. Representative fluoroolefins include, but are not limited to, tetrafluoroethylene, hexafluoropropylene, chlorotrifluoroethylene, vinylidene fluoride, vinyl fluoride, perfluoro-(2,2-dimethyl-1 ,3-dioxole), perfluoro-(2-methylene-4-methyl-1 ,3~dioxolane), CF2=CFO(CF2)tCF=CF2, where t is 1 or 2, and Rf"OCF=CF2 wherein Rf" is a saturated fluoroalkyl group of from 1 to about ten carbon atoms. In one embodiment, the comonomer is tetrafluoroethylene.

In one embodiment, the fluorinated acid polymer comprises a polymeric backbone having pendant groups comprising siloxane sulfonic acid. In one embodiment, the siloxane pendant groups have the formula below:

— O_aSi(OH)_b._aR²² ₃__bR²³R_fSO₃H wherein: a is from 1 to b; b is from 1 to 3;

R²² is a non-hydrolyzable group independently selected from the group consisting of alkyl, aryl, and arylalkyl;

R²³ is a bidentate alkylene radical, which may be substituted by one or more ether oxygen atoms, with the proviso that R²³ has at least two carbon atoms linearly disposed between Si and Rf; and

Rf is a perfluoralkylene radical, which may be substituted by one or more ether oxygen atoms.

In one embodiment, the fluorinated acid polymer having pendant siloxane groups has a fluorinated backbone. In one embodiment, the backbone is perfluorinated.

In one embodiment, the fluorinated acid polymer has a fluorinated backbone and pendant groups represented by the Formula (XIV)

— Og- [CF(R_f ²)CF— O_hIi-CF₂CF₂SO₃H (XIV)

wherein R_f ² is F or a perfluoroalkyl radical having 1-10 carbon atoms either unsubstituted or substituted by one or more ether oxygen atoms, h=0 or 1 , i=0 to 3, and g=0 or 1.

In one embodiment, the fluorinated acid polymer has formula (XV)

— (CF₂CF₂)j(CH₂CQ¹ ₂)_k(CQ² ₂ CQ²)- I

Og- [CF(R_f ²)CF₂— Oh]J-CF₂CF₂SO₃H

(XV) where j > 0, k > 0 and 4 < (j + k) < 199, Q¹ and Q² are F or H,

R_f ² is F or a perfluoroalkyl radical having 1-10 carbon atoms either unsubstituted or substituted by one or more ether oxygen atoms, h=0 or 1 , i=0 to 3, g=O or 1. In one embodiment Rf² Js — CF_3, g=1 , h=1 , and i=1. In one embodiment the pendant group is present at a concentration of 3-10 mol-%.

In one embodiment, Q¹ is H, k ≥ 0, and Q² is F, which may be synthesized according to the teachings of Connolly et al., U.S. Patent 3,282,875. In another preferred embodiment, Q¹ is H, Q² is H, g=0, R_f ² is F, h=1 , and 1=1, which may be synthesized according to the teachings of co-pending application serial number 60/105,662. Still other embodiments may be synthesized according to the various teachings in Drysdale et al., WO 9831716(A1), and co-pending US applications Choi et al, WO 99/52954(A1), and 60/176,881.

In one embodiment, the fluorinated acid polymer is a colloid-forming polymeric acid. As used herein, the term "colloid-forming" refers to materials which are insoluble in water, and form colloids when dispersed into an aqueous medium. The colloid-forming polymeric acids typically have a molecular weight in the range of about 10,000 to about 4,000,000. In one embodiment, the polymeric acids have a molecular weight of about 100,000 to about 2,000,000. Colloid particle size typically ranges from 2 nanometers (nm) to about 140 nm. In one embodiment, the colloids have a particle size of 2 nm to about 30 nm. Any colloid-forming polymeric material having acidic protons can be used. In one embodiment, the colloid-forming fluorinated polymeric acid has acidic groups selected from carboxylic groups, sulfonic acid groups, and sulfonimide groups. In one embodiment, the colloid-forming fluorinated polymeric acid is a polymeric sulfonic acid. In one embodiment, the colloid-forming polymeric sulfonic acid is perfluorinated. In one embodiment, the colloid-forming polymeric sulfonic acid is a perfluoroalkylenesulfonic acid.

In one embodiment, the colloid-forming polymeric acid is a highly- fluorinated sulfonic acid polymer ("FSA polymer"). "Highly fluorinated" means that at least about 50% of the total number of halogen and hydrogen atoms in the polymer are fluorine atoms, an in one embodiment at least about 75%, and in another embodiment at least about 90%. In one embodiment, the polymer is perfluorinated. The term "sulfonate functional group" refers to either to sulfonic acid groups or salts of sulfonic acid groups, and in one embodiment alkali metal or ammonium salts. The functional group is represented by the formula -SO₃E⁵ where E⁵ is a cation, also known as a "counterion". E⁵ may be H, Li, Na, K or N(R₁)(R₂)(R₃)(R₄), and R₁, R₂, R3, and R₄ are the same or different and are and in one embodiment H, CH3 or C₂H₅. In another embodiment, E⁵ is H, in which case the polymer is said to be in the "acid form". E⁵ may also be multivalent, as represented by such ions as Ca⁺⁺, and Al⁺⁺⁺. It is clear to the skilled artisan that in the case of multivalent counterions, represented generally as M^x+, the number of sulfonate functional groups per counterion will be equal to the valence "x".

In one embodiment, the FSA polymer comprises a polymer backbone with recurring side chains attached to the backbone, the side chains carrying cation exchange groups. Polymers include homopolymers or copolymers of two or more monomers. Copolymers are typically formed from a nonfunctional monomer and a second monomer carrying the cation exchange group or its precursor, e.g., a sulfonyl fluoride group (-SO₂F), which can be subsequently hydrolyzed to a sulfonate functional group. For example, copolymers of a first fluorinated vinyl monomer together with a second fluorinated vinyl monomer having a sulfonyl fluoride group (-SO₂F) can be used. Possible first monomers include tetrafluoroethylene (TFE), hexafluoropropylene, vinyl fluoride, vinylidine fluoride, trifluoroethylene, chlorotrifluoroethylene, perfluoro(alkyl vinyl ether), and combinations thereof. TFE is a preferred first monomer.

In other embodiments, possible second monomers include fluorinated vinyl ethers with sulfonate functional groups or precursor groups which can provide the desired side chain in the polymer. Additional monomers, including ethylene, propylene, and R-CH=CH₂ where R is a perfluorinated alkyl group of 1 to 10 carbon atoms, can be incorporated into these polymers if desired. The polymers may be of the type referred to herein as random copolymers, that is copolymers made by polymerization in which the relative concentrations of the comonomers are kept as constant as possible, so that the distribution of the monomer units along the polymer chain is in accordance with their relative concentrations and relative reactivities. Less random copolymers, made by varying relative concentrations of monomers in the course of the polymerization, may also be used. Polymers of the type called block copolymers, such as that disclosed in European Patent Application No. 1 026 152 A1 , may also be used.

In one embodiment, FSA polymers for use in the present invention include a highly fluorinated, and in one embodiment perfluorinated, carbon backbone and side chains represented by the formula -(0-CF₂CFRfVO-CF₂CFR_f ⁴SO₃E⁵ wherein Rf³ and R_f ⁴ are independently selected from F₁ Cl or a perfluorinated alkyl group having 1 to 10 carbon atoms, a = 0, 1 or 2, and E⁵ is H, Li, Na, K or N(R1)(R2)(R3)(R4) and R1 , R2, R3, and R4 are the same or different and are and in one embodiment H₁ CH₃ or C2H5. In another embodiment E⁵ is H. As stated above, E⁵ may also be multivalent.

In one embodiment, the FSA polymers include, for example, polymers disclosed in U.S. Patent No. 3,282,875 and in U.S. Patent Nos. 4,358,545 and 4,940,525. An example of preferred FSA polymer comprises a perfluorocarbon backbone and the side chain represented by the formula

-0-CF₂CF(CFS)-O-CF₂CF₂SO₃E⁵ where X is as defined above. FSA polymers of this type are disclosed in U.S. Patent No. 3,282,875 and can be made by copolymerization of tetrafluoroethylene (TFE) and the perfluorinated vinyl ether CF₂=CF-O- CF₂CF(CF₃)-O-CF₂CF₂SO₂F, perfluoro(3,6-dioxa-4-methyl-7- octenesulfonyl fluoride) (PDMOF), followed by conversion to sulfonate groups by hydrolysis of the sulfonyl fluoride groups and ion exchanged as necessary to convert them to the desired ionic form. An example of a polymer of the type disclosed in U.S. Patent Nos. 4,358,545 and 4,940,525 has the side chain -0-CF₂CF₂SO₃E⁵, wherein E⁵ is as defined above. This polymer can be made by copolymerization of tetrafluoroethylene (TFE) and the perfluorinated vinyl ether CF₂=CF-O- CF₂CF₂SO₂F, perfluoro(3-oxa-4-pentenesulfonyl fluoride) (POPF), followed by hydrolysis and further ion exchange as necessary.

In one embodiment, the FSA polymers for use in this invention typically have an ion exchange ratio of less than about 33. In this application, "ion exchange ratio" or ¹¹IXR" is defined as number of carbon atoms in the polymer backbone in relation to the cation exchange groups. Within the range of less than about 33, IXR can be varied as desired for the particular application. In one embodiment, the IXR is about 3 to about 33, and in another embodiment about 8 to about 23.

The cation exchange capacity of a polymer is often expressed in terms of equivalent weight (EW). For the purposes of this application, equivalent weight (EW) is defined to be the weight of the polymer in acid form required to neutralize one equivalent of sodium hydroxide. In the case of a sulfonate polymer where the polymer has a perfluorocarbon backbone and the side chain is -O-CF₂-CF(CF₃)-O-CF2-CF₂-Sθ3H (or a salt thereof), the equivalent weight range which corresponds to an IXR of about 8 to about 23 is about 750 EW to about 1500 EW. IXR for this polymer can be related to equivalent weight using the formula: 50 IXR + 344 = EW. While the same IXR range is used for sulfonate polymers disclosed in U.S. Patent Nos. 4,358,545 and 4,940,525, e.g., the polymer having the side chain -0-CF₂CF₂SO₃H (or a salt thereof), the equivalent weight is somewhat lower because of the lower molecular weight of the monomer unit containing a cation exchange group. For the preferred IXR range of about 8 to about 23, the corresponding equivalent weight range is about 575 EW to about 1325 EW. IXR for this polymer can be related to equivalent weight using the formula: 50 IXR + 178 = EW.

The FSA polymers can be prepared as colloidal aqueous dispersions. They may also be in the form of dispersions in other media, examples of which include, but are not limited to, alcohol, water-soluble ethers, such as tetrahydrofuran, mixtures of water-soluble ethers, and combinations thereof. In making the dispersions, the polymer can be used in acid form. U.S. Patent Nos. 4,433,082, 6,150,426 and WO 03/006537 disclose methods for making of aqueous alcoholic dispersions. After the dispersion is made, concentration and the dispersing liquid composition can be adjusted by methods known in the art.

Aqueous dispersions of the colloid-forming polymeric acids, including FSA polymers, typically have particle sizes as small as possible and an EW as small as possible, so long as a stable colloid is formed. Aqueous dispersions of FSA polymer are available commercially as

Nafion® dispersions, from E. I. du Pont de Nemours and Company (Wilmington, DE).

Some of the polymers described hereinabove may be formed in non-acid form, e.g., as salts, esters, or sulfonyl fluorides. They will be converted to the acid form for the preparation of conductive compositions, described below. c. Preparation of conductive compositions

The new electrically conductive polymer composition is prepared by (i) polymerizing the precursor monomers in the presence of the fluorinated acid polymer; or (ii) first forming the intrinsically conductive copolymer and combining it with the fluorinated acid polymer. fl) Polymerizing precursor monomers in the presence of the fluorinated acid polymer In one embodiment, the electrically conductive polymer composition is formed by the oxidative polymerization of the precursor monomers in the presence of the fluorinated acid polymer. In one embodiment, the precursor monomers comprises two or more conductive precursor monomers. In one embodiment, the monomers comprise an intermediate precursor monomer having the structure A-B-C, where A and C represent conductive precursor monomers, which can be the same or different, and B represents a non-conductive precursor monomer. In one embodiment, the intermediate precursor monomer is polymerized with one or more conductive precursor monomers.

In one embodiment, the oxidative polymerization is carried out in a homogeneous aqueous solution. In another embodiment, the oxidative polymerization is carried out in an emulsion of water and an organic solvent. In general, some water is present in order to obtain adequate solubility of the oxidizing agent and/or catalyst. Oxidizing agents such as ammonium persulfate, sodium persulfate, potassium persulfate, and the like, can be used. A catalyst, such as ferric chloride, or ferric sulfate may also be present. The resulting polymerized product will be a solution, dispersion, or emulsion of the conductive polymer in association with the fluorinated acid polymer. In one embodiment, the intrinsically conductive polymer is positively charged, and the charges are balanced by the fluorinated acid polymer anion.

In one embodiment, the method of making an aqueous dispersion of the new conductive polymer composition includes forming a reaction mixture by combining water, precursor monomer, at least one fluorinated acid polymer, and an oxidizing agent, in any order, provided that at least a portion of the fluorinated acid polymer is present when at least one of the precursor monomer and the oxidizing agent is added.

In one embodiment, the method of making the new conductive polymer composition comprises:

(a) providing an aqueous solution or dispersion of a fluorinated acid polymer;

(b) adding an oxidizer to the solutions or dispersion of step (a); and

(c) adding precursor monomer to the mixture of step (b). In another embodiment, the precursor monomer is added to the aqueous solution or dispersion of the fluorinated acid polymer prior to adding the oxidizer. Step (b) above, which is adding oxidizing agent, is then carried out. In another embodiment, a mixture of water and the precursor monomer is formed, in a concentration typically in the range of about 0.5% by weight to about 4.0% by weight total precursor monomer. This precursor monomer mixture is added to the aqueous solution or dispersion of the fluorinated acid polymer, and steps (b) above which is adding oxidizing agent is carried out.

In another embodiment, the aqueous polymerization mixture may include a polymerization catalyst, such as ferric sulfate, ferric chloride, and the like. The catalyst is added before the last step. In another embodiment, a catalyst is added together with an oxidizing agent. In one embodiment, the polymerization is carried out in the presence of co-dispersing liquids which are miscible with water. Examples of suitable co-dispersing liquids include, but are not limited to ethers, alcohols, alcohol ethers, cyclic ethers, ketones, nitriles, sulfoxides, amides, and combinations thereof. In one embodiment, the co-dispersing liquid is an alcohol. In one embodiment, the co-dispersing liquid is an organic solvent selected from n-propanol, isopropanol, t-butanol, dimethylacetamide, dimethylformamide, N-methylpyrrolidone, and mixtures thereof. In general, the amount of co-dispersing liquid should be less than about 60% by volume. In one embodiment, the amount of co- dispersing liquid is less than about 30% by volume. In one embodiment, the amount of co-dispersing liquid is between 5 and 50% by volume. The use of a co-dispersing liquid in the polymerization significantly reduces particle size and improves filterability of the dispersions. In addition, buffer materials obtained by this process show an increased viscosity and films prepared from these dispersions are of high quality.

The co-dispersing liquid can be added to the reaction mixture at any point in the process.

In one embodiment, the polymerization is carried out in the presence of a co-acid which is a Brønsted acid. The acid can be an inorganic acid, such as HCI, sulfuric acid, and the like, or an organic acid, such as acetic acid or p-toluenesulfonic acid. Alternatively, the acid can be a water soluble polymeric acid such as poly(styrenesulfonic acid), poly(2~acrylamido-2-methyl-1~propanesulfonic acid, or the like, or a second fluorinated acid polymer, as described above. Combinations of acids can be used.

The co-acid can be added to the reaction mixture at any point in the process prior to the addition of either the oxidizer or the precursor monomer, whichever is added last. In one embodiment, the co-acid is added before both the precursor monomers and the fluorinated acid polymer, and the oxidizer is added last. In one embodiment the co-acid is added prior to the addition of the precursor monomers, followed by the addition of the fluorinated acid polymer, and the oxidizer is added last.

In one embodiment, the polymerization is carried out in the presence of both a co-dispersing liquid and a co-acid.

In one embodiment, a reaction vessel is charged first with a mixture of water, alcohol co-dispersing agent, and inorganic co-acid. To this is added, in order, the precursor monomers, an aqueous solution or dispersion of fluorinated acid polymer, and an oxidizer. The oxidizer is added slowly and dropwise to prevent the formation of localized areas of high ion concentration which can destabilize the mixture. The mixture is stirred and the reaction is then allowed to proceed at a controlled temperature. When polymerization is completed, the reaction mixture is treated with a strong acid cation resin, stirred and filtered; and then treated with a base anion exchange resin, stirred and filtered. Alternative orders of addition can be used, as discussed above.

In the method of making the new conductive polymer composition, the molar ratio of oxidizer to total precursor monomer is generally in the range of 0.1 to 2.0; and in one embodiment is 0.4 to 1.5. The molar ratio of fluorinated acid polymer to total precursor monomer is generally in the range of 0.2 to 5. In one embodiment, the ratio is in the range of 1 to 4. The overall solid content is generally in the range of about 1.0% to 10% in weight percentage; and in one embodimentof about 2% to 4.5%. The reaction temperature is generally in the range of about 4°C to 50⁰C; in one embodiment about 20°C to 35°C. The molar ratio of optional co-acid to precursor monomer is about 0.05 to 4. The addition time of the oxidizer influences particle size and viscosity. Thus, the particle size can be reduced by slowing down the addition speed. In parallel, the viscosity is increased by slowing down the addition speed. The reaction time is generally in the range of about 1 to about 30 hours. (ii) Combining intrinsically conductive polymers with fluorinated acid polymers In one embodiment, the intrinsically conductive polymers are formed separately from the fluorinated acid polymer. In one embodiment, the polymers are prepared by oxidatively polymerizing the corresponding monomers in aqueous solution. In one embodiment, the oxidative polymerization is carried out in the presence of a water soluble acid. In one embodiment, the acid is a water-soluble non-flurorinated polymeric acid. In one embodiment, the acid is a non-fluorinated polymeric sulfonic acid. Some non-limiting examples of the acids are poly(styrenesulfonic acid) ("PSSA"), poly(2-acιylamido-2-methyl-1-propanesulfonic acid)

("PAAMPSA"), and mixtures thereof. Where the oxidative polymerization results in a polymer that has positive charge, the acid anion provides the counterion for the conductive polymer. The oxidative polymerization is carried out using an oxidizing agent such as ammonium persulfate, sodium persulfate, and mixtures thereof.

The new electrically conductive polymer composition is prepared by blending the intrinsically conductive polymer with the fluorinated acid polymer. This can be accomplished by adding an aqueous dispersion of the intrinsically conductive polymer to a dispersion or solution of the polymeric acid. In one embodiment, the composition is further treated using sonication or microfluidization to ensure mixing of the components.

In one embodiment, one or both of the intrinsically conductive polymer and fluorinated acid polymer are isolated in solid form. The solid material can be redispersed in water or in an aqueous solution or dispersion of the other component. For example, intrinsically conductive polymer solids can be dispersed in an aqueous solution or dispersion of a fluorinated acid polymer. (iii) pH adjustment

As synthesized, the aqueous dispersions of the new conductive polymer composition generally have a very low pH. In one embodiment, the pH is adjusted to higher values, without adversely affecting the properties in devices. In one embodiment, the pH of the dispersion is adjusted to about 1.5 to about 4. In one embodiment, the pH is adjusted to between 3 and 4.It has been found that the pH can be adjusted using known techniques, for example, ion exchange or by titration with an aqueous basic solution.

In one embodiment, after completion of the polymerization reaction, the as-synthesized aqueous dispersion is contacted with at least one ion exchange resin under conditions suitable to remove decomposed species, side reaction products, and unreacted monomers, and to adjust pH, thus producing a stable, aqueous dispersion with a desired pH. In one embodiment, the as-synthesized aqueous dispersion is contacted with a first ion exchange resin and a second ion exchange resin, in any order. The as-synthesized aqueous dispersion can be treated with both the first and second ion exchange resins simultaneously, or it can be treated sequentially with one and then the other.

Ion exchange is a reversible chemical reaction wherein an ion in a fluid medium (such as an aqueous dispersion) is exchanged for a similarly charged ion attached to an immobile solid particle that is insoluble in the fluid medium. The term "ion exchange resin" is used herein to refer to all such substances. The resin is rendered insoluble due to the crosslinked nature of the polymeric support to which the ion exchanging groups are attached. Ion exchange resins are classified as cation exchangers or anion exchangers. Cation exchangers have positively charged mobile ions available for exchange, typically protons or metal ions such as sodium ions. Anion exchangers have exchangeable ions which are negatively charged, typically hydroxide ions. In one embodiment, the first ion exchange resin is a cation, acid exchange resin which can be in protonic or metal ion, typically sodium ion, form. The second ion exchange resin is a basic, anion exchange resin. Both acidic, cation including proton exchange resins and basic, anion exchange resins are contemplated for use in the practice of the invention. In one embodiment, the acidic, cation exchange resin is an inorganic acid, cation exchange resin, such as a sulfonic acid cation exchange resin. Sulfonic acid cation exchange resins contemplated for use in the practice of the invention include, for example, sulfonated styrene-divinylbenzene copolymers, sulfonated crosslinked styrene polymers, phenol- formaldehyde-sulfonic acid resins, benzene-formaldehyde-sulfonic acid resins, and mixtures thereof. In another embodiment, the acidic, cation exchange resin is an organic acid, cation exchange resin, such as carboxylic acid, acrylic or phosphorous cation exchange resin. In addition, mixtures of different cation exchange resins can be used. In another embodiment, the basic, anionic exchange resin is a tertiary amine anion exchange resin. Tertiary amine anion exchange resins contemplated for use in the practice of the invention include, for example, tertiary-aminated styrene-divinylbenzene copolymers, tertiary- aminated crosslinked styrene polymers, tertiary-aminated phenol- formaldehyde resins, tertiary-aminated benzene-formaldehyde resins, and mixtures thereof. In a further embodiment, the basic, anionic exchange resin is a quaternary amine anion exchange resin, or mixtures of these and other exchange resins. The first and second ion exchange resins may contact the as- synthesized aqueous dispersion either simultaneously, or consecutively. For example, in one embodiment both resins are added simultaneously to an as-synthesized aqueous dispersion of an electrically conducting polymer, and allowed to remain in contact with the dispersion for at least about 1 hour, e.g., about 2 hours to about 20 hours. The ion exchange resins can then be removed from the dispersion by filtration. The size of the filter is chosen so that the relatively large ion exchange resin particles will be removed while the smaller dispersion particles will pass through. Without wishing to be bound by theory, it is believed that the ion exchange resins quench polymerization and effectively remove ionic and non-ionic impurities and most of unreacted monomer from the as-synthesized aqueous dispersion. Moreover, the basic, anion exchange and/or acidic, cation exchange resins renders the acidic sites more basic, resulting in increased pH of the dispersion. In general, about one to five grams of ion exchange resin is used per gram of new conductive polymer composition. In many cases, the basic ion exchange resin can be used to adjust the pH to the desired level. In some cases, the pH can be further adjusted with an aqueous basic solution such as a solution of sodium hydroxide, ammonium hydroxide, tetra-methylammonium hydroxide, or the like.

In another embodiment, more conductive dispersions are formed by the addition of highly conductive additives to the aqueous dispersions of the new conductive polymer composition. Because dispersions with relatively high pH can be formed, the conductive additives, especially metal additives, are not attacked by the acid in the dispersion. Examples of suitable conductive additives include, but are not limited to metal particles and nanoparticles, nanowires, carbon nanotubes, graphite fibers or particles, carbon particles, and combinations thereof. 3. Hole Transport Layer Any hole transport material may be used for the hole transport layer. In one embodiment the hole transport material has an optical band gap equal to or less than 4.2 eV and a HOMO level equal to or less than 6.2 eV with respect to vacuum level.

In one embodiment, the hole transport material comprises at least one polymer. Examples of hole transport polymers include those having hole transport groups. Such hole transport groups include, but are not limited to, carbazole, triarylamines, triarylmethane, fluorene, and combinations thereof. In one embodiment, the hole transport layer comprises a non- polymeric hole transport material. Examples of hole transporting molecules include, but are not limited to: 4,4',4"-tris(N,N-diphenyl~amino)- triphenylamine (TDATA); 4,4',4"-tris(N-3-methylphenyl-N-phenyl-amino)- triphenylamine (MTDATA); N_lN^l-diphenyl-N,N^I-bis(3-methylphenylH1 ,1^I- biphenyl]-4,4'-diamine (TPD); 1,1-bis[(di-4-tolylamino) phenyl]cyclohexane (TAPC); N,N'-bis(4-methylphenyl)-N,N^I-bis(4-ethylphenyl)-[1 ,1^l-(3,3'- dimethyl)biphenyl]-4,4'-diamine (ETPD); tetrakis-(3-methylphenyl)- N.N.N'.N'-Z.δ-phenylenediamine (PDA); α-phenyl-4-N,N- diphenylaminostyrene (TPS); p-(diethylamino)benzaldehyde diphenylhydrazone (DEH); triphenylamine (TPA); bis[4-(N,N- diethylamino)-2-methylphenyl](4-methylphenyl)methane (MPMP); 1-phenyl-3-[p-(diethylamino)styryl]-5-[p-(diethylamino)phenyl] pyrazoline (PPR or DEASP); 1 ,2-trans-bis(9H-carbazol-9-yl)cyclobutane (DCZB); N,N,N^I,N^l-tetrakis(4-methylphenyl)-(1 , 1 '-biphenylH^'-diamine (TTB); N,N'-bis(naphthalen-1-yl)-N,N'-bis-(phenyl)benzidine (α-NPB); and porphyrinic compounds, such as copper phthalocyanine.

In one embodiment, the hole transport layer comprises a material having the Formula XVI:

Formula XVI

wherein

Ar is an arylene group;

Ar', and Ar" are selected independently from aryl groups;

R²⁴ through R²⁷ are selected independently from the group consisting of hydrogen, alkyl, aryl, halogen, hydroxyl, aryloxy, alkoxy, alkenyl, alkynyl, amino, alkylthio, phosphino, silyl, -COR,

COOR, -PO₃R₂, -OPO₃R₂, and CN; R is selected from the group consisting of hydrogen, alkyl, aryl, alkenyl, alkynyl, and amino; and m and n are integers each independently having a value of from 0 to 5, where m + n ≠ 0. In one embodiment of Formula XVI, Ar is an arylene group containing two or more ortf?o-fused benzene rings in a straight linear arrangement.

4. Methods of Making Bilaver Compositions

The hole injection and hole transport layers of the bilayer composition can be made using any technique for forming layers. In one embodiment, the hole injection layer is formed first, and the hole transport layer is formed directly on at least a part of the hole injection layer. In one embodiment, the hole transport layer is formed directly on and covering the entire hole injection layer..

In one embodiment, the hole injection layer is formed on a substrate by liquid deposition from a liquid composition. The term

"substrate" is intended to mean a base material that can be either rigid or flexible and may be include one or more layers of one or more materials.

Substrate materials can include, but are not limited to, glass, polymer, metal or ceramic materials or combinations thereof. The substrate may or may not include electronic components, circuits, conductive members, or layers of other materials.

Any known liquid deposition technique can be used, including continuous and discontinuous techniques. Continuous liquid deposition techniques, include but are not limited to, spin coating, gravure coating, curtain coating, dip coating, slot-die coating, spray coating, and continuous nozzle coating. Discontinuous liquid deposition techniques include, but are not limited to, ink jet printing, gravure printing, flexographic printing and screen printing.

In one embodiment, the hole injection layer is formed by liquid deposition from a liquid composition having a pH greater than 2. In one embodiment, the pH is greater than 4. In one embodiment, the pH is greater than 6.

In one embodiment, the hole transport layer is formed directly on at least a part of the hole injection layer by liquid deposition from a liquid composition.

In one embodiment, the hole transport layer is formed by vapor deposition onto at least a part of the hole injection layer. Any vapor deposition technique can be used, including sputtering, thermal evaporation, chemical vapor deposition and the like. Chemical vapor deposition may be performed as a plasma-enhanced chemical vapor deposition ("PECVD") or metal organic chemical vapor deposition ("MOCVD"). Physical vapor deposition can include all forms of sputtering, including ion beam sputtering, as well as e-beam evaporation and resistance evaporation. Specific forms of physical vapor deposition include rf magnetron sputtering and inductively-coupled plasma physical vapor deposition ("IMP-PVD"). These deposition techniques are well known within the semiconductor fabrication arts.

The thickness of the hole injection layer can be as great as desired for the intended use. In one embodiment, the hole injection layer has a thickness in the range of 100 nm to 200 microns. In one embodiment, the hole injection layer has a thickness in the range of 50 -500 nm. In one embodiment, the hole injection layer has a thickness less than 50nm. In one embodiment, the hole injection layer has a thickness less than 10nm. In one embodiment, the hole injection layer has a thickness that is greater than the thickness of the hole transport layer.

The thickness of the hole transport layer can be a little as a single monolayer. In one embodiment, the thickness is in the range of 100 nm to 200 microns. In one embodiment, the thickness is less than 100 nm. In one embodiment, the thickness is less than 10 nm. In one embodiment, the thickness is less than 1 nm. 5. Electronic Devices In another embodiment of the invention, there are provided electronic devices comprising the bilayer composition. The term "electronic device" is intended to mean a device including one or more organic semiconductor layers or materials. An electronic device includes, but is not limited to: (1) a device that converts electrical energy into radiation (e.g., a light-emitting diode, light emitting diode display, diode laser, or lighting panel), (2) a device that detects a signal using an electronic process (e.g., a photodetector, a photoconductive cell, a photoresistor, a photoswitch, a phototransistor, a phototube, an infrared ("IR") detector, or a biosensors), (3) a device that converts radiation into electrical energy (e.g., a photovoltaic device or solar cell), (4) a device that includes one or more electronic components that include one or more organic semiconductor layers (e.g., a transistor or diode), or any combination of devices in items (1) through (4).

In one embodiment, the electronic device comprises at least one electroactive layer positioned between two electrical contact layers, wherein the device further includes the bilayer. The term "electroactive" when referring to a layer or material is intended to mean a layer or material that exhibits electronic or electro-radiative properties. An electroactive layer material may emit radiation or exhibit a change in concentration of electron-hole pairs when receiving radiation. One type of device is an organic light-emitting diode ("OLED"). One such device is shown in FlG. 2. The device, 100, has an anode layer 110, a buffer layer 120, an electroactive layer 130, and a cathode layer 150. Adjacent to the cathode layer 150 is an optional electron- injection/transport layer 140. The buffer layer is a bilayer as defined herein, comprising a hole injection layer 122 and a hole transport layer 124.

The device may include a support or substrate (not shown) that can be adjacent to the anode layer 110 or the cathode layer 150. Most frequently, the support is adjacent the anode layer 110. The support can be flexible or rigid, organic or inorganic. Examples of support materials include, but are not limited to, glass, ceramic, metal, and plastic films.

The anode layer 110 is an electrode that is more efficient for injecting holes compared to the cathode layer 150. The anode can include materials containing a metal, mixed metal, alloy, metal oxide or mixed oxide. Suitable materials include the mixed oxides of the Group 2 elements (i.e., Be, Mg, Ca, Sr, Ba, Ra), the Group 11 elements, the elements in Groups 4, 5, and 6, and the Group 8-10 transition elements. If the anode layer 110 is to be light transmitting, mixed oxides of Groups 12, 13 and 14 elements, such as indium-tin-oxide, may be used. As used herein, the phrase "mixed oxide" refers to oxides having two or more different cations selected from the Group 2 elements or the Groups 12, 13, or 14 elements. Some non-limiting, specific examples of materials for anode layer 110 include, but are not limited to, indium-tin-oxide ("ITO"), indium-zinc-oxide, aluminum-tin-oxide, gold, silver, copper, and nickel. The anode may also comprise an organic material, especially a conducting polymer such as polyaniline, including exemplary materials as described in "Flexible light-emitting diodes made from soluble conducting polymer," Nature vol. 357, pp 477479 (11 June 1992). At least one of the anode and cathode should be at least partially transparent to allow the generated light to be observed.

The anode layer 110 may be formed by a chemical or physical vapor deposition process or spin-cast process. Chemical vapor deposition may be performed as a plasma-enhanced chemical vapor deposition ("PECVD") or metal organic chemical vapor deposition ("MOCVD"). Physical vapor deposition can include all forms of sputtering, including ion beam sputtering, as well as e-beam evaporation and resistance evaporation. Specific forms of physical vapor deposition include rf magnetron sputtering and inductively-coupled plasma physical vapor deposition ("IMP-PVD"). These deposition techniques are well known within the semiconductor fabrication arts.

In one embodiment, the anode layer 110 is patterned during a lithographic operation. The pattern may vary as desired. The layers can be formed in a pattern by, for example, positioning a patterned mask or resist on the first flexible composite barrier structure prior to applying the first electrical contact layer material. Alternatively, the layers can be applied as an overall layer (also called blanket deposit) and subsequently patterned using, for example, a patterned resist layer and wet chemical or dry etching techniques. Other processes for patterning that are well known in the art can also be used. Depending upon the application of the device, the electroactive layer 130 can be a light-emitting layer that is activated by an applied voltage (such as in a light-emitting diode or light-emitting electrochemical cell), a layer of material that responds to radiant energy and generates a signal with or without an applied bias voltage (such as in a photodetector). In one embodiment, the electroactive material is an organic electroluminescent ("EL") material, Any EL material can be used in the devices, including, but not limited to, small molecule organic fluorescent compounds, fluorescent and phosphorescent metal complexes, conjugated polymers, and mixtures thereof. Examples of fluorescent compounds include, but are not limited to, pyrene, perylene, rubrene, coumarin, derivatives thereof, and mixtures thereof. Examples of metal complexes include, but are not limited to, metal chelated oxinoid compounds, such as tris(8-hydroxyquinolato)aluminum (Alq3); cyclometalated iridium and platinum electroluminescent compounds, such as complexes of iridium with phenylpyridine, phenylquinoline, or phenylpyrimidine ligands as disclosed in Petrov et al., U.S. Patent 6,670,645 and Published PCT Applications WO 03/063555 and WO 2004/016710, and organometallic complexes described in, for example, Published PCT Applications WO 03/008424, WO 03/091688, and WO 03/040257, and mixtures thereof. Electroluminescent emissive layers comprising a charge carrying host material and a metal complex have been described by Thompson et al., in U.S. Patent 6,303,238, and by Burrows and Thompson in published PCT applications WO 00/70655 and WO 01/41512. Examples of conjugated polymers include, but are not limited to poly(phenylenevinylenes), poiyfluorenes, poly(spirobifluorenes), polythiophenes, poly(p-phenylenes), copolymers thereof, and mixtures thereof. Optional layer 140 can function both to facilitate electron injection/transport, and can also serve as a confinement layer to prevent quenching reactions at layer interfaces. More specifically, layer 140 may promote electron mobility and reduce the likelihood of a quenching reaction if layers 130 and 150 would otherwise be in direct contact. Examples of materials for optional layer 140 include, but are not limited to, metal chelated oxinoid compounds, such as bis(2-methyl-8- quinolinolato)(para-phenyl-phenolato)aluminum(lll) (BAIQ) and tris(8-hydroxyquinolato)aluminum (Alq3); azole compounds such as 2-(4- biphenylyl)-5-(4-t-butylphenyl)-1 ,3,4-oxadiazole (PBD), 3-(4-biphenylyl)-4~ phenyl-5-(4-t-butylphenyl)-1 ,2,4-triazole (TAZ), and 1 ,3,5-tri(phenyl-2- benzimidazole)benzene (TPBI); quinoxaline derivatives such as 2,3-bis(4- fluorophenyl)quinoxaline; phenanthroline derivatives such as 9,10- diphenylphenanthroline (DPA) and 2,9-dimethyl-4,7-diphenyl-1 ,10- phenanthroline (DDPA); and any one or more combinations thereof. Alternatively, optional layer 140 may be inorganic and comprise BaO, LiF, U2O, or the like.

The cathode layer 150 is an electrode that is particularly efficient for injecting electrons or negative charge carriers. The cathode layer 150 can be any metal or nonmetal having a lower work function than the first electrical contact layer (in this case, the anode layer 110). As used herein, the term "lower work function" is intended to mean a material having a work function no greater than about 4.4 eV. As used herein, "higher work function" is intended to mean a material having a work function of at least approximately 4.4 eV.

Materials for the cathode layer can be selected from alkali metals of Group 1 (e.g., Li, Na, K, Rb, Cs₁), the Group 2 metals (e.g., Mg, Ca, Ba, or the like), the Group 12 metals, the lanthanides (e.g., Ce, Sm, Eu, or the like), and the actinides (e.g., Th, U, or the like). Materials such as aluminum, indium, yttrium, and combinations thereof, may also be used. Specific non-limiting examples of materials for the cathode layer 150 include, but are not limited to, barium, lithium, cerium, cesium, europium, rubidium, yttrium, magnesium, samarium, and alloys and combinations thereof.

The cathode layer 150 is usually formed by a chemical or physical vapor deposition process. In some embodiments, the cathode layer will be patterned, as discussed above in reference to the anode layer 110. Other layers in the device can be made of any materials which are known to be useful in such layers upon consideration of the function to be served by such layers.

In some embodiments, an encapsulation layer (not shown) is deposited over the contact layer 150 to prevent entry of undesirable components, such as water and oxygen, into the device 100. Such components can have a deleterious effect on the organic layer 130. In one embodiment, the encapsulation layer is a barrier layer or film. In one embodiment, the encapsulation layer is a glass lid.

Though not depicted, it is understood that the device 100 may comprise additional layers. Other layers that are known in the art or otherwise may be used. In addition, any of the above-described layers may comprise two or more sub-layers or may form a laminar structure. Alternatively, some or all of anode layer 110, the hole injection layer 122, the hole transport layer 124, the electron transport layer 140, cathode layer 150, and other layers may be treated, especially surface treated, to increase charge carrier transport efficiency or other physical properties of the devices. The choice of materials for each of the component layers is preferably determined by balancing the goals of providing a device with high device efficiency with device operational lifetime considerations, fabrication time and complexity factors and other considerations appreciated by persons skilled in the art. It will be appreciated that determining optimal components, component configurations, and compositional identities would be routine to those of ordinary skill of in the art.

In one embodiment, the different layers have the following range of thicknesses: anode 110, 500-5000 A, in one embodiment 1000-2000A; the buffer bilayer 120, 100-4000 A, with the hole injection layer 122, 50- 2000 A, in one embodiment 200-1000 A, and the hole transport layer 124, 50-2000 A, in one embodiment 200-1000 A; photoactive layer 130, 10- 2000 A, in one embodiment 100-1000 A; optional electron transport layer 140, 50-2000 A, in one embodiment 100-1000 A; cathode 150, 200-10000 A, in one embodiment 300-5000 A. The location of the electron-hole recombination zone in the device, and thus the emission spectrum of the device, can be affected by the relative thickness of each layer. Thus the thickness of the electron-transport layer should be chosen so that the electron-hole recombination zone is in the light-emitting layer. The desired ratio of layer thicknesses will depend on the exact nature of the materials used.

In operation, a voltage from an appropriate power supply (not depicted) is applied to the device 100. Current therefore passes across the layers of the device 100. Electrons enter the organic polymer layer, releasing photons. In some OLEDs, called active matrix OLED displays, individual deposits of photoactive organic films may be independently excited by the passage of current, leading to individual pixels of light emission. In some OLEDs, called passive matrix OLED displays, deposits of photoactive organic films may be excited by rows and columns of electrical contact layers.

EXAMPLES

The concepts described herein will be further described in the following examples, which do not limit the scope of the invention described in the claims.

General procedure for film sample preparation and Kelvin probe measurement

Film samples of Kelvin probe measurement were made by spin- coating of an aqueous dispersion, or a polymer solution as illustrated in Examples and Comparative Examples on 30 mm x 30 mm glass/ITO substrates. For the bilayer film samples, an aqueous dispersion was first spin-coated on ITO substrates before top-coated with a hole transporting polymer solution. ITO/glass substrates consist of 15 mm x 20 mm ITO area at the center having ITO thickness of 100 to 150nm. At one corner of 15mmx20mm ITO area, ITO film surface extended to the edge of the glass/ITO serves as electrical contact with Kelvin probe electrode. Prior to spin coating, ITO/glass substrates were cleaned and the ITO sides were subsequently treated with Oxygen/plasma for 15 minutes at 0.3Torr at 300watts or UV-ozone for 10 minutes. Once spin-coated, the deposited materials on the corner of the extended ITO film were removed with a Q- tip wetted with either water or Toluene. The exposed ITO pad was for making contact with Kelvin probe electrode. The deposited films were then baked as illustrated in Examples and Comparative Examples. The baked film samples were then placed on a glass jug flooded with nitrogen before capped with a lid before measurement.

For work function, or energy potential measurement, ambient-aged gold film was measured first as a reference prior to measurement of samples. The gold film on a same size of glass piece was placed in a cavity cut out at the bottom of a square steel container. On the side of the cavity, there are four retention clips to keep sample piece firmly in place. One of the retention clips is attached with electrical wire for making contact with the Kelvin probe. The gold film was facing up while a Kelvin probe tip protruded from the center of a steel lid was lowered to above the center of the gold film surface. The lid was then screwed tightly onto the square steel container at four corners. A side port on the square steel container was connected with a tubing for allowing nitrogen to sweep the Kelvin probe cell continuously while a nitrogen exit port capped with a septum in which a steel needle is inserted for maintaining ambient pressure. The probe settings were then optimized for the probe and only height of the tip was changed through entire measurement. The Kelvin probe was connected to a McAllister KP6500 Kelvin Probe meter having the following parameters: 1) frequency: 230; 2) amplitude: 20; 3) DC offset: varied from sample to sample; 4) upper backing potential: 2 volt; 5) lower backing potential: -2 volt; 6) scan rate: 1; 7) trigger delay: 0; 8) acquisition(A)/data(D) points:1024; 9) A/D rate: 12405 @19.0 cycles; 10) D/A: delay: 200; 11) set point gradient: 0.2; 12) step size: 0.001 ; 13) maximum gradient deviation: 0.001. As soon as the tracking gradient stabilized, the contact potential difference ("CPD") in volt between gold film was recorded. The CPD of gold was then referencing the probe tip to (4.7-CPD)eV. The 4.7eV (electron volt) is work function of ambient aged gold film surface [Surface Science, 316, (1994), P380]. The CPD of gold was measured periodically while CPD of samples were being determined. Each sample was loaded into the cavity in the same manner as gold film sample with the four retention clips. On the retention clip making electrical contact with the sample care was taken to make sure good electrical contact was made with the exposed ITO pad at one corner. During the CPD measurement a small stream of nitrogen was flowed through the cell continuously without disturbing the probe tip. Once CPD of sample was recorded, the sample energy potential was then calculated by adding CPD of the sample to the difference of 4.7eV and CPD of gold.

Example 1

This example illustrates the preparation of a high work-function hole-injection material. The hole-injection material is a low pH aqueous dispersion of electrically conducting polypyrrole/Nafion®, where Nafion® is a poly(tetrafluoroethylene)/perfluoroethersulfonic acid).

A 25% (w/w) aqueous colloidal dispersion of Nafion^® having an EW of 1050 was made using a procedure similar to the procedure in U.S. Patent No. 6,150,426, Example 1 , Part 2, except that the temperature was approximately 270°C. The dispersion was diluted with water to form a 12% (w/w) dispersion for the polymerization.

In a 500 mL reaction kettle were put 243.5g of 12% solid content aqueous Nafion® dispersion (29.22 mmol SO₃H groups), and 685g water. The mixture cooled to 5⁰C was stirred at 200 RPM using an overhead stirrer fitted with a double stage propeller blade. The mixture was then added a solution of 604.3mg (1 ,168.6μmol) iron(lll)sulfate (Fe₂(SO₄)₃) in 1OmL deionized water. The reaction mixture was stirred for 15 minutes at 200 RPM before addition of both 2 .5g (10.5mmol) sodium persulfate Na₂S₂O₈ in 20 mL of water, and 809μL(11.69mmol) distilled pyrrole diluted in 2OmL water. The reaction mixture was all first degassed with nitrogen and kept under nitrogen until addition of ion exchange resins. 3 hours after addition of both sodium persulfate and pyrrole, 5Og of each Dowex M31, and Dowex M43 ion exchange resins, andδOg de-ionized water were added to the reaction mixture and stirring it further for 5hrs at 120 RPM. The ion-exchange resins were finally filtered from the suspension through VWR 417 filter paper. pH of the dispersion is 2.18 and films baked at 130⁰C for 10 minutes in air have conductivity of 1.7x10- ²S/cm at room temperature. A sufficient volume of the aqueous dispersion made above was filtered through a 0.45μm HV filter and spin-coated on an ozone-treated ITO/glass surface at 1 ,800RPM for 60 seconds. The ozone treatment of ITO/glass was accomplished by using an UVO-Cleaner Model #256 (2 Mason, Irvine, CA 92718). The film was baked at 130⁰C in air for 10 minutes and was then loaded to the Kelvin probe cell. Contact potential difference (CPD) between the sample and probe tip was measured to be 1.76volt. Work function (Wf) of the polypyrrole/Nafion® is then calculated to be 5.87eV based on a pre-determined CPD of air-aged gold film, which is 0.69volt. The pH 2.18 aqueous polypyrrole/Nafion® is shown to produce high Wf film.

Example 2 This example illustrates high energy potential of a bilayer composition. The bilayer comprises a high work-function hole-injection layer of polypyrrole/Nafion® layer deposited from pH 2.18 dispersion, and a hole transport layer of a crosslinkable polymer of fluorene-triarylamine ("HT-1").

A sufficient volume of the aqueous dispersion of polypyrrole/Nafion® made in Example 1 was filtered through a 0.45μm HV filter and spin-coated onto an ITO/glass surface. The ITO/glass was first treated with plasma/oxygen for 15 minutes at 0.3Torr at 300watts using a O₂-Plasma-25 chamber (Mercator Control Systems, Inc., LF-5 Plasma System). The spin-coated film was then baked at 130⁰C in air for 10 minutes and was determined to be about 20nm (nanometer) by a P-15 model profilometer from KLA-Tencor Corporation (San Jose, CA, USA). This profilometer was also used in the following Examples and Comparative Examples. The polypyrrole/Nafion® on ITO was then top- coated with a 0.4% (w/v) HT-1. The ITO/(polypyrrole/Nafion®)/HT-1 was baked at 200⁰C in nitrogen for 30 minutes to react the crosslinking groups. The crosslinked film was determined to be about 20nm. The glass/ITO/(polypyrrole/Nafion®)/ crosslinked HT-1 was then loaded to the Kelvin probe cell. Contact potential difference (CPD) between the sample and probe tip was measured to be 0.95volt. Energy potential of HT-1 was then calculated to be 4.96eV based on a pre-determined CPD of air-aged gold film, which is 0.69volt. The energy potential was lower than the work function of polypyrrole/Nafion® in Example 1 , but it was shown to be higher than that of the crosslinked HT-1 without polypyrrole/Nafion® underneath as illustrated in Comparative Example A.

Comparative Example A

This example illustrates the low energy potential of HT-1 , when used as a single layer without a high work-function hole-injection material underneath.

A sufficient volume of a 0.4%(w/v) HT-1 in toluene was filtered through a 0.45μm HV filter and spin-coated on an ITO/glass surface. The ITO/glass was first treated with plasma/oxygen for 15 minutes at 0.3Torr at 300watts. The HT-1 film on ITO/glass was baked at 200⁰C in air for 30 minutes to react the crosslinking groups and was determined to be about 18nm. The HT-1 /ITO/glass was then loaded to the Kelvin probe cell. Contact potential difference (CPD) between the sample and probe tip was measured to be 0.26volt. Energy potential of HT-1 film on ITO is then calculated to be 4.27eV based on a pre-determined CPD of air-aged gold film, which is 0.69volt. The energy potential (4.27eV) was lower than that of HT-1/polypyrrole-Nafion®/ITO, which was 4.96eV as illustrated in Example 2.

Example 3

This example illustrates the preparation of a high pH aqueous dispersion of electrically conducting polypyrrole/Nafion®, and its high work function.

A polypyrrole/Nafion® dispersion used in this example was prepared using an aqueous Nafion® colloidal dispersion having an EW (acid equivalent weight) of 1000. The Nafion® dispersion at 25% (w/w) was made using a procedure similar to the procedure in U.S. Patent No. 6,150,426, Example 1 , Part 2, except that the temperature was approximately 270°C and was then diluted with water to form a 12.0% (w/w) dispersion for the polymerization.

In a 4L reaction kettle were put 1 ,704.3g of 12% solid content aqueous Nafion® dispersion (204.51 mmol SO₃H groups), and 1 ,79Og water. The mixture was stirred with a 3 blade overhead stirrer set at

300rpm. The mixture was then added a solution of 4,230. Omg (8.18mmol) iron(lll)sulfate (Fe₂(SO₄)₃) and 17.53g (73.62mmol) sodium persulfate Na₂S₂O₈ dissolved in 150 mL of water. The mixture in the kettle was degassed before addition of 5.66mL(81.8mmol) distilled pyrrole diluted in 15OmL water. The addition of pyrrole was accomplished with four 6OmL syringes. The four syringes of each fed one portion of equal amount of pyrrole to the bottom, one portion at the middle, and two portions at the top of the kettle while stirring at 300rpm. 3.5hrs after addition of the pyrrole solution, 35Og of each Dowex M31, and Dowex M43 ion exchange resins were added to the reaction mixture and stirring it further for 3hrs at 120 RPM. The ion-exchange resins were finally filtered from the suspension through VWR 417 filter paper. pH of the dispersion is 2.32 and films baked at 130⁰C for 10 minutes in air have conductivity of 1.1x10- ²S/cm at room temperature.

A portion of the polypyrrole/Nafion® made above was adjusted to pH 7 with Lewatit Monoplus S100. A sufficient volume of the pH 7 aqueous dispersion was filtered through a 0.45μm HV filter and spin-coated on ITO/glass substrates which were first treated with plasma/oxygen for 15 minutes at 0.3Torr at 300watts. The film was baked at 13O⁰C in air for 10 minutes and was determined to be 20nm. The polypyrrole/Nafion® was then loaded to the Kelvin probe cell. Contact potential difference (CPD) between the sample and probe tip was measured to be 1.27volt. Work function (Wf) of the polypyrrole/Nafion® is then calculated to be 5.28eV based on a pre-determined CPD of air-aged gold film, which is 0.69volt. The pH 7 aqueous dispersion of polypyrrole/Nafion® is shown to produce films having lower Wf lower than the dispersion having pH 2.18 as illustrated in Example 1. But the work function is still high enough to enhance energy potential of HT-1 , which is illustrated in Example 4.

Example 4

This example illustrates high energy -potential of HT-1 on a polypyrrole/Nafion® layer formed from an aqueous dispersion having pH 7. A sufficient volume of pH 7 aqueous dispersion of polypyrrole/Nafion® made in Example 3 was filtered through a 0.45μm HV filter and spin-coated onto a ITO/glass surface. The ITO/glass was first treated with plasma/oxygen for 15 minutes at 0.3Torr at 300watts. The spin-coated film was then baked at 13O⁰C in air for 10 minutes and was determined to be about 20nm (nanometer). The polypyrrole/Nafion® on ITO was then top-coated with a 0.4% (w/v) HT-1 in toluene. HT-1 , a hole- transporting polymer, on polypyrrole/Nafion®/ITO was baked at 200⁰C in nitrogen for 30 minutes to react the crosslinking groups. The crosslinked film was determined to be about 20nm. The glass/ITO/polypyrrole-Nafion®/ crosslinked HT-1 was then loaded to the Kelvin probe cell. Contact potential difference (CPD) between the sample and probe tip was measured to be 0.63volt. Energy potential of HT-1 was calculated to be 4.64eV based on a pre-determined CPD of air-aged gold film, which is 0.69volt. The energy potential (4.64eV) is lower than the work function of polypyrrole/Nafion® (5.28eV) in Example 3, but it was shown higher than the energy potential of the crosslinked HT-1 without a polypyrrole/Nafion® layer underneath as illustrated in Comparative Example B.

Comparative Example B

This comparative example was implemented at the same time as Example 4 to illustrates low energy potential of HT-1 as a single layer without a high work-function hole-injection material underneath. A sufficient volume of a 0.4%(w/v) HT-1 in toluene was filtered through a 0.45μm HV filter and spin-coated on an ITO/glass surface. The ITO/glass was first treated with plasma/oxygen for 15 minutes at 0.3Torr at 300watts. The HT-1 film on ITO/glass was baked at 200⁰C in air for 30 minutes to crosslink the crosslinking groups and was determined to be about 18nm. The HT-1 /ITO/glass was then loaded to the Kelvin probe cell. Contact potential difference (CPD) between the sample and probe tip was measured to be 0.12volt. Work function (Wf) or energy potential of HT-1 film on ITO is then calculated to be 4.13eV based on a pre-determined CPD of air-aged gold film, which is 0.69volt. The energy potential (4.eV) is lower than that of HT-1/polypyrrole/Nafιon®/ITO (4.64eV) illustrated in Example 4. This comparison shows that insertion of a polypyrrole/Nafion® layer between HT-1 and ITO raises the energy potential to facilitate hole injection to the subsequent emitting layers.

Example 5

This example illustrates the high energy-potential of a hole- transporting polymer on a polypyrrole/Nafion® layer made from an aqueous dispersion having pH 2.0. A new batch of polypyrrole/Nafion® having pH 2.0 was made using the recipe described in Example 3, but without adding NaOH. This polypyrrole/Nafion® dispersion forms films having work-function of 5.87eV. Sufficient volume of the aqueous dispersion of polypyrrole/Nafion® was filtered through a 0.45μm HV filter and spin-coated onto a ITO/glass surface at 1 ,000RPM for 60 seconds. The ITO/glass was first treated with plasma/oxygen for 15 minutes at 0.3Torr at 300watts. The spin-coated film was then baked at 120⁰C in air for 10 minutes. The polypyrrole-Nafion® on ITO was then top-coated with a 0.5% (w/v) a hole transporting polymer ("HT-2") in toluene.

C49H36F6N2

Exact Mass: 766.28

MoI. Wt.: 766.81

HT-2 was made according to the procedure in published PCT application WO2005/080525, Example 1. The glass/ITO/polypyrrole-Nafion®/HT-2 was then baked at 195⁰C in an inert box for 30minut.es and then loaded to the Kelvin probe cell. Contact potential difference (CPD) between the sample and probe tip was measured to be 0.58volt. Energy -potential of the HT-2 was calculated to be 4.59eV based on a pre-determined CPD of air-aged gold film, which is 0.69volt. The energy-potential (4.59eV) is lower than work-function (5.87eV) of polypyrrole-Nafion®, but it was shown higher than that of the HT-2 without a polypyrrole-Nafion® layer underneath as illustrated in Comparative Example C.

Comparative Example C

This comparative example was implemented at the same time as Example 5 to illustrate the low energy-potential of HT-2 as a single layer without a high work-function hole-injection layer underneath.

A sufficient volume of a 0.5%(w/v) HT-2 in toluene was filtered through a 0.45μm HV filter and spin-coated on an ITO/glass surface at 1 ,00ORPM for 60 seconds. The glass/ITO was first treated with plasma/oxygen for 15 minutes at 0.3Torr at 300watts. The glass/ITO/ HT-2 was then baked at 195⁰C in an inert box for 30minutes. Thickness of HT-2 was determined to be 19nm and was loaded to the Kelvin probe cell. Contact potential difference (CPD) between the sample and probe tip was measured to be 0.25volt. Energy-potential of HT-2 film on ITO was calculated to be 4.26eV based on a pre-determined CPD of air-aged gold film, which is 0.69volt. The energy potential (4.26eV) is lower than that of HT-2 /polypyrrole-Nafion®/ITO (4.59eV), as illustrated in Example 5. This comparison shows that insertion of a polypyrrole-Nafion® layer between HT-2 and ITO raises the energy potential to facilitate hole injection to the subsequent light emitting layers.

Example 6 This example illustrates effect of pH on work function of electrically conducting poly(3,4-dioxy-ethylenethiophene)/Nafion®, where Nafion® is a poly(tetrafluoroethylene)/perfluoroethersulfonic acid).

A PEDOT-Nafion® dispersion used in this example was prepared using an aqueous Nafion® colloidal dispersion having an EW (acid equivalent weight) of 1050. The Nafion® dispersion at 25% (w/w) was made using a procedure similar to the procedure in U.S. Patent No. 6,150,426, Example 1, Part 2, except that the temperature was approximately 270⁰C and was then diluted with water to form a 12.0% (w/w) dispersion for the polymerization.

In a 500 ml_ reaction kettle are put 63.5g of 12% solid content aqueous Nafion® dispersion (7.26 mmol SO3H groups), 156g water, 13.7 mg (25.4 μmol) iron(lll)sulfate (Fe₂(SO4)₃), and 130 μl_ of 37% HCI (1.58 mmol). The reaction mixture is stirred for 15 minutes at 175 RPM using an overhead stirrer fitted with a double stage propeller type blade before addition of 0.79 g (3.30 mmol) sodium persulfate (Na₂S₂Oe) in 10 mL of water, and 281 μl_ ethylenedioxythiophene (EDT). The addition is started from separate syringes using addition rate of 0.8 mL/h for Na₂S₂O8/water and 20 μl_/h for EDT while continuously stirring at 200 RPM. EDT addition is accomplished by placing the monomer in a syringe connected to a Teflon® tube that leads directly into the reaction mixture. The end of the Teflon® tube connecting the Na₂S₂O₈/water solution is placed above the reaction mixture such that the injection involves individual drops falling from the end of the tube such that the injection is gradual. The reaction is stopped 2 hr after the addition of monomer has finished by adding 15 g of each Lewatit MP62WS and Lewatit Monoplus S100 ion-exchange resins, and 20 g of n- propanol to the reaction mixture and stirring it further for 7 hr at 120 RPM. The ion-exchange resin was finally filtered from the solution using Whatman No. 54 filter paper. pH of the dispersion was 4 and dried films derived from the dispersion had conductivity of 1.4x10"³S/cm at room temperature.

20Og PEDOT-Nafion® obtained above was run through a glass column, which is first filled with 15g of MP62WS and then 15g of Amberlyst 15, a proton- exchange resin. The collected PEDOT-Nafion® has a pH 1.9 and is designated as Ex. 6a. 48g of the pH 1.9 PEDOT- Nation® are added with a diluted NaOH water solution till reaching pH of 4.2. This sample is designated as Ex.6b. 46g of the pH 1.9 PEDOT- Nafion® were added with a diluted NaOH water solution till reaching pH of 6.1. This sample is designated as Ex.6c. The three dispersion samples having pH of 1.9, 4.2 and 6.1 are spin-coated on ITO/glass substrates and dried first to remove water. The dried films are measured for work function (Wf) by Ultraviolet Photoelctron Spectroscopy (UPS), which is a well-known technique. Wf energy level was determined from second electron cut-off with respect to the position of vacuum level using He I (21.22eV) radiation. Table 1 shows that work function (Wf) of PEDOT-Nafion® at pH 1.9 is higher (5.9eV vs. 5.1eV) than that of Baytron-P of pH 1.8 illustrated in Comparative Example C. Although Wf decreases to 5.5eV and 5.3eV at pH of 4.2, and 6.1 , respectively, the Wf is still much higher that of Baytron-P at three pH levels. The comparison clearly shows that PEDOT-Nafion® is much less sensitive to pH than Baytron-P and still maintains high Wf at high pH.

Table ! Work function of PEDOT- Nafion® at three pH levels

Comparative Example D

This example illustrates the effect of pH on the work function of

Baytron-P^® AI4083 (Lot# CHDSPS0006; solid:1.48%, pH=1.8), an aqueous dispersion of electrically conducting poly(3,4- dioxyethylenethiophene)/polystyrenesulfonic acid, which is not a fluoropolymeric acid. Baytron-P AI4083 from H. C. Starck, GmbH, Leverkuson, Germany, is a PEDOT-PSSA, poly(3,4-dioxy-ethylenethiophene)- poly(styrenesulfonic acid). 8Og Baytron-P AI4083 were added with 4g each of Lewatit S100 and MP 62 WS for 20 minutes. Lewatit® S100, a trade names from Bayer, Pittsburgh, PA, for sodium sulfonate of crosslinked polystyrene. Lewatit® MP62 WS, a trade from Bayer, Pittsburgh, PA, for free base/chloride of tertiary/quaternary amine of crosslinked polystyrene. The resins in the Baytron-P were removed by filtration through VWR #417 filter paper (40μm). The pH was measured to be 2.2 and was adjusted to 3.95 by the addition of 1.0M NaOH aqueous solution. Half of the sample is designated as comp. D-a (see Table 2). The other half was further adjusted with the 1.0M NaOH solution to pH of 7. This sample is designated as comp.D-b.

Comp. D-a and D-b and AI4083 were spin-coated on ITO/glass substrates and dried first to remove water. The dried films were measured for work function (Wf) by Ultraviolet Photoelctron Spectroscopy (UPS). Wf energy level is determined from second electron cut-off with respect to the position of vacuum level using He I (21.22eV) radiation. The data shows that as-received Baytron-P has work function of 5.1eV (electron volt), which is low, and decreases to 4.7eV as pH increases to 4 and 7. This comparative examples shows that Baytron-P is not a high work-function conducting polymer at low pH and its function drops down to lower level as pH increases.

Table 2. Work function of Baytron-P AI4083 at three pH levels

Example 7 This example illustrates the addition of Nafion®, a poly(tetrafluoroethylene/ perfluoroethersulfonic acid), to increase work function of Baytron-P^® AI4083

Baytron-P^® AI4083 (Lot# CHDSPS0006; solid: 1.48%, pH=1.77) was used to form a blend with Nafion^®. AI4083 is PEDOT/PSSA from H. C. Starck, GmbH, Leverkusen, Germany. The w/w ratio between PEDOT/PSSA is 1:6. The Nafion® used for the blending is an aqueous colloidal dispersion with an EW of 1050 and was made as followed. A 25% (w/w) Nafion^® was made first using a procedure similar to the procedure in US Patent 6,150,426, Example 1 , Part 2, except that the temperature was approximately 270°C. The Nafion^® dispersion was then diluted with water to form 12.0 % (w/w) dispersion for the use of this invention.

330.94g of the Nafion® was dripped in to mix with 1269.59g Baytron-P^® in a flask while being stirred with a magnetic stirrer. It took about 5 hours to complete the addition. The resulting dispersion contained 3.66% solid in which the equivalent ratio of

Nafion®/PEDT/PSSA is 2.0/1.0/4.6. The mixture was further processed with a Microfluidizer Processor M-110EH (Microfluidics, Massachusetts, USA) using a pressure of 8,000 psi. The diameters of first chamber and second chamber were 200μm (H30Z model), and 87μm (G10Z), respectively. In one pass, the PSC was reduced from 693,000 to

-240,000. The microfluidized mixture had a film (baked at 90⁰C for 40 minutes) conductivity of 7.7x10^"6S/cm.

A small portion of the microfluidized dispersion was ran through a 100 ml_ column packed with Monoplus S100 on the bottom and MP 62 WS on top. The two resins were washed first before use with deionized water separately until there was no color in the water. The pH of the resin-treated dispersion is 1.98 and has film (baked at 90⁰C for 40 minutes) conductivity of 1.4x10^'5S/cm. Couple drops of the dispersion were spin-coated on ITO/glass substrates and dried first to remove water. The dried films were measured for work function (Wf) by Ultraviolet

Photoelctron Spectroscopy (UPS) and measured to be 5.8eV. The work function is much higher than Baytron-P used in the formulation of blending.

Example 8

This example illustrates high work function compositions of polyaniline made in the presence of a sulfonic acid converted from 1,1- difluoroethylene ("VF₂") and 2(1,1-difluoro-2-(trifluoromethyl)allyloxy)- 1 ,1 ,2,2-tetrafluoroethanesulfonyI fluoride ("VF₂-PSEBVE"). VF₂-PSEBVE sulfonic acid forms organic-solvent wettable surfaces.

Ingredient Structure and Glossary: ^Fv^F Ii ^Fv^CF3FV^F V -Y o'Vo f HFPO-dimer peroxide

^F F F F F CF₃ O F F

2-(1,1-difluoro-2-(trifluoromethyl)allyloxy)- 1,1,2,2-tetrafluoroethanesulfonyl fluoride

(PSEBVE)

^H^₌/ 1 ,1-difluoroethylene ι/ > (VF2)

Vertrel(R) XF

A 400 ml_ Hastelloy C276 reaction vessel was charged with 160 ml_ of Vertrel® XF, 4 mL of a 20 wt.% solution of HFPO dimer peroxide in Vertrel® XF, and 143 g of PSEBVE (0.42 mol). The vessel was cooled to -35 ⁰C, evacuated to -3 PSIG, and purged with nitrogen. The evacuate/purge cycle was repeated two more times. To the vessel was then added 29 g VF₂ (0.45 mol). The vessel was heated to 28⁰C, which increased the pressure to 92 PSIG. The reaction temperature was maintained at 28⁰C for 18 h. at which time the pressure had dropped to 32 PSIG. The vessel was vented and the crude liquid material was recovered. The Vertrel® XF was removed in vacuo to afford 110 g of desired copolymer. Conversion of the sulfonyl fluoride copolymer prepared above to sulfonic acid was carried out in the following manner. 20 g of dried polymer and 5.0 g lithium carbonate were refluxed in 100 mL dry methanol for 12 h. The mixture was brought to room temperature and filtered to remove any remaining solids. The methanol was removed in vacuo to isolate the lithium salt of the polymer. The lithium salt of the polymer was then dissolved in water and added with Amberlyst 15, a protonic acid exchange resin which had been washed thoroughly with water until there was no color in the water. The mixture was stirred and filtered. Filtrate was added with fresh Amberlyst 15 resin and filtered again. The step was repeated two more times. Water was then removed from the final filtrates and the solids were then dried in a vacuum oven. The VF2/PSEBVE acid polymer was then dissolved in water to prepare a 4.39% (w/w) solution for polymerization with aniline shown below. 78.61 g of deionized water and 45.38g of 99.7% n-propanol were massed directly into a 1,00OmL reactor vessel at room temperature. Next, 0.0952ml_ (1.2mmol) of 37% wt. HCI and 0.6333ml_ (7.0mmol) of aniline (distilled) were added to the reactor via pipet. The mixture was stirred overhead with a U-shaped stir-rod set at 100RPM. After five minutes, 53.6Og of 4.39% water solution of the VF2/PSEBVE sulfonic acid polymer (5.80mmol) was added slowly via a glass funnel. The mixture was allowed to homogenize at 200rpm for an additional 10 minutes. 1.65g (7.2mmol) of ammonium persulfate (99.99+%) dissolved in 20 g of Dl water was added drop wise to the reactants via syringe infusion pump in six hours. Eight minutes later the solution turned light turquoise. The solution progressed to being dark blue before turning very dark green. After the APS addition, the mixture was stirred for 60 minutes and 4.68g of Amberlyst-15 (Rohm and Haas Co., Philadelphia, PA) cation exchange resin (rinsed multiple times with a 32% n-propanol/DI water mixture and dried under nitrogen) was added and the stirring commenced overnight at 200 RPM. The next morning, the mixture was filtered through steel mesh. pH of the Amberlyst 15 treated dipsersion was 1.2. A portion of the dispersion was stirred with Amberjet 4400 (OH) (Rohm and Haas Co., Philadelphia, PA) anion exchange resin (rinsed multiple times with a 32% n-propanol/DI water mixture and dried under nitrogen) until the pH had changed from 1.2 to 5.7. The resin was again filtered off and the filtrate was a stable dispersion.

Couple drops of the Pani dispersion was spin-coated on an ITO/glass substrates. The dried film on ITO was measured for work function by Ultraviolet Photoelectron Spectroscopy and measured to be 5.5eV. The work function is high at pH 5.7.

Example 9 This example illustrates a polymeric light emitting diode utilizing a high energy-potential bilayer. The bilayer consists of a first layer of polypyrrole/Nafion spin-coated with a second layer of HT-1. As shown in Example 4, HT-1 top-coated on polypyrrole/Nafion® having high pH has high energy-potential. This bilayer surface was used to make polymeric light emitting diodes using a red light-emitting material.

Sufficient volume of the aqueous dispersion of polypyrrole/Nafion® was filtered through a 0.45μm HV filter and spin-coated onto glass/ITO backlight substrates (30mmx30mm) for making light emitting diodes. Each ITO substrate having ITO thickness of 100 to150nm consists of 3 pieces of 5mmx5mm pixels and 1 piece of 2mmx2mm pixel for light emission. Once spin-coated onto the ITO substrates, the films were baked first at 120°C in air for 10 minutes. The baked film has a thickness of 12nm and work- function is 5.3eV as shown in Example 3. The polypyrrole/ ITO substrates were spin-coated at 2,000RPM for 60 seconds with a crosslinkable polymer solution (0.4% w/v in Toluene) of HT-1. The crosslinkable polymer was subsequently baked at 198⁰C for 30 minutes in nitrogen to form a hole transporting layer (HTL). The film thickness was measured to be approximately 20nm. The HTL was then top-coated with a 1%(w/v) solution (in Toluene) with a red electroluminescent polymer and subsequently baked at 130⁰C in nitrogen for 30 minutes to form a film thickness of 70nm. Following the baking, a cathode consisting of 3nm of Ba and 250nm of Al was thermally evaporated at pressure less then 4x10^"

⁶Torr. Encapsulation of the devices was achieved by bonding a glass slide on the back of the devices using an UV-curable epoxy resin.

Table 2 summarizes light emitting device efficiency and voltage at 200, 500, 1 ,000nits (Cd/m²) and lifetime from 1 ,200nits to 1 ,000nits. The data shows that the high surface energy-potential bilayer has better device efficiency, lower voltage, and much longer lifetime than that of the hole transporting layer without a high work-function hole injection layer underneath as illustrated in comparative Example E.

Comparative Example E:

This example illustrates a polymeric light emitting diode made with a hole-transporting layer having low energy-potential. As shown in Comparative Example B, HT-1 has low surface- energy potential without a high work-function hole-injection layer undenearth. ITO substrates were only spin-coated with HT-1 for making polymeric light emitting diodes. The device fabrication procedure described in Example 9, including each layer sequence, baking temperature and layer thickness, was closely followed. Device efficiency and lifetime are summarized in Table 2. It clearly shows that ITO without polypyrrole/Nafion layer underneath HT-1 layer has lower device efficiency, higher voltage, and much shorter lifetime than that of the bilayer as illustrated in Examples 9.

Table 2 Effect of energy-potential bilayer on device efficiency, voltage, and lifetime

Comparative Example F

This comparative example illustrates the work function of ITO. ITO substrates used for illustration of Examples and Comparative Examples were treated either with UV-ozone for 10 minutes or with oxygen/plasma for 15 minutes at 0.3Torr at 300watts. The treated ITO sample was loaded o the Kelvin probe cell with ITO facing the Kelvin probe tip. Contact potential difference (CPD) between UV/ozone treated ITO and probe tip was measured to be 0.805volt. Work-function of the surface was then calculated to be 4.9eV based on a pre-determined CPD of gold film, which was 0.69volt. CPD between oxygen-plasma treated ITO and probe tip was measured to be as high as 1.17volt. Work-function of the ITO surface was then calculated to be 5.2eV based on a pre-determined CPD of gold film, which was 0.69volt. The work-function was not stable and decreased at least 0.2eV when exposed to air or solvent such as toluene. This comparative example shows that ITO alone is not sufficient to form a high energy-potential on a hole-transporting layer.

Note that not all of the activities described above in the general description or the examples are required, that a portion of a specific activity may not be required, and that one or more further activities may be performed in addition to those described. Still further, the order in which activities are listed are not necessarily the order in which they are performed.

In the foregoing specification, the concepts have been described with reference to specific embodiments. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the invention as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of invention. Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any feature(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature of any or all the claims.

It is to be appreciated that certain features are, for clarity, described herein in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features that are, for brevity, described in the context of a single embodiment, may also be provided separately or in any subcombinatiσn. Further, reference to values stated in ranges include each and every value within that range.

Claims

CLAIMS What is claimed is:

1. A bilayer composition comprising: a hole injection layer having a work function greater than 5.2 eV, and a hole transport layer.

2. A bilayer composition of claim 1 wherein the hole injection layer comprises at least one electrically conductive material selected from the group consisting of charge transfer complexes and conducting polymers.

3. A bilayer composition of claim 2 wherein the charge transfer complex is selected from the group consisting of tetracyanoquinodimethane complexes with tetrathiafulvalene or tetramethyltetraselenafulvalene, metal-tetracyanoquinodimethane complexes, and a semiconductive oxide deposited from a liquid medium.

4. A bilayer composition of claim 2 wherein the conducting polymer is formed from at least one monomer selected from the group consisting of thiophenes, selenophenes, tellurophenes, pyrroles, anilines, and polycyclic aromatics.

5. A bilayer composition of claim 3 wherein the semiconductive oxide is deposited with at least one fluorinated acid polymer.

6. A bilayer composition of claim 4 wherein the conducting polymer is doped with at least one fluorinated acid polymer.

7. A bilayer composition of claim 5 wherein the fluorinated acid polymer has a perfluorinated carbon backbone and side chains represented by the formula:

-(O-CF₂-CFR_f ³)_a-O-CF₂-CFR_f ⁴-SO₃-E⁵- wherein R_f ³ and R_f ⁴ are independently selected from the group consisting of F, Cl and a perfluorinated alkyl group having 1 to 10 carbon atoms; a = 0, 1 or 2; and E⁵ is H.

8. A bilayer composition of claim 6 wherein the fluorinated acid polymer has a perfluorinated carbon backbone and side chains represented by the formula:

9. A bilayer composition of claim 1 wherein the hole transport layer is crosslinkable.

10. A bilayer composition of claim 1 wherein the hole injection layer has a work function greater than 5.3 eV.

11. A bilayer composition of claim 1 wherein the hole injection layer has a work function greater than 5.5 eV.

12. A bilayer composition comprising: a hole injection layer having a work function greater than 5.0 eV and made from a composition having a pH of greater than 2.0, and a hole transport layer.

13. An electronic device comprising: an anode, in contact with a hole injection layer having a work function greater than 5.2 eV, in contact with a hole transport layer.

14. A bilayer composition of claim 3 wherein the hole transport layer comprises at least one polymer having a hole transport group selected from the group consisting of carbazole, triarylamines, triarylmethane, fluorene, and combinations thereof.

15. A bilayer composition of claim 4 wherein the hole transport layer comprises at least one polymer having a hole transport group selected from the group consisting of carbazole, triarylamines, triarylmethane, fluorene, and combinations thereof.

16. A bilayer composition of claim 3 wherein the hole transport layer comprises a non-polymeric material selected from the group consisting of 4,4',4"-tris(N,N-diphenyl-amino)-triphenylamine; 4,4',4"-tris(N- 3-methylphenyl-N-phenyl-amino)-triphenylamine; N,N'-diphenyl-N,N^l-bis(3- methylphenylHI .I'-biphenylH^'-diamine; 1 ,1-bis[(di-4-tolylamino) phenyl]cyclohexane; N,N'-bis(4-methylphenyl)-N,N'-bis(4-ethylphenyl)- [1 , 143,3'-dimethyl)biphenyl]-4,4'-diamine; tetrakis-(3-methylphenyl)- N,N,N\N'-2,5-phenylenediamine; α-phenyl-4-N,N-diphenylaminostyrene; p-(diethylamino)benzaldehyde diphenylhydrazone; triphenylamine; bis[4-(N,N-diethylamino)-2-methylphenyl](4-methylphenyl)methane; 1-phenyl-3-[p-(diethylamino)styryl]-5-[p-(diethylamino)phenyl] pyrazoline; 1,2-trans-bis(9H-carbazol-9-yl)cyclobutane; N,N,N^l,N^l-tetrakis(4-methyl- phenyl)-(1,1'-biphenyl)-4,4'-diamine; N,N'-bis(naphthalen-1-yl)-N,N'-bis- (phenyl)benzidine; porphyrinic compounds, and compounds represented by Formula XVI:

Formula XVI

wherein

Ar is an arylene group; Ar', and Ar" are selected independently from aryl groups;

R²⁴ through R²⁷ are selected independently from the group consisting of hydrogen, alkyl, aryl, halogen, hydroxy!, aryloxy, alkoxy, alkenyl, alkynyl, amino, alkylthio, phosphino, silyl, -COR, - COOR, -PO₃R₂, -OPO₃R₂, and CN; R is selected from the group consisting of hydrogen, alkyl, aryl, alkenyl, alkynyl, and amino; and m and n are integers each independently having a value of from O to 5, where m + n ≠ O.

17. A bilayer composition of claim 4 wherein the hole transport layer comprises a non-polymeric material selected from the group consisting of 4,4\4"-tris(N,N-diphenyl-amino)-triphenylamine; 4,4',4"-tris(N- 3-methylphenyl-N-phenyl-amino)-triphenylamine; N,N'-diphenyl-N,N'-bis(3- methylphenyl)-[1 ,1'-biphenyl]-4,4'-diamine; 1,1-bis[(di-4-tolylamino) phenyl]cyclohexane; N,N'-bis(4-methylphenyl)-N,N'-bis(4~ethylphenyl)- [1 , 1 '-(S.S'-dimethyObiphenylH^'-cliamine; tetrakis-(3-methylphenyl)- N.N.N'.N'^.δ-phenylenediamine; α-phenyl-4-N,N-diphenylaminostyrene; p-(diethylamino)benzaldehyde diphenylhydrazone; triphenylamine; bis[4-(N,N-diethylamino)-2-methylphenyl](4-methylphenyl)methane; 1 -phenyl-3-[p-(diethylamino)styryI]-5-[p-(diethylamino)phenyl] pyrazoline; 1,2-trans-bis(9H-carbazol-9-yl)cyclobutane; N,N,N',N^l-tetrakis(4-methyl- phenyl)-(1,1^l-biphenyl)-4,4'-diamine; N,N'-bis(naphthalen-1-yl)-N,N'-bis- (phenyl)benzidine; porphyrinic compounds, and compounds represented by Formula XVI:

Formula XVI

wherein Ar is an arylene group;

Ar', and Ar" are selected independently from aryl groups; R²⁴ through R²⁷ are selected independently from the group consisting of hydrogen, alkyl, aryl, halogen, hydroxyl, aryloxy, alkoxy, alkenyl, alkynyl, amino, alkylthio, phosphino, silyl, -COR, - COOR, -PO₃R₂, -OPO₃R₂, and CN;

R is selected from the group consisting of hydrogen, alkyl, aryl, alkenyl, alkynyl, and amino; and m and n are integers each independently having a value of from O to 5, where m + n ≠ O.