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Title:
CONDUCTIVE POLYMER COMPOSITIONS EXHIBITING N-TYPE CONDUCTION
Document Type and Number:
WIPO Patent Application WO/2003/087222
Kind Code:
A1
Abstract:
Disclosed are n-type solvent-based conductive polymer compositions comprising at least one conductive polymer, an organic solvent system, at least one dendrimer, and optionally, at least one additive. These conductive polymers exhibit isotropic electronic and/or optoelectronic properties, high conductivity and transmittance, tunable charge mobility and excellent environmental stability. These conductive polymers are suitable for use in a myriad of applications, including electronic and optoelectronic components and devices. Also disclosed are methods, involving a solvent exchange process, for producing these n-type conductive compositions.

Inventors:
Ryu, Jae (160 Indian Hill, Carlisle, MA, 01741, US)
Zhou, Qingye (284 Codman Hill Road, Apt. 21B Boxborough, MA, 01719, US)
Mulfort, Karen (46 Englewood Ave, #5 Brighton, MA, 02135, US)
Application Number:
PCT/US2003/010511
Publication Date:
October 23, 2003
Filing Date:
April 04, 2003
Export Citation:
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Assignee:
ELECON, INC. (200 Turnpike Road, Chelmsford, MA, 01824, US)
Ryu, Jae (160 Indian Hill, Carlisle, MA, 01741, US)
Zhou, Qingye (284 Codman Hill Road, Apt. 21B Boxborough, MA, 01719, US)
Mulfort, Karen (46 Englewood Ave, #5 Brighton, MA, 02135, US)
International Classes:
C08G61/12; C08L65/00; C08L101/00; C08L101/12; C09D201/00; H01B1/12; H01L51/30; (IPC1-7): C08L65/00; C08G61/12; C08L101/00; H01B1/12
Domestic Patent References:
Foreign References:
US6025462A
US6083635A
Other References:
BALOGH ET AL.: "Architectural Copolymers of PAMAM dendrimers and ionic Polyacetylenes" MACROMOLECULES, vol. 32, 3 February 1999 (1999-02-03), pages 1036-1042, XP002245833
TOMALIA ET AL.: "Electrically Conducting Dendrimers" JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol. 119, - 1997 pages 1005-1010, XP002245834
Attorney, Agent or Firm:
Elandjian, Esq. Lucy (Elecon Inc./IP Department, 200 Turnpike Road Chelmsford, MA, 01824, US)
Download PDF:
Claims:
We claim:
1. An organic solvent based ntype conductive polymer composition, comprising: a) at least one aqueous conductive polymer; b) an organic solvent system; c) at least one dendrimer; and d) optionally, at least one additive.
2. An ntype conductive polymer composition according to claim 1, wherein the composition comprises : a) about 0. 1 %about 70% of the at least one aqueous conductive polymer, by weight of the ntype conductive polymer composition; b) about 1 %about 99% of the at least one conductive polymer, by weight of the ntype conductive polymer composition; c) about 0. 1%about 70% of the at least one conductive polymer, by weight of the n type conductive polymer composition; and d) 0%about 20% of the at least one conductive polymer, by weight of the ntype conductive polymer composition.
3. An ntype conductive polymer composition according to claim 1, wherein the at least one aqueous conductive polymer is a substituted polythiophene.
4. An ntype conductive polymer composition according to claim 3, wherein the polythiophene is associated with at least one polyanion.
5. An ntype conductive polymer composition according to claim 4, wherein the polyanion comprises polystyrene sulfonic acid. An ntype conductive polymer composition according to claim 1, wherein the at least one aqueous conductive polymer is poly (3, 4ethylenedioxythiophene)/polystyrenesulfonic acid. An ntype conductive polymer composition according to claim 1, wherein the organic solvent system comprises ethylene glycol, Nmethyl2pyrrolidinone, dimethyl acetamide, or any mixture thereof. An ntype conductive polymer composition according to claim 1, wherein the organic solvent system comprises organic solvents having a boiling point in the range of about 100°C to about 300 °C. An ntype conductive polymer composition according to claim 1, wherein the at least one dendrimer comprises one or more primary, secondary, or tertiary amine. An ntype conductive polymer composition according to claim 1, wherein the at least one dendrimer comprises at least two generations. An ntype conductive polymer composition according to claim 1, wherein the at least one dendrimer comprises two to five generations. An ntype conductive polymer composition according to claim 1, wherein the at least one additive comprises any functionalized alkyl or aromatic sulfonic acid. An ntype conductive polymer composition according to claim 12, wherein the functionalized alkyl and the aromatic sulfonic acid are represented by the following formulas (I) and (II) : and wherein R is any functional groups likeNH3,OH, H,SO3H.
6. 14 An ntype conductive polymer composition according to claim 12, wherein the at least one additive comprises 4hydroxybenzenesulfonic acid.
7. 15 An ntype conductive polymer composition according to claim 1, further comprising at least one extra organic solvent.
8. 16 An ntype conductive polymer composition according to claim 15, wherein the extra organic solvent comprises isopropanol, ethylene alcohol, methyl alcohol, butoxylethenol or any mixture thereof.
9. 17 An ntype conductive polymer composition according to claim 1, wherein the composition exhibits a surface resistivity in the range from about 10 ohms/square to about 10,000 ohms/square.
10. 18 An ntype conductive polymer composition according to claim 17, wherein the composition exhibits a surface resistivity in the range from about 500 ohms/square to about 2,000 ohms/square.
11. 19 An ntype conductive polymer composition according to claim 17 or claim 18, wherein the composition exhibits a uniform surface resistivity along any direction.
12. 20 A coating or film produced from the ntype conductive polymer composition of claim 1 or claim 15.
13. 21 A coating or film according to claim 20, wherein the optical properties of the coating do not deteriorate by more than about 5% when exposed to temperatures in the range from about 50°C to about 200°C, in air at ambient humidity.
14. 22 A coating or film according to claim 20, wherein the optical properties of the coating do not deteriorate by more than about 5% when exposed to humidity in the range from about 10% relative humidity to about 95% relative humidity, in air at ambient temperatures.
15. 23 An article of manufacture comprising the composition of claim 1, or the coating or film of claim 20.
16. 24 An article of manufacture according to claim 23, wherein the article is an organic light emitting device (OLED's), thin film transistor (TFT's), polymer disperse liquid crystal (PDLC), identification tag, battery, catalyst, deicer panel, electrode, electromagnetic shielding, electromechanical actuator, electronic membrane, embedded array antenna, fuel cell, infrared reflector, intelligent material, back light for displays, electrophoretic ink display, electroluminescent display, touch screen display, liquid crystalline display, electrochromic display or window, smart window, toy, supermarket item, solid electrolyte capacitor, polymer electrolyte, radar dish, redox capacitor, sealant, semiconductor circuit, sensor, junction device (PV), printed circuits, solar cells, antiradiation coating, antistatic coating, anticorrosive coating on metal, lithographic resist, noncorrosive paint or ink, conductive ink formulation for ink jet printing of electronic circuitry, nonlinear optical device, conductive paint, telecom device, waveguide, wire (low current), picture tube, silver halide photography, dryplate system, or electrophotography.
17. 25 A method for producing organic solvent based ntype conductive polymers, comprising: a) exchanging the water in an aqueous conductive polymer with an organic solvent system; and b) adding at least one dendrimer, wherein, the dendrimer may be added before, during or after the solvent exchange process.
18. 26 A method for producing organic solvent based ntype conductive polymers according to claim 25, further comprising homogenizing the aqueous conductive polymer, organic solvent system and dendrimer.
19. 27 A method for producing organic solvent based ntype conductive polymers according to claim 25, wherein majority (at least 97%) of the water in the aqueous conductive polymer is removed by the solvent exchange process.
20. 28 A method for producing organic solvent based ntype conductive polymers according to claim 26 or claim 26, further comprising at least one additive.
21. 29 A method for producing organic solvent based ntype conductive polymers according to claim 25, claim 26 or claim 28, wherein the aqueous conductive polymer is a substituted polythiophene.
22. 30 A method for producing organic solvent based ntype conductive polymers according to claim 29, wherein the polythiophene is associated with at least one polyanion.
23. 31 A method for producing organic solvent based ntype conductive polymers according to claim 30, wherein the polyanion comprises polystyrene sulfonic acid.
24. 32 A method for producing organic solvent based ntype conductive polymers according to claim 25, claim 26 or claim 28, wherein the aqueous conductive polymer is poly (3,4 ethylenedioxythiophene)/polystyrenesulfonic acid. A method for producing organic solvent based ntype conductive polymers according to claim 25, claim 26 or claim 28, wherein the at least one additive is 4 hydroxybenzenesulfonic acid. A method for producing organic solvent based ntype conductive polymers according to claim 25, claim 27 or claim 28, further comprising adding at least one extra organic solvent at or after the completion of the solvent exchange process. A method for producing organic solvent based ntype conductive polymers according to claim 34, wherein the at least one extra organic solvent comprises isopropanol, ethylene alcohol, methyl alcohol, butoxylethenol or any mixture thereof. A method for producing organic solvent based ntype conductive polymers, comprising: a) dissolving a dendrimer in an organic solvent system in a reactor while stirring; b) heating the solution to a temperature in the range from about 100°C to about 250°C ; c) contacting the heated organic solvent system with a poly (3,4 ethylenedioxythiophene)/polystyrenesulfonic acid aqueous dispersion; d) homogenizing the dispersion to control the particle size of product; e) replacing the water in the poly (3, 4ethylenedioxythiophene)/polystyrenesulfonic acid aqueous dispersion with the organic solvent system; f) optionally, adding at least one additive before, during or after the solvent exchange process; and g) adding at least one extra organic solvent after the completion of the solvent exchange process, wherein the aqueous dispersion is added into the hot solvent system at a rate of about 0.1 to 1000 ml/minute, and wherein the dendrimer is dissolved before, during or after the addition of the aqueous dispersion.
Description:
CONDUCTIVE POLYMER COMPOSITIONS EXHIBITING N-TYPE CONDUCTION CROSS REFERENCE TO RELATED APPLICATION The present application claims the benefit of and priority to U. S. Provisional Application No. 60/370,754, as filed on April 8,2002.

TECHNICAL FIELD The present invention relates generally to conductive polymer compositions and methods related thereto, and more specifically to environmentally stable n-type conductive polymers that exhibit isotropic charge transport properties and improved coating uniformity. The present invention also relates to methods for producing these n-type conductive polymers, as well as coatings and articles produced therefrom.

BACKGROUND Organic and polymeric conductive or semiconductive materials and devices are receiving more attention recently due to the potential for their use in low cost device manufacturing processes (e. g. , direct patterning). Although intensive research efforts have resulted in significant improvements in material properties, device processing methods and device performances, further improvements in material properties and processes continue to be necessary for commercial scale production.

The majority of conductive polymers exhibit p-type conduction behavior (hole is the majority charge carrier). However, n-type (electron is the majority charge carrier) conductive polymers are also necessary to produce all organic microelectronic devices. Such devices require air-stable films exhibiting isotropic electronic properties. Currently, it is not practical to produce environmentally stable n-type conductive polymers possessing isotropic electronic properties, particularly in film form, due to the long-chain molecular structure and the air- sensitive nature of the polymers. Thus, research efforts have been expended to develop n-type

conductive polymers to improve air sensitivity and isotropic properties; however, only a limited success has been achieved to date.

One approach to address the air-sensitivity problem associated with the existing n-type conductive polymers resulted in the successful fabrication of p-n junctions utilizing n-type polyacetylene. However, these devices were unstable, even under dried helium atmosphere. N- channel Organic Film Effect Transistors (OFET) produced with air stable n-type conductive polymers with substituted metallophthalocyanines have been reported in the art. The n-channel OFET's have to date achieved a field mobility of 0.02 cm2/V. S. Recently, other air stable n-type conductive polymers, such as N-substituted naphthalenetetracarboxylic diimide (NTCDI) derivatives, pentacene, and perylene, have been reported; these polymers have been used to fabricate n-chapel OFETs having a field mobility of up to 1.5 cm2/V. S. However, such OFET's can only be fabricated via a vacuum deposition process that favors a certain type of single crystal structured polymer to achieve useful charge carrier mobility. The vacuum deposition process for fabricating such devices is a very costly procedure.

Typically, most conductive polymers possess relatively linear structures that yield better conductivity along the direction of molecular alignment than in the other directions, and thereby yielding anisotropic electronic and/or optoelectronic properties. The anisotropy of electronic and optoelectronic properties remains a problem for certain applications where uniform electronic properties are crucial.

Much effort has been focused on synthesizing new structures of conductive polymers to solve the anisotropy problems. For example, conjugated hyperbranched polymers have been synthesized to develop three-dimensional structures wherein charge can be transported in all three dimensions. These polymers exhibit improved isotropic properties due to their three- dimensional structures, and can self-assemble into thin films. The morphological, electrical, and optical properties of these films reveal an unexpected high degree of structural order. Similar approaches have resulted in the synthesis of fully conjugated conductive gels, using poly (3- octylthiophene) and conjugated cross-linking reagents.

Dendrimers have also been developed to produce three-dimensional conjugated polymers because they have a perfect three-dimensional structure. Modified poly (amidoamine) dendrimers having anion radical moieties to generate electrically conductive dendrimers have

been synthesized. Other developments in three-dimensional conductive polymers include perflurorinated phenylene. However, the synthesis of three-dimensional conductive polymers directly from the various monomers causes environmental and cost concerns, and it is difficult, if not impossible, to produce commercially practical quantities at present. Further, synthesizing hyperbranched or dendritic conductive polymers is difficult because the materials are not easily processable. The conjugated structure of conductive polymers makes the hyperbranched and dendritic conductive polymers either solvent insoluble or infusible. The modification of such polymers usually increases the cost, reduces the conductivity, and/or negatively impacts other material properties, despite the potential for resolving the solubility problem.

Although the properties of the p-type (p-doped) and neutral poly (ethylenedioxythiophene (PEDOT) are well-known, the properties of the n-doped material are almost unexplored. Only a few papers in the literature have mentioned the n-doping of PEDOT. Polypyrrole typically cannot be n-doped because the injection of the negative charges would require potentials so negative as to be incompatible with the polymer and electrolyte stability. Yet, the smaller band gap of polythiophene allows both p-and n-doping with several salt-solvent combinations having a wide electrochemical stability window, but the n-doped form is still very sensitive to traces of water and oxygen. Improved n-doping at less negative potentials has been achieved by substituting the thiophene monomer in the 3-position with a phenyl group, with ether groups, with alkoxy groups; by introducing an electron withdrawing group to a phenyl-or to an ether- based substituents; or by using 3'-substituted terthiophene. The conjugated structure not only provides a continuous conduction path through the p-orbital overlapping along the polymer backbone, but it also facilitates the generation of charge carriers by either partial oxidation (i. e., p-doping) of the polymer chain with electron acceptors (e. g., 12, AsF5) or partial reduction (i. e., n-doping) with electron donors (e. g. , Na, NH3). However, most n-doped conductive polymers are easily oxidized in the air.

SUMMARY OF THE INVENTION In view of the above, there is a need for n-doped organic solvent soluble conductive polymers. There is also a need for a solvent-based cost-effective method for producing n-doped conductive polymers that exhibit improved isotropic electronic and/or optoelectronic properties.

It is, therefore, an object of the present invention to formulate organic solvent-based n- type conductive polymers.

It is another object of the present invention to formulate organic solvent-based n-type conductive polymers that possess a high charge carrier mobility.

It is another object of the present invention to formulate organic solvent-based n-type conductive polymers that are air-stable.

It is yet another object of the present invention to formulate organic solvent-based n-type conductive polymers that possess three-dimensionally uniform structures and thereby exhibit improved isotropic electronic and/or optoelectronic properties.

It is further object of the present invention to provide a cost-effective method for producing organic solvent-based n-type conductive polymers.

The present invention pertains to organic solvent-based n-type conductive polymers that comprise at least one aqueous conductive polymer, an organic solvent system, at least one dendrimer (a hyperbranched polymer); and optionally, at least one additive. The present invention also pertains to methods for producing such organic solvent-based n-type conductive polymers.

In one embodiment, at least one dendrimer is used to disperse a conductive polymer in an organic solvent system. The dendrimers selected are soluble in organic solvents, such as ethylene glycol (EG), N-methylpyrrolidinone (NMP), or any combination thereof. These dendrimers contain amine functional groups that can adsorb the hydrophilic surfaces of the conductive polymer.

In another embodiment, a commercially available p-type aqueous conductive polymer, Baytron0 P (polyethylenedioxythiophene/polystyrenesulfonate acid), is adsorbed to dendrimers.

BaytronO P typically exhibits anisotropic conductive behavior and contains sulfonic acid groups around particle surfaces, which strongly interacts with amine segments of the dendrimer. After adsorbing conductive polymer particles to its surface and inside its structure, the dendrimer holds these conductive particles and forms an isotropic structure of dendrimer and conductive polymer particle composite, and thereby eliminating the naturally anisotropic structure of the conductive polymer particles. The dendrimer also improves the intermolecular charge transfer properties of the conductive polymer particles.

Other embodiments of the invention comprise third-, fourth-, or fifth-generation dendrimers that contain primary, secondary, tertiary amine and/or hydroxyl groups. The dendrimers used herein are particularly useful in stabilizing dispersions of hydrophilic conductive polymer particles in polar organic solvents, especially NMP, EG, or any combination thereof. While not being bound by theory, it is believed that the amine groups of the dendrimers form ammonium compounds with the sulfonic acid groups of the conductive polymer particles, thus improving the intermolecular charge transfer properties of conductive polymers.

In another embodiment, an additive, such as 4-hydroxybenzenesulfonic acid (HBS), is incorporated into the conductive polymer dispersions. In yet another embodiment, at least one extra solvent, such as isopropanol, ethylene alcohol, methyl alcohol, or butoxylethenol, is added to the conductive polymer dispersion at or after the completion of the solvent exchange process.

The n-type conductive polymer dispersions of the present invention may be utilized to form coatings or films, and they may be utilized in the fabrication of electronic and/or optoelectronic devices. The conductive polymer dispersions containing the dendrimers, with or without additives, yield improved coatings in terms of film uniformity, surface resistance, transparency, adhesion to substrates, and environmental stability.

The above summary of the present invention is not intended to describe each illustrated embodiment or every implementation of the present invention. The figures and the detailed description that follow more particularly exemplify these embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS The invention may be more completely understood in consideration of the following detailed description of various embodiments of the invention in connection with the accompanying drawing, in which: Figure 1 schematically illustrates a dendrimer, according to an embodiment of the present invention; Figure 2 illustrates a polymer composition comprising a dendrimer, a conductive polymer and an additive, according to an embodiment of the present invention;

Figure 3 illustrates a Van der Pauw Hall Measurement worksheet for an n-type conductive polymer (sample number QZ01-129), according to an embodiment of the present invention; Figure 4 illustrates a Van der Pauw Hall Measurement worksheet for a commercially available p-type conductive polymer, Baytron@ P; Figure 5 illustrates the effects of molecular weight of a dendrimer on conductivity of the resulting polymer, according to an embodiment of the present invention; Figure 6 illustrates the TGA spectrum for solids content determination (sample number QZ01-129), according to an embodiment of the present invention; Figure 7 illustrates a UV-vis spectrum of a typical n-type conductive polymer sample, according to an embodiment of the present invention and Figure 8 illustrates a DSC spectrum of a typical n-type conductive polymer sample, according to an embodiment of the present invention.

While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawing and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS As mentioned above, conjugated conductive polymers are attractive for electronic and optoelectronic applications due to their versatility, particularly for use in polymer light emitting diodes (PLEDs), organic transistors, smart windows, electronic paper, antistatic coating, sensors, batteries, solar cells, among others. It is well known that both the degree of s-conjugated extension and the molecular conformation can dramatically affect the optical band gap, which is a crucial property for the application of conjugated polymers. Linear conductive polymers with a high degree of conjugated extension may be obtained by carefully selecting the method of synthesis. The degree of extension can be increased when the conjugation space changes from linear to two-dimensional and/or three-dimensional. The extension of at-conjugation and

molecular conformation affects both the optical band gap and the optoelectronic uniformity of conjugated polymers. Most conjugated polymers are fabricated into devices by spin coating the solutions onto various surfaces or substrates. The electronic properties of linear conductive polymers exhibit anisotropic behavior when the polymers are coated in this manner. The term "anisotropic behavior", as used herein, refers to the dependence of an electrically conductive property or an optical property of the conductive polymer on a particular direction. This can be attributed to the shear orientation of the linear conductive polymer chains during the spin coating process.

Compared to conductive polymers synthesized from conductive monomers, the present invention offers several advantages in material processing and properties. One advantage is the commercial availability of the components, namely the aqueous conductive polymers, preferably, Baytron (D P (polyethelenedioxythiophene/polystyrenesulfonate acid) from Bayer AG (Pittsburg, PA), the dendrimers, preferably DendrepoxTM brand of dendrimers from Epox Ltd.

(Kiryat Shemona 11013, Israel), the additives, such as HBS, and the organic solvents, such as ethylene glycol, and N-methylpyllolidinone which serves to reduce the processing costs.

Another advantage provided by the present invention is the high charge carrier exhibited by the n-type organic solvent-based conductive polymers. Further, the n-type organic solvent-based conductive polymers of the present invention are environmentally stable.

The organic solvent-based n-type conductive polymers of the present invention comprise at least one aqueous conductive polymer, at least one dendrimer, an organic solvent system, and optionally, one or more additives.

The conductive polymers suitable for use herein may be any aqueous conductive polymer, preferably a p-type aqueous conductive polymer. The conductive polymer may be obtained as a colloidal water dispersion. The aqueous conductive polymer may be a polythiophene/anion aqueous dispersion, preferably, a polythiophene/polystyrene sulfonate dispersion, more preferably, a poly 3,4-ethylenedioxythiophene/polystyrene sulfonate aqueous dispersion, even more preferably, an optionally substituted poly-3,4-alkylene dioxythiophene dispersion, and most preferably the dioxythiophene having at least one counter ion. The counter ion is preferably polystyrenesulfonic acid (PSS) and the optionally substituted poly-3,4-alkylene dioxythiophene is preferably poly3, 4-ethylene- dioxythiophene (PEDOT). A preferred example

of such a formulation is the commercially available polyethelenedioxythiophene/ polystyrenesulfonate acid (Baytron (R) P). The solids content of PEDOT/PSS aqueous dispersion is in the range from about 0.8% to about 5%, by weight, and the solids content of Baytron0 P is about 1.2%, by weight.

The n-type conductive polymer compositions of the present invention comprise at least one conductive polymer, from about 0.1% to about 70%, by weight of the resulting polymer dispersion.

Dendrimers suitable for use herein include those that act to switch p-type conductive polymers, such as Baytron0 P to n-type behavior conductive polymers. These dendrimers are soluble in organic solvents, such as ethylene glycol, N-methylpyrrolidinone, or a mixture thereof.

The term"soluble", as used herein, refers to a material capable of being homogeneously distributed in an organic solvent and results in an organic solvent solution or dispersion. These dendrimers contain functional groups that can adsorb the hydrophilic surfaces of the conductive polymer. The term"adsorb", as used herein, refers to the adherence of an atom, ion, or molecule on the surface of another substance by van der Waals force, dipole force, ionic force, or any combination thereof.

In one embodiment, dendrimers are selected to disperse conductive polymer particles in an organic solvent system and to form a dendrimer/conductive polymer composite. The term "dendrimer/conductive polymer composite", as used herein, refers to the adsorption of conductive polymer particles into a dendrimer and the formation of new conductive polymer particles. The dendrimers possess isotropic chemical structures, which benefit the dendrimer/conductive polymer composite by eliminating the anisotropic properties of linear conductive polymers. The general structure of a dendrimer is illustrated in Figure 1.

The dendrimers of the present invention contain one or more primary, secondary, or tertiary amine, in the structure and/or on the surface. The amines are groups are that will react with sulfonic acid groups of a polyanion in an optionally substituted polythiophene and polyanion conductive polymer, such as Baytron0 P, to form ammonium bonds, which connect interaction between conductive particles.

The dendrimers suitable for use herein contain 2 to 10 generations, preferably 2 to 8 generations, more preferably 2 to 6 generations, and most preferably 2 to 5 generations.

Preferably, the dendrimers are obtained as a solution in alcohol. An example of a dendrimer useful herein is the commercially available Dendrepox brand of dendrimers. The Dendrepox dendrimers have molecular weights that range from about 2,500 to about6, 000 g/mol depending on the generation of the dendrimer. The molecular weight is typically used to indicate the dendrimer size rather than the generation of dendrimer. One or more dendrimers may be used for producing the n-type conductive polymers of the present invention. The ratio of dendrimer to polythiophene/polyanion used in the present invention is preferably, between about 0.05 to about 50, more preferably, about 1 to about 20, and most preferably, about 5 to about 10.

The n-type conductive polymer compositions of the present invention comprise at least one dendrimer, from about 0. 1% to about 70%, by weight of the resulting polymer dispersion.

The organic solvent system of the present invention can be any pure solvent or a mixture of two or more organic solvents. Any organic solvent may be useful herein. The preferred organic solvents are ethylene glycol (EG), N-methyl-2-pynolidinone (NMP), dimethyl acetamide (DMAC), a mixture of EG and NMP at any ratio, a mixture of EG and DMAC at any ratio, a mixture of NMP and DMAC at any ratio, and a mixture containing all three solvents (DMAC, NMP and EG) at any ratio. The n-type conductive polymer compositions of the present invention comprise an organic solvent system, from about 1% to about 99%, by weight of the resulting polymer dispersion.

A variety of small molecules, additives, can optionally be added to the polymer dispersion to control particle size and further dope the conductive polymer. The term"additive", as used herein, refers to any small molecule that comprises certain functional groups, such as sulfonic acid, amine and hydroxyl. The small molecule additives can be any chemicals containing any acid groups, preferably sulfonic acid groups, including, but not limited to, benzenesulfonic acid, camphor sulfonic acid and hydroxybenzenesulfonic acid. The preferred additive for use herein is 4-hydroxybenzenesulfonic acid (HBS). The sulfonic acid contained in these additives will dope PEDOT as PSS does while stabilizing the particle size and enhancing adhesion to a substrate. The n-type conductive polymer compositions of the present invention comprise from 0% to about 20%, preferably from about 1 % to about 10 %, by weight, additive.

In one embodiment, the p-type linear conductive polymer particles used herein are randomly adsorbed into the dendrimer molecules. The large aspect ratio of the original

conductive polymer particles no longer exists when a dendrimer/conductive polymer composite is observed as an individual particle, as illustrated in Figure 2. The amine groups of the dendrimer tend to form an ammonium compound with the sulfonic acid groups of the conductive polymer, which then form a charge bridge between the conductive polymer particles as illustrated in Structure A.

Structure A In Structure A, the solid lines represent the connection between any Hydrogen and any Nitrogen, or between any Nitrogen and Carbon contained in the backbone of the dendrimer and thereby fonning primary or secondary or tertiary amino groups; and-SO3-represents the sulfonic acid groups on the conductive polymer particles (not all-SO3-groups in the particle are depicted in Structure A).

The interaction between the-SO3-and the amine groups of the dendrimer improve the isotropic electronic and/or optoelectronic properties of the newly formed dendrimer/conductive polymer composite. The term"isotropic electronic and/or optoelectronic properties", as used herein, refers to a uniform electrically conductive property or optical property of the conductive polymer along any direction. While not being bound by theory, it is believed that the ammonium groups are also essential to switch the p-type linear polythiophene conductive polymer to the n- type polythiophene conductive polymer.

The present invention also provides methods which are compatible with a wide range of commercially available aqueous conductive polymers, to produce electronic and/or optoelectronic n-type conductive polymers. Methods for producing the organic solvent-based n- type conductive polymers of the present invention comprise exchanging the organic solvent system, preferably EG, NMP, or a mixture of the two solvents, for water in an aqueous dispersion of a conductive polymer. In one embodiment, the method comprises adsorption of the aqueous conductive polymer into a dendrimer with vigorous homogenization while an organic

solvent system replaces the water in the conductive polymer dispersion, preferably, the commercially available dispersion Baytrong P. In this method, the water is exchanged for the organic solvent system. The terms"replaced","solvent exchange", or"solvent exchanged", as used herein, refer to the replacement of some or all of the water associated with the polythiophene mixture with the organic solvent system. The following U. S. patents contain additional examples of suitable substituted or unsubstituted thiophene-containing polymers: U. S.

Pat. Nos. 4,731, 408; 4,959, 430; 4,987, 042; 5,035, 926; 5,300, 575; 5,312, 681; 5,354, 613; 5,370, 981; 5,372, 924; 5,391, 472; 5,403, 467; 5,443, 944; 5,463, 056; 5,575, 898; and 5,747, 412; the substituted or unsubstituted thiophene-containing polymers disclosed therein are each incorporated herein by reference.

In another embodiment of the present invention, at least one dendrimer is dissolved in the organic solvent system in a vessel; the organic solvent system is heated in the vessel to a temperature in the range from about 100°C to about 250°C ; the heated organic solvent system is contacted with at least one conductive polymer dispersion, preferably, the poly-3,4 ethylene- dioxythiophene/polystyrene sulfonate aqueous dispersion; and the water removed from the dispersion is replaced or exchanged with the organic solvent system. One or more optional additives may be added at any time before, during, or after the solvent exchange process. The conductive polymer dispersion is added to the surface of the heated organic solvent system at a rate in the range of from about 0.1 to about 1000 mls/minute, preferably from about 0.5 to about 100 mls/minute, more preferably from about 1 to about 10 mls/minute. The contacting step is sufficient to remove at least part of the water from the dispersion as vapor. The resulting polymer composition may be separated from the vessel by filtration, centrifugation, or similar processes.

The sequence of adding additives and dendrimers will affect the properties of the final product. Depending on desired properties of the final product, additives and dendrimers can be added before or after the solvent exchange step. Preferably, the dendrimer is added before the solvent exchange step.

In another embodiment, at least one drying step, preferably after the solvent exchange step, is incorporated. A wide spectrum of drying treatment steps may be suitable for use herein; preferably, such drying treatments facilitate production of compositions having a low surface

resistance. The term"low surface resistance", as used herein, refers to a surface resistance value of a material determined in accordance to ASTM F374, and ranging from about 10 to about 5000 ohms/square for compositions having a thickness in the range from about l Onm to about 300nm, preferably from about 30nm to about 150nm. The drying treatments may also provide resulting polymer compositions with high optical transmission properties, that is, at least about 70%, and preferably, at least about 90%, transmission, at a wavelength in the range of about 300nm and 600nm, when compared with the base aqueous conductive polymer, for example, Baytron@ P.

The n-type conductive polymers resulting from the solvent exchange methods disclosed herein exhibit an improved combination of properties as compared to the aqueous based precursor dispersion.

The n-type conductive polymers of the present invention can be coated onto substrates via any known coating technique, such as spin coating, rod to rod, and dip coating. The substrate material may be metal, glass, ceramic, organic, or other particle. The substrate may be flexible or rigid.

In another embodiment, the properties of the conductive coatings or films produced from the n-type conductive polymers of the present invention are improved with the addition of additives and extra solvents. The term"extra solvent (s) ", as used herein, refers to any organic solvent that will reduce the surface tension of organic solvent based n-type conductive polymer systems, improve the drying properties by lowering the boiling point of the organic solvent system and enhance the adhesion of the n-type conductive polymer coating or film to a substrate.

Extra low boiling point and surface tension organic solvents can particularly improve the coating quality during the coating process. N-type conductive polymers disclosed herein utilize high boiling point organic solvent systems that often require longer drying time and, sometimes, complete drying may be difficult to achieve. For certain applications, for example when quick drying is necessary, the addition of a small amount of extra organic solvent system will accelerate the drying process. Lowered surface tension of organic solvent-based conductive polymers enables the coating of such polymers onto various plastic substrates that have low surface tension. Coating quality and adhesion are, therefore, improved. These extra organic solvents include, but not limited to, ethanol, methanol, butoxyethanol, 2-propanol, butoxylpropanol, acetone, and any mixture thereof. The extra organic solvents can be

incorporated at from about 0.5% to about 80%, by weight, preferably from about 1% to about 50 %, more preferably from about 2% to about 30%, and most preferably, from about 5% to about 20%, by weight, of the resulting by weight of the resulting polymer dispersion.

The coatings and films of the present invention can be used in a variety of thicknesses depending, for example, on intended use, desired transparency, and desired conductivity parameters. A preferred thickness is in the range from about 10nm to about 500nm, a more preferred thickness is in the range from about 50nm to about 300nm. Coatings or films can be produced from the n-type conductive polymers of the present invention, as one or more layers, having a surface resistance in the range from about 10 to about 1012 ohms/square. Preferably, the coatings or films exhibit a surface resistance in the range from about 50 to about 10,000 ohms/square, more preferably, from about 100 to about 4000 ohms/square, most preferably, from about 100 to about 2000 Q/sq. The conductive coatings or films disclosed herein may comprise one or more layers of the n-type conductive polymer.

For some applications, it may be useful to anneal the films and coatings of the present invention to increase electrical conductivity. Annealing can be accomplished via any known method, such as those disclosed in U. S. Pat. No. 6,083, 635.

It is contemplated that the n-type conductive polymer compositions of the present invention may comprise other components, such as fillers, surfactants, organic binders, polymeric binders, crosslinking agents, coupling agents, colorants, inks, dyes, or any combination thereof.

The excellent combination of electric conductivity, high optical transparency, environmental stability and special n-type nature of the coatings derived from the compositions disclosed herein demonstrates that it is an ideal candidate material for many electrical and optoelectronic device applications. Furthermore, low water contents in the solvent exchanged product provide a long lifetime or less performance degradation of the devices fabricated or derived from the n-type conductive compositions of the present invention.

The combination of coatings or films produced from the n-type conductive polymers of the present invention and those produced from the p-type organic solvent-based conductive polymers may replace transparent electrodes of ITO's in certain applications. This unique n-type conductive polymer makes it possible to fulfill all organic material based electro-optic devices,

and thereby significantly reduce manufacturing costs of many electric and optoelectronic devices.

The n-type conductive polymers disclosed herein, and the films and coatings produced therefrom, can be useful in a wide range of applications, including those that require good electrical conductivity. The conductive coatings can be fabricated onto a rigid or flexible substrate, and exhibit high electrical conductivity, high transparency, enhanced adhesion to the substrate, and environmental stability (i. e. , properties do not degrade significantly upon exposure to air or moisture). This coated substrate is subsequently used to fabricate a sub-component or becomes a component of a complex electrical or optoelectronic device. Due to the desirable properties of these coatings, such devices exhibit improved performance and environmental stability relative to devices fabricated from coatings produced from the Baytrong P aqueous dispersion. Examples of such applications, devices, and articles of manufacture include, but are not limited to, organic light emitting devices (OLED's), thin film transistors (TFT's), polymer disperse liquid crystal (PDLC), identification tags such as a smart label adapted for use in consumer goods, battery, catalyst, deicer panel, electrodes, electromagnetic shielding, electromechanical actuator, electronic membrane, embedded array antenna, fuel cell, infrared reflector, intelligent material, back light for displays, electrophoretic ink displays, electroluminescent displays, touch screen displays, liquid crystalline displays, electrochromic displays or windows, smart windows, toy or supermarket item, solid electrolyte capacitors, polymer electrolytes, radar dishes, redox capacitors, sealants, semiconductor circuits, sensors, junction devices (PV), such as photovoltaic cells, the deposition of metals such as copper, nickel, the manufacture of printed circuits, solar cells, the screening of electromagnetic radiation, antiradiation coatings, antistatic coatings, anticorrosive coatings on metals, lithographic resist, non-corrosive paint or ink, conductive ink formulations for ink jet printing of electronic circuitry, non-linear optical device, conductive paint, telecom device, waveguide, wire (low current), leading away electrical charges, for example, in picture tubes, silver halide photography, dry- plate systems, and electrophotography. Preferably, the electromechanical actuator is a biomedical device, a micropositioner, a microsorter, a microtweezer, or a microvalve. Also preferably, the sensor is a biological, a chemical, an electrochemical, an irradiation dosage, a mechanical shock, a temperature, a temperature limit, or a time-temperature sensor.

Examples Having generally described the invention, a more complete understanding thereof can be obtained by reference to the following examples that are provided for purposes of illustration only and do not limit the invention.

The conductive polymer dispersions and coatings, produced in accordance to Examples 1-6, were analyzed and characterized by a variety of methods. The solids content was determined by drying a small portion (about 1 to 3 g) of the polymer dispersion in a small aluminum pan at about 180°C for about 5 hours, and weighing the resulting solid material. The solids content was in the range from about 0.5 to about 3.5% by weight, depending on the formulation. This procedure was repeated at least two times. The solids content was calculated as the average of all solids content determinations. Thermogravimetric analysis (TGA) (TA Instruments, Model 2950) can also be used to determine the solid content (see Figure 6; sample of n-type conductive polymer dispersion produced in accordance to Example 2). Ultraviolet and visible spectrometry (UV-vis) and Differential Scanning Calorimetry (DSC) (TA Instruments Inc., Model 2010) are also used for characterizing the resulting polymer dispersions to confirm resulting polymer dispersion structures, as shown in Figures 7 and 8 (sample of n-type conductive polymer dispersion produced in accordance to Example 2). The viscosity of the resulting polymer dispersions was measured at 20°C with a Digital Viscometer (Brookfield Engineering Labs, Inc. , Middleboro, MA; Model DV-E) and a small sample adapter. The viscosity range of these polymer dispersions ranged from about 30 to about 700 centipoise. The particle size of the polymer dispersions was determined by a light scattering method, utilizing a particle size analyzer (Beckman-Coulter, Miami, FL 33196; Model N4 Plus). The particle size distribution was bimodal, with a small diameter peak in the range of about 30 to about 700 nanometers, and a large diameter peak in the range of about 600 to about 3000 nanometers. The ratio of small particles to large particles varied with the additive type and amount, and the duration and temperature of the reaction.

The electrical properties of the film were determined using four-point probe technique and Hall Effect from Van der Pauw technique. The polymer dispersion was spin-coated onto borosilicate glass wafers at speeds between in the range of about 500 to about 3000 rpm, depending on the desired film thickness. The film was cured at about 130°C for about 5 minutes.

When desired, several layers were added to increase the thickness of the film. Film thickness was measured with a profilometer (Calogic LLC, Fremont, CA; Model Dektak I). The film thickness ranged from about 30 to about 500nm. The surface resistance of the films ranged from about 100 to about 5000 Q/sq utilizing the four-point probe measurement technique. The charge carrier mobility of the films ranged from about 2 to about 10 cm2V~ s~', and the charge carrier density ranged from about IE 19 to about lE20 cm~3.

Volume resistivity of selected coatings were determined more accurately by employing Van der Pauw method for the samples with indium ohmic contacts, or alternatively gold and silver. This method is the most accurate and widely used technique to measure resistivity of thin coatings/films with uniform thickness and irregular shape. By using the same test sample and test set-up with an external magnetic field supply, charge carrier mobility and carrier concentrations were determined by employing the Hall effect measurement technique, in accordance to ASTM F76 (Annual Book of ASTM Standards, Vol. 10.05 (2000), "Standard Test Methods for Measuring Resistivity and Hall Coefficient and Determining Hall Mobility in Single-Crystal Semiconductors").

A result of Van der Pauw/Hall measurement of the coatings is shown in Figure 3 (for Example 2). This coating was prepared by first performing the solvent exchange method using the aqueous dispersion Baytrong P and an organic solvent system comprised of ethylene glycol and dendrimer. This particular coating, prepared by spin-coating the polymer dispersion onto a glass substrate, exhibited very high electron (negative charge carrier) mobility of 4.85 Cm2/V. S.

Where the result of Hall voltages is a negative number, it illustrates the n-type nature of the conductive polymer produced from this process, as compared to a positive Hall voltages number that illustrates the p-type nature of that conductive polymer. Van der Pauw technique Hall effect measurements also demonstrated that the coating formed from the dendrimer/conductive polymer composite exhibits isotropic conductivity.

Example 1: 200 ml ethylene glycol was added to a four-neck 1000 ml round bottom flask equipped with a nitrogen inlet, a Dean Stark trap and condenser (with nitrogen outlet and attached to a water chiller), a homogenizer (IKA-Works, Inc. , Wilmington, NC; T-25 basic homogenizer with

a 19 mm diameter dispersing tool), and a feed tube inlet driven by a peristaltic pump. The reactor flask was placed in a stirring silicon oil bath and allowed to reach a temperature of 120°C. The oil temperature was controlled with a thermometer and a temperature controller. A nitrogen flow of about 8-10 standard liters per minute was maintained throughout the reaction.

Before use, the dendrimer was diluted from about 5 percent to about 30 percent, by weight, of the original concentration in the desired solvent in order to facilitate diffusion into the conductive polymer and organic solvent solution. 1 ml of a solution of IB-100 (Dendrepox brand of dendrimer; a product of Epox Ltd. , Kiriat Shmona, Israel; molecular weight 6,500 g/mol, H- functionality size 30/mole) in ethylene glycol (density = 1.13g/ml, 25% solids by weight) was added to the reactor flask with homogenizing speed at about 20,000 rpm. The solution was homogenized for about 10 minutes, then 150 ml Baytron0 P (as received from Bayer AG) in a graduated cylinder was added in a drop-wise fashion to the reactor flask using a peristaltic pump at a rate of about 2.1 ml/min. During this addition step, liquid (mostly water from Baytron@ P) vaporized and condensed, and then collected in the Dean Stark trap. When approximately 150 ml liquid was collected, the reactor was removed from the hot oil bath and allowed to homogenize for another 10-15 minutes. The homogenizing was then stopped, and the resulting dispersion was allowed to cool to room temperature. The volume of the dispersion and the liquid collected was recorded.

The resulting polymer dispersion containing about 10 weight percent IB-100, exhibited n- type behavior as demonstrated by the Hall Effect measurements taken from film produced by spin-coating the polymer onto borosilicate glass wafers. The surface resistance of the polymer, measured with the four-point probe technique, ranged from about 600 to about 10000 Q/square, depending on film thickness. The characterization data is presented in Table I.

Table I. Properties of coatings prepared from n-type conductive polymers containing IB- 100 dendrimer EG : NMP (v/v) Properties 100: 0 80 : 20 50 : 50 0 : 100 Solid content (wt%) 0. 96 1. 10 l. ll 1. 66 Viscosity (cp, 20C) 367 290 148 76 Layers at 2000 rpm 1 1 1 2 Drying temp (C) 100 100 100 100 % transmission 85. 4 88. 1 88. 5 86. 8 Film thickness (nm) 70 50 50 40 Surface resistance (kohm/sq) 1. 80 3.50 4. 50 8. 45 Bulk conductivity (S/cm) 79. 4 57. 1 44. 4 29. 6

Example 2: The procedure detailed in Example 1 was followed; however, in this example a 1 ml of a solution of HB-101 (a D endrepox Tm brand of dendrimer ; a product of Epox Ltd.; molecular weight 8,300g/mole, H-functionality 30/mole) in ethylene glycol (density = 1. OOg/ml, 23% solids by weight was added to the reactor flask with homogenizing speed at about 20,000 rpm.

The resulting polymer dispersion, containing about 10 weight percent HB-101, exhibited n-type behavior as demonstrated by the Hall Effect measurements taken from film produced by spin-coating the polymer onto borosilicate glass wafers. The surface resistance of the polymer, measured with the four-point probe technique, ranged from about 400 to about 8000 #/square, depending on film thickness. The characterization data is presented in Table II.

Table II. Properties of coatings prepared from n-type conductive polymers containing HB-101 dendrimer EG: NMP (v/v) Properties 100: 0 Solid content (wt%) 0. 90 Viscosity (cp, 20C) 277 Layers at 2000 rpm 2 Drying temp (C) 100 % transmission 86. 1 Film thickness (nm) 55 Surface resistance (kohm/sq) 1.75 Bulk conductivity (S/cm) 103.9

Example 3 : The procedure detailed in Example 1 was followed; however, in this example a 3 ml of a solution of AD-102 (a Dendrepox brand of dendrimer ; molecular weight 12,100, H- functionality 45/mole) in ethylene glycol (density = 1. Olg/ml, 12% solids by weight) was added to the reactor flask with homogenizing speed at about 20,000 rpm. AD-102 was diluted in NMP, due to its lower solubility in alcohol.

The resulting polymer dispersion, containing about 10 weight percent AD-102, exhibited n-type behavior as demonstrated by the Hall Effect measurements taken from film produced by spin-coating the polymer onto borosilicate glass wafers. The conductivity and other properties of the polymer dispersion, including surface resistance (ranged from about 500 to about 5000 Q/sq, depending the thickness of the film) transmittance, film thickness, and solids content were determined. The characterization data is presented in Table III.

Table III. Properties of coatings prepared from n-type conductive polymers containing AD-103 dendrimer EG: NMP (v/v) Properties 100: 0 97 : 3 Solid content (wt%) 0. 95 0. 99 Viscosity (cp, 20C) 442 413 Layers at 2000 rpm 2 1 Drying temp (C) 100 100 % transmission 87.6 87.2 Film thickness (nm) 30 45 Surface resistance (kohm/sq) 2.90 2. 12 Bulk conductivity (S/cm) 114. 9 104. 8

Example 4: The procedure detailed in Example 1 was followed; however, in this example a 1 ml of a solution of 30% IB-100 (a Dendrepox brand of dendrimer) in ethylene glycol (density = 1. 13g/ml, 23% solids by weight) was added to the reactor flask with homogenizing speed at about 20,000 rpm. And, O. lg 4-hydroxybenzenesulfonic acid (HBS) was added to the reactor near the end of the reaction when the reaction was about 90 to 95% complete (when about 135- 140 ml liquid was collected). The solvent exchange was allowed to complete as in Example 1, and the procedure was continued as detailed in Example 1.

The resulting polymer dispersion, containing about 10 percent, by weight, IB-100 and 5 percent, by weight, HBS, exhibited n-type behavior as demonstrated by the Hall Effect measurements taken from film produced by spin-coating the polymer onto borosilicate glass wafers. The incorporation of HBS improved the coating uniformity of the film without detracting from the polymer's other properties. The surface resistance of the polymer, measured with the four-point probe technique, ranged from about 500 to about 5000 Q/sq, depending on film thickness. The characterization data is presented in Table IV.

Table IV. Properties of coatings prepared from n-type conductive polymers containing IB- 100 dendrimer and additive HBS (5 %) EG: NMP (v/v) Properties 100: 0 80 : 20 Solid content (wt%) 0. 91 1. 19 Viscosity (cp, 20C) 424 381 Layers at 2000 rpm 2 1 Drying temp (C) 100 100 % transmission 86.5 87.9 Film thickness (nm) 80 70 Surface resistance (kolun/sq) 1.73 2.95 Bulk conductivity (S/cm) 72. 3 48. 4

Example 5: As outlined in Examples 1-4, several n-type conductive polymers were prepared utilizing various dendrimers. The resulting polymer dispersion, containing about 10 percent, by weight, IB-100 and 10 percent, by weight, HBS, exhibited n-type behavior as demonstrated by the Hall Effect measurements taken from film produced by spin-coating the polymer onto borosilicate glass wafers. The effects of the molecular weight of the dendrimers and the additive HBS on the coating properties of n-type conductive polymers are summarized in Table V and Table VI.

Increasing the molecular weight of dendrimer from about 2,500 g/mol. to about 16,000 g/mol. resulted in an increase in conductivity from about 80 S/cm to about 120 S/cm. The polymers were coated onto glass or PET substrate and dried for about 5 minutes at 100°C or 130°C, depending on the substrate. The organic solvent used in the preparation of the polymer dispersion was 100% ethylene glycol. The characterization data is presented in Table V (for glass substrate) and Table VI (for PET substrate).

Table V. Properties of coatings prepared from n-type conductive polymers containing IB- 100 dendrimer and additive HBS (10 %) Additive Properties IB-100 HB-101 AD-102 IB-100 + HBS Dendrimer molecular weight (g/mol) 6500 8300 12,100 6500 Solid content (wt%) 0. 96 0. 90 0. 95 0. 91 Viscosity (cp, 20C) 367 277 442 424 Layers at 2000 rpm 1 2 1 2 Drying temp (C) 100 100 100 100 % transmission 85 4 86. 1 87. 6 86. 5 Film thickness (nm) 70 55 30 80 Surface resistance (kohm/sq) 1.80 1. 75 2. 90 1. 73 Bulk conductivity (S/cm) 79.4 103. 9 114.9 72.3

Table VI. Data of coatings from Table V on PET substrates containing different dendrimers (at 10% solids) and HBS (at 10% solids) Additive Properties IB-100 HB-101 AD-102 IB-100 + HBS Layers at 2000 rpm 1 2 1 2 Drying temp (C) 130 130 130 130 % transmission 86. 0 86. 0 84. 8 85. 4 Surface resistance (kohm/sq) 2. 00 1. 70 1. 43 1. 79

Example 6: As outlined in Examples 1-4, several n-type conductive polymers were prepared utilizing various dendrimers. These polymers were prepared for environmental stability by spin coating onto 2-inch diameter fused quartz substrates at 2000 rpm speed, followed by drying at 130°C for 5 minutes using a hot plate in air. Three different samples were fabricated using three different types of conductive polymers: (1) Eleflex Tm 2300 (product of Elecon, Inc. , Chelmsford, MA) is a p-type PEDOT: PSS based conductive polymer system produced via a solvent exchange process where the water is exchanged with the organic solvent system; it has a very low water content, at less than 3% water by weight; (2) n-type conductive polymers of the present invention; and (3)

commercially available aqueous conductive polymer system, Baytron P. Surface resistance of the samples, as coated, was measured by employing a standard four-point probe method (Step I).

Immediately after measuring the surface resistance, samples were placed in an oven at 200°C for 2 hours. The samples were removed from the oven and then cooled to room temperatures in 30 minutes. The surface resistance of each sample was re-measured immediately. As shown in the Step II of Table VII, the surface resistance of the coatings produced from the p-type and the n- type conductive polymers did not change significantly after heating at 200°C, whereas the surface resistance of the coating produced from the aqueous BaytronX P decreased by about 23 percent.

The samples were stored at ambient temperatures for 24 hours, then, they were placed in a 97% relative humidity (calcium sulfate salt) chamber at ambient temperatures for 24 hours.

The surface resistance, at ambient temperatures and humidity, of each sample was re-measured.

As shown in the Step III, the surface resistance of the coatings produced from the p-type and n- type conductive polymers did not change; but the surface resistance of the coating produced from Baytront P decreased further by about 27 percent (44 percent in total). Results of this test clearly demonstrate, with respect to temperature, air and humidity, the environmental stability of the coatings produced from n-type conductive polymers of the present invention. The results of the environmental stability tests are presented in Table VII.

TABLE VII. Environmental Stability Test Results Surface Resistance (Kohm/sq.) Sequential Environmental P-type Conductive N-type Conductive Baytrong P Steps Conditions Polymer Polymer Conductive Polymer I As Coated 1.32 1. 35 150 Exposure to 200°C II for 2 hours 1.29 1. 3 115 24 hours at 98% RH 1.32 1. 31 83. 7