HK1108059A - Transparent polymeric electrode for electro-optical structures - Google Patents

Description

Transparent polymer electrodes for photovoltaic construction

Technical Field

The invention relates to a method for producing transparent multilayer electrodes from electrically conductive polymers, to the electrodes produced by this method, and to the use thereof in optoelectronic structures.

Background

Displays based on Organic Light Emitting Diodes (OLEDs) are an alternative to existing Liquid Crystal (LCD) technology due to their special properties. This new technology provides advantages particularly for applications involving portable devices that do not have access to mains power, such as mobile telephones, pagers and toys.

The benefits of OLEDs include extremely planar designs, the ability to produce their own light characteristics, which means that they do not require additional light sources, as do Liquid Crystal Displays (LCDs), high luminous efficiency, and unlimited viewing angles.

However, besides displays, OLEDs can also be used for illumination, for example in large-area radiant emitters. Due to their extremely planar design, they can be used to produce very thin lighting elements, which has not been achieved to date. The luminous efficiency of OLEDs is nowadays well beyond that of thermal radiation emitters, such as incandescent bulbs, and their emission spectrum can be varied substantially as desired by the choice of suitable luminescent materials.

Neither OLED displays nor OLED lighting elements are limited to planar rigid designs. Due to the flexibility of the organic functional layer, a flexible or curved arrangement can be achieved in any way.

The organic light emitting diode has an advantage in its simple configuration. This configuration is generally as follows: the transparent electrode is applied to a transparent support, for example glass or plastic film. Above this, at least one organic layer (light-emitting layer) or a stack of sequentially applied organic layers is arranged. Finally, a metal electrode is added.

The structure of Organic Solar Cells (OSCs) is substantially the same (Hall et al, Nature 1995, 376, 498), except that light is instead converted into electrical energy.

The economic success of these new photovoltaic constructions depends not only on the fulfillment of the technical needs, but also mainly on the production costs thereof. The simplified process steps result in reduced production complexity and thus production costs become of paramount importance.

TCO (transparent conductive oxide) layers such as Indium Tin Oxide (ITO) or Antimony Tin Oxide (ATO) or thin metal layers have hitherto generally been used as transparent electrodes in OLEDs or OSCs. The precipitation of these inorganic layers is carried out by sputtering, reactive surface atomization (reactive sputtering) or thermal evaporation processes of organic materials in vacuum and is therefore complicated and cost-intensive.

The ITO layer is an important cost factor in the production of OLEDs or OSCs. ITO layers are used because they combine high conductivity with high transparency. However, ITO has several disadvantages:

a) ITO can only be deposited (by reactive sputtering) in a complex, cost-intensive vacuum process.

b) If high conductivity is to be achieved, temperatures of T > 400 ℃ are required during the deposition. Especially polymer substrates, which are important for flexible displays, cannot withstand such temperatures.

c) ITO is brittle and tends to form cracks when molded.

d) Indium metal is a raw material with a very limited yield, and a supply shortage is expected if the consumption is further increased.

e) How to deal with a photoelectric structure containing heavy metal indium in coordination with the environment is an unsolved problem.

Despite these disadvantages, ITO layers are still in use because of their better conductivity to light absorption ratios, and most importantly, there is no suitable alternative. The high conductivity is required to suppress the voltage drop between the transparent electrodes in the current driving structure.

A replacement for ITO has been discussed in the past as an electrode material, but to date no replacement has been found which does not suffer from the above-mentioned disadvantages and which at the same time has better properties in photovoltaic structures.

Thus, there has been described a polymeric ITO alternative to polymerising monomers in situ on a substrate to form a conductive layer, for example, poly (3, 4-ethylenedioxy) thiophene polymerised in situ, which is also referred to by the expert as in situ PEDT (WO-A96/08047). However, in addition to possibly being difficult to handle on the substrate, these in-situ PEDT layers have some drawbacks, in particular for applications in OLEDs, firstly the material has a very deep intrinsic color and secondly the electroluminescent efficiency that can be achieved with it is low.

Furthermore, complexes of polyethylenedioxythiophene and polystyrenesulfonic acid, abbreviated to PEDT/PSA or PEDT: PSA by the expert, have been proposed as alternatives to the polymer ITO (EP-A686662, Ingan Kaps et al, adv. Mater.2002, 14, 662-. However, the conductivity of PEDT: PSA layers made from formulations having a PEDT: PSA ratio of, for example, 1: 2.5 (weight percent) is not particularly high, e.g., aqueous dispersions of PEDT/PSA (Baytron)^®Starck) of about 0.1S/cm, far less than the desired value for ITO of 5000 to 10000S/cm. Although the conductivity can be increased to about 50S/cm by adding additives such as dimethyl sulfoxide, N-methylpyrrolidone, sorbitol, ethylene glycol or glycerol to such aqueous PEDT/PSA dispersions, it is still much lower than the value for ITO. Moreover, due to their coarse-grained structure, these formulations result in relatively coarse layer surfaces, which is a controversial point for using these layers as a substitute for ITO in many photovoltaic applications. These layers are not very suitable, especially in applications that are sensitive to short circuits due to surface roughness, such as OLEDs and OSCs.

There is therefore still a need for a suitable ITO replacement material which does not have the disadvantages of ITO while having equivalent electrical properties or optoelectronic structures.

Disclosure of Invention

It is therefore an object of the present invention to produce an electrode which can replace conventional ITO electrodes but which does not have the above-mentioned disadvantages.

It has surprisingly been found that an electrode consisting of at least two electrode layers, wherein a first electrode layer is made of a 50 wt.% polythiophene dispersion of particles smaller than 50nm, which is applied to a second layer comprising a hole injection material, is able to meet these needs.

The invention thus provides a method for manufacturing an electrode comprising at least two layers, characterized in that:

the first layer is prepared by applying a dispersion comprising at least one polymer anion and at least one optionally substituted polythiophene comprising recurring units of the general formula (I) on a suitable substrate,

wherein

A represents optionally substituted C₁To C₅Alkylene, preferably optionally substituted C₂To C₃An alkylene group or a substituted alkylene group,

r represents a linear or branched, optionally substituted C₁To C₁₈Alkyl, optionally substituted C₅To C₁₂Cycloalkyl, optionally substituted C₆To C₁₄Aryl, optionally substituted C₇To C₁₈Aralkyl, optionally substituted C₁To C₄A hydroxyalkyl group or a hydroxyl group,

x represents an integer of 0 to 8, preferably 0 or 1, and

if several radicals R are attached to A, they may be identical or different,

50 wt.% of the particles in the dispersion are smaller than 50nm, then allowed to solidify, and then

The second layer is prepared by applying at least one organic hole injection material and optionally at least one anion (made from a solution or dispersion by physical vapour deposition) onto the first layer and then optionally curing it.

The general formula (I) is understood to mean that x substituents R can be attached to the alkylene radical A.

Polythiophenes comprising recurring units of the formula (I) are preferably examples comprising recurring units of the formula (Ia):

wherein

R and x have the meanings given above.

Polythiophenes are particularly preferred examples which contain recurring units of the general formula (Iaa):

in a preferred embodiment according to the invention, polythiophenes are examples which are composed of recurring units of the formula (I), preferably of the formula (Ia), particularly preferably of the formula (Iaa).

Within the meaning of the present invention, the prefix poly is understood to mean that more than one identical or different repeating unit is comprised in the polymer or polythiophene. The polythiophenes comprise a total of n recurring units of the formula (I), where n is in particular an integer from 2 to 2000, preferably from 2 to 100. The recurring units of the formula (I) in the polythiophenes can be identical or different. Preferred polythiophenes have identical recurring units of the formula (I), preferably of the formula (Ia), particularly preferably of the formula (Iaa).

Preferably, the end groups of the polythiophenes each carry H.

In a particularly preferred embodiment, the polythiophene having a repeating unit of the general formula (I) is poly (3, 4-ethylenedioxythiophene), i.e. a homopolythiophene composed of repeating units of the general formula (Iaa).

The dispersion used to make the first layer preferably has 50 wt.% of the particles therein less than 40nm, preferably less than 30 nm.

Particle size distribution can be determined by analytical ultracentrifuges, such as h.g. muller; progr, colloid Polymer, Sci.127(2004) 9-13.

It is particularly preferred to add to the dispersion used for the manufacture of the first layer one or more additives which improve the electrical conductivity, for example compounds containing ether groups such as tetrahydrofuran, compounds containing lactone groups such as gamma-butyrolactone, gamma-valerolactone, compounds containing amide or lactam groups such as caprolactam, N-methylcaprolactam, N-dimethylacetamide, N-methylacetamide, N-Dimethylformamide (DMF), N-methylformamide, N-methylformanilide, N-methylpyrrolidone (NMP), N-octylpyrrolidone, pyrrolidone, sulfones and sulfoxides such as sulfolane (tetramethylene sulfone), dimethyl sulfoxide (DMSO), sugars or sugar derivatives such as sucrose, glucose, fructose, lactose, sugar alcohols such as sorbitol, mannitol, furan derivatives such as 2-furancarboxylic acid, 3-furancarboxylic acid, and/or diols or polyols, such as ethylene glycol, glycerol, diethylene glycol or triethylene glycol. Tetrahydrofuran, N-methylformamide, N-methylpyrrolidone, dimethyl sulfoxide or sorbitol are preferably used as conductivity-increasing additives. Dimethyl sulfoxide is particularly preferred. The additives are preferably added to the dispersion for producing the first layer in an amount of at least 0.1% by weight, preferably at least 0.5% by weight, particularly preferably at least 1% by weight, based on the total weight of the dispersion.

The organic injection material may be a polymer or a low molecular weight material, the latter also known in the industry as a small molecule material. Suitable examples of polymeric hole injection materials include polythiophenes, polyaniline-based compounds, such as polyaniline/camphorsulfonic acid (PANI-CSA) (g. gustafsson et al, Nature357(1992)477), polyaniline-based compounds, such as poly (aryl ether sulfone) (PTPDES: TBPAH) (a. fukase et al, polymer.adv. technol.13(2002)601) or poly (2, 7- (9, 9-di-n-octylfluorene) -alt- (1, 4-phenylene- ((4-sec-butylphenyl imino) -1, 4-phenylene)) (TFB) (j.s.kim et al, appl.phys.lett.87(2005)23506), fluorinated polymers (l.s.huhu, appl.phys.lett.78 (672001) 673) and mixtures of these compounds.

Preferred polymers, hole-injecting materials are optionally substituted polythiophenes which contain recurring units of the general formulae (II-a) and/or (II-b),

wherein

A represents optionally substituted C₁To C₅Alkylene, preferably optionally substituted C₂To C₃An alkylene group or a substituted alkylene group,

y represents O or S, and Y represents O or S,

r represents a linear or branched, optionally substituted C₁To C₁₈Alkyl, optionally substituted C₅To C₁₂Cycloalkyl, optionally substituted C₆To C₁₄Aryl, optionally substituted C₇To C₁₈Aralkyl, optionally substituted C₁To C₄A hydroxyalkyl group or a hydroxyl group,

x represents an integer of 0 to 8, preferably 0 or 1,

if several radicals R are attached to A, they may be identical or different,

and may optionally further comprise at least one polymeric anion.

Polythiophenes which comprise recurring units of the formula (II-a) are preferably examples which comprise recurring units of the formulae (II-a-1) and/or (II-a-2),

wherein

R and x have the meanings given above.

Particularly preferred are polythiophenes which contain recurring units of the general formulae (II-aa-1) and/or (II-aa-2).

In a particularly preferred embodiment, the polythiophenes having recurring units of the general formulae (II-a) and/or (H-b) are poly (3, 4-ethylenedioxythiophene), poly (3, 4-ethylenedioxythiothiophene) or poly (thieno [3, 4-b ] thiophene), in other words homopolythiophenes composed of recurring units of the general formulae (II-aa-1), (II-aa-2) and/or (II-b).

In a further particularly preferred embodiment, the polythiophenes having recurring units of the formulae (II-a) and/or (II-b) are copolymers composed of recurring units of the formulae (II-aa-1) and (II-aa-2), (II-aa-1) and (II-b), (II-aa-2) and (II-b) or (II-aa-1), (II-aa-2) and (II-b), preferably copolymers composed of recurring units of the formulae (II-aa-1) and (II-aa-2) and (II-aa-1) and (II-aa-b).

Within the meaning of the invention, C₁To C₅Alkylene A of (A) is: methylene, ethylene, n-propylene, n-butylene or n-pentylene. C within the meaning of the invention₁To C₁₈Alkyl denotes straight-chain or branched alkyl, for example methyl, ethyl, n-or i-propyl, n-, i-, s-or t-butyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 1-ethylpropyl, 1-dimethylpropyl, 1, 2-dimethylpropyl, 2-dimethylpropyl, n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-hexadecyl or n-octadecyl, C₅To C₁₂Cycloalkyl radicals, e.g. cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl or cyclodecyl, C₆To C₁₄Aryl radicals, e.g. phenyl or naphthyl, C₇To C₁₈Aralkyl radicals are, for example, benzyl, o-, m-, p-tolyl, 2, 3-, 2, 4-, 2, 5-, 2, 6-, 3, 4-, 3, 5-xylyl or mesityl. For use in the above listThe present invention is illustrated by way of example and should not be construed as exhaustive.

A number of organic radicals are suitable as C₁To C₅Optional further substituents of alkylene groups a, for example alkyl, cycloalkyl, aryl, halogen, ether, thioether, disulfide, sulfoxide, sulfone, sulfonic acid, amino, aldehyde, ketone, carboxylic acid ester, carboxylic acid, carbonic acid group, carboxylic acid group, cyano, alkylsilane and alkoxysilyl groups, and carboxamido groups.

Preferred polymeric anions are, for example, polymeric carboxylic anions, such as polyacrylic acid, polymethacrylic acid or polymaleic acid, or polysulfonic acids, such as polystyrenesulfonic acid and polyvinylsulfonic acid. These polycarboxylic or polysulfonic acids may also be copolymers of vinylcarboxylic and vinylsulfonic acids with other polymerizable monomers, such as acrylates and styrene.

Particularly preferred as copolymer anion is the Polystyrene Sulfonic Acid (PSA) anion as the counter ion.

In addition to the above, containing SO₃ ^-M⁺Or COO^-M⁺Partially fluorinated or perfluorinated polymers of the group are also suitable for use as polymer anions for the second electrode layer, in particular in combination with polythiophenes comprising recurring units of the general formulae (II-a) and/or (II-b). This contains SO₃ ^-M⁺Or COO^-M⁺The partially or perfluorinated polymer of the group may be, for example, Nafion, which is commercially available^®. Polystyrene Sulfonic Acid (PSA) anion and Nafion^®Mixtures of (a) are also suitable as polymer anions for the second electrode layer.

The molecular weight of the polymeric acid delivering the polymeric anion is preferably from 1000 to 2,000,000, particularly preferably from 2000 to 500,000. Polymeric acids or their basic salts are commercially available, for example polystyrenesulfonic acids and polyacrylic acids, or can be obtained by known methods (see, for example, Houben Weyl, Methoden der organischen Chemie, Vol. E20 Makromolekulare Stoffe, Part 2(1987), p.1141 ff.).

The polythiophenes can be neutral or positive. In a preferred embodiment, it is positive, "positive" refers only to the charge located on the polythiophene backbone. Depending on the substituents on the radical R, the structural units of the polythiophenes can have a positive charge or a negative charge, the positive charge being located on the polythiophene main chain and the negative charge optionally being located on the radical R which is substituted by sulfonic acid or carboxylic acid groups. In this case, the positive charge on the polythiophene main chain can be partially or completely saturated with anionic groups optionally present on the radical R. The polythiophenes in these cases may be positive, neutral or even negative, considered as a whole. However, within the meaning of the present invention, they are all considered to be positive polythiophenes, since the positive charge on the polythiophene main chain is decisive. The positive charge is not shown in the formula because its exact number and position cannot be determined. However, the number of positive charges is at least 1 and at most n, n being the total number of all repeating units (identical or different) within the polythiophene.

In order to counteract the positive charge, the positive polythiophenes require an anion as a counterion if the optionally sulfonic or carboxylic acid-substituted, and thus negatively charged, radicals R are not sufficient to counteract.

The counter ion may be a monomeric or polymeric anion, the latter also referred to hereinafter as a polyanion.

The polymeric anions may be those already listed above. Suitable monomeric anions are, for example, C₁To C₂₀Paraffin sulfonic acids, such as methane, ethane, propane, butane or higher sulfonic acids, such as dodecyl sulfonic acid; aliphatic perfluorosulfonic acids such as trifluoromethanesulfonic acid, perfluorobutanesulfonic acid or perfluorooctanesulfonic acid; aliphatic C₁To C₂₀Carboxylic acids such as 2-ethylhexyl carboxylic acid; aliphatic perfluorocarboxylic acids such as trifluoroacetic acid or perfluorooctanoic acid; quilt C₁To C₂₀Alkyl-substituted aromatic sulfonic acids such as benzenesulfonic acid, o-toluenesulfonic acid, p-toluenesulfonic acid or dodecylbenzenesulfonic acid; and cycloalkylsulfonic acids, e.g. camphorsulfonic acid or tetrafluoroborate, hexafluorophosphatePerchlorate, hexafluoroantimonate, hexafluoroarsenate or hexachloroantimonate.

Particular preference is given to the anion of p-toluenesulfonic acid, methanesulfonic acid or camphorsulfonic acid.

Cationic polythiophenes which contain anions as counterions to counteract the charge are also commonly referred to by the expert as polythiophene/(poly) anion complexes.

In the layer containing at least one polymer anion and at least one polythiophene having a repeating unit of the general formula (I) or (II-a) and/or (II-b), the polymer anion can be used as a counter ion. However, other counterions may also be present in this layer. Preferably, however, polymer anions are used as counter-ions in the layer.

The weight ratio of polymer anion and polythiophene comprised in the first layer may be from 0.5: 1 to 20: 1, preferably from 1: 1 to 5: 1. The weight ratio of polymer anions and polythiophenes contained in the second layer can be from 0.5: 1 to 50: 1, preferably from 1: 1 to 30: 1, particularly preferably from 2: 1 to 20: 1. The weight of polythiophenes here corresponds to the weight of the monomers used, assuming complete conversion has taken place during the polymerization.

In a preferred embodiment, the first layer is made of a dispersion containing a polyanion and a polythiophene having a repeating unit of the general formula (I), wherein R, A and x have the meaning given above, and the second layer is applied to the first layer, which consists of a dispersion containing a polymer anion and a polythiophene having a repeating unit of the general formula (II-a) and/or (II-b).

In a most preferred embodiment, the first layer is made of a dispersion containing polystyrene sulfonic acid and poly (3, 4-ethylenedioxythiophene), onto which the second layer is applied, made of a dispersion containing polystyrene sulfonic acid and poly (3, 4-ethylenedioxythiophene), also known in the industry as PEDT/PSA or PEDT: PSA.

Both dispersions (used to make the first and second electrode layers) may also contain one or more solvents. Examples of suitable solvents are aliphatic alcohols such as methanol, ethanol, isopropanol and butanol, aliphatic ketones such as acetone and methyl ethyl ketone, aliphatic carboxylic acid esters such as ethyl acetate and butyl acetate, aromatic hydrocarbons such as toluene and xylene; aliphatic hydrocarbons, such as hexane, heptane and cyclohexane, chlorinated hydrocarbons, such as dichloromethane and dichloroethane, aliphatic nitriles, such as acetonitrile, aliphatic sulfoxides and sulfones, such as dimethyl sulfoxide and sulfone, aliphatic carboxylic acid amides, such as methylacetamide, dimethylacetamide and dimethylformamide, aliphatic and aromatic aliphatic ethers, such as diethyl ether and anisole. Water or mixtures of water with the above-mentioned organic solvents may also be used as solvents. Preferred solvents are water or other protic solvents such as alcohols, for example methanol, ethanol, isopropanol and butanol, and also mixtures of water with these alcohols; a particularly preferred solvent is water.

If the dispersions contain one or more solvents, the solids content of these dispersions is preferably from 0.01 to 20%, particularly preferably from 0.1 to 10%, based on the total weight of the dispersion.

The dispersion used for the manufacture of the first electrode layer preferably has a viscosity of 5 to 300mPas, preferably 10 to 100 mPas. The dispersion used for manufacturing the second electrode layer preferably has a viscosity of 2 to 300mPas, preferably 5 to 100 mPas.

The solution viscosity measured here was measured using a Haake RV 1 rheometer with a thermostat. 13.5 g. + -. 0.3g of the solution to be measured are weighed into a clean and dry measuring cup, placed in a measuring slit and kept at 20.0 ℃ for 100s^-1Is measured at a shear rate of (c).

Other ingredients may also be added to the dispersion used to make the second electrode layer, for example one or more organic binders soluble in organic solvents, for example polyvinyl acetate, polycarbonate, polyvinyl butyral, polyacrylate, polymethacrylate, polystyrene, polyacrylonitrile, polyvinyl chloride, polybutadiene, polyisoprene, polyethers, polyesters, silicones, styrene/acrylates, vinyl acetate/acrylates and ethylene/vinyl acetate copolymers, water-soluble binders, for example polyvinyl alcohols and/or crosslinkers, for example polyurethanes or polyurethane dispersions, polyacrylates, polyolefin dispersions, epoxysilanes, for example 3-glycidoxypropyltrialkoxysilane.

The dispersion is applied to a suitable substrate or first layer by known methods, for example by spin coating, dipping, injection, drop-by-drop addition, spraying, sputtering, knife coating, brushing or printing methods, for example inkjet printing, gravure printing, screen printing, flexographic printing or embossing.

The first and second layers comprising at least one polymeric anion and at least one polythiophene having a repeating unit of the general formula (I) or (II-a) and/or (II-b) can be applied by cleaning the layer (e.g. by washing) after curing (e.g. by drying).

The preparation of dispersions from thiophenes of the general formula (II) can be carried out, for example, under conditions analogous to those described in EP-A440957. To obtain these particle sizes, the dispersion is preferably subjected to one or more homogenization treatments, optionally under high pressure, to produce the first layer in a manner known to those skilled in the art. The solids content can be pre-adjusted to the desired extent by selecting the amount of solvent, which can then optionally be present in a known manner or be reduced by dilution or be increased by concentration.

It is also possible to prepare polythiophene/polyanion complexes and then disperse or redisperse them in one or more solvents.

In the case of a dispersion containing a solvent, the first layer is cured before the second layer is applied, in particular by removing the solvent or by means of oxidative crosslinking, preferably by exposing the dispersion layer to (ambient) oxygen.

The optional solvent can be removed after the solution has been applied by simple evaporation at room temperature. However, for faster processing speeds, it is advantageous to remove the solvent at higher temperatures, for example at temperatures of from 20 to 300 ℃ and preferably from 40 to 200 ℃. Depending on the additives in the dispersion used for producing the first electrode layer, the drying temperature is particularly preferably selected in the range from 100 to 150 ℃. The heat-treatment can be carried out immediately after the solvent is removed or after the coating has been formed for a certain time. The heat treatment may last from 5 seconds to several hours, depending on the nature of the polymer used for the coating. Temperature profiles with different temperatures and durations may also be used for the heat treatment.

The thermal treatment may be performed, for example, by moving the coated substrate through a heating chamber at a predetermined temperature and at a speed such that a predetermined duration is reached at the selected temperature, or by contacting it with a hot plate at a predetermined temperature and for a predetermined duration. The heat treatment can also be carried out in one heating furnace or in several heating furnaces, for example each having a different temperature.

The substrate may be, for example, glass, very thin glass (flexible glass) or plastic. The substrate may be treated with an adhesion promoter prior to applying the layer comprising at least one conductive polymer. Such treatment is carried out, for example, by spin coating, dipping, injection, drop-by-drop addition, spraying, sputtering, knife coating, brushing or printing, for example ink-jet printing, gravure printing, screen printing, flexographic printing or embossing.

Plastics particularly suitable for the substrate are: polycarbonates, such as PET and PEN (polyethylene terephthalate and polyethylene naphthalate, respectively), copolycarbonates, polysulfone, Polyethersulfone (PES), polyimide, polyethylene, polypropylene or cyclic polyolefins or Cyclic Olefin Copolymers (COC), hydrogenated styrene polymers or hydrogenated styrene copolymers.

Suitable polymer substrates may be thin films, for example polyester films from Sumitomo, PAES films or from Bayer AG (Makrofol)^®) The polycarbonate film of (1).

Preferred low molecular weight hole injection materials are optionally substituted phthalocyanines, such as copper phthalocyanine (S.A. Van Slyke et al, appl.Phys.Lett.69(1996)2160), or optionally substituted anilines, such as 4, 4 '-bis (3-methylphenylphenylamino) biphenyl (TPD) or 4, 4' -tris (3-methylphenylphenylamino) triphenylamine (m-MTDATA) (Y.Shirota et al, appl.Phys.Lett.65(1994)807), which may also optionally be doped with 2, 3, 5, 6-tetrafluoro-7, 7, 8, 8-tetracyanoquinodimethane (F4-TCNQ) or other donors or acceptors (M.Pferffer et al, adv.Mat.14(2002) 1633).

The second layer of the electrode according to the invention may be applied from a solution, dispersion or gas phase, depending on the hole injection material. The second layer is preferably made from a solution or dispersion. In a preferred embodiment of the process according to the invention, the second layer is made from a dispersion comprising at least one polymer anion and at least one optionally substituted polythiophene comprising recurring units of the general formula (II-a) and/or (II-b).

The method according to the invention is therefore preferably carried out without the need for complex and expensive physical vapour deposition or sputtering processes. It may also allow application over larger surfaces. Furthermore, the polythiophene/polyanion layer can be applied at low temperatures, preferably at room temperature. The method according to the invention is thus also suitable for application on polymeric flexible substrates which are normally only able to withstand low temperature processing and not the ITO deposition temperature.

The invention also provides an electrode which can be produced, preferably has been produced, by the method according to the invention.

The electrode according to the invention is preferably a transparent electrode. Transparent within the meaning of the present invention means transparent to visible light.

The standard color value Y of the first layer of the electrode according to the invention is preferably at least Y (D65/10 °) -50, particularly preferably at least Y (D65/10 °) -70.

The light transmittance was measured according to wavelength according to ASTM D1003 and used to calculate a standard color value Y (also commonly referred to as brightness) according to ASTM E308. For a completely transparent sample, Y is 100, and for an opaque sample, Y is 0. In the terminology of optical engineering, Y (D65/10 °) is to be understood as the standard color value (ASTM E308) observed at an angle of 10 ° with the standard light type D65. The standard color values refer to the pure color layers, i.e. the uncoated substrate is also measured as a control.

The first layer of the electrode according to the invention is preferably at least 300Scm conductive^-1Particularly preferably at least 400 Scm^-1。

Conductivity is understood to be the inverse of the specific resistance. This is calculated from the product of the sheet resistance and the film thickness of the conductive polymer layer. The surface resistance of the conductive polymer is determined in accordance with DIN ENISO 3915, and the thickness of the polymer layer is determined using a sharp-pointed topography detector.

Furthermore, the first layer of the electrode according to the invention preferably has a surface roughness Ra of less than 2.5nm, preferably less than 1.5 nm.

The surface roughness Ra was measured by 1 μm area scanning of a polymer layer approximately 150nm thick on a glass substrate using a scanning force microscope (Digital Instruments).

The surface roughness of the first layer of the electrode according to the invention is significantly smaller than in the known electrode of EP-a686662, for example, so that the possibility of short circuits with the electrodes OLED and OSC according to the invention is reduced.

The first layer of the electrode according to the invention also preferably has a dry film thickness of from 10 to 500nm, particularly preferably from 20 to 200nm, most preferably from 50 to 200 nm. The second layer of the electrode according to the invention preferably has a dry film thickness of from 5 to 300nm, particularly preferably from 10 to 200nm, most preferably from 50 to 150 nm.

In a preferred embodiment, the electrode contains a first layer consisting of a polyanion and a polythiophene having a repeating unit of the general formula (I), wherein R, A and x have the meaning indicated above, to which a second layer consisting of a polythiophene comprising a polymer anion and a repeating unit of the general formula (II-a) and/or (II-b) is applied.

In a most preferred embodiment, the electrode comprises a first layer of polystyrene sulfonic acid and poly (3, 4-ethylenedioxythiophene) to which a second layer of polystyrene sulfonic acid and poly (3, 4-ethylenedioxythiophene), also known in the industry as PEDT/PSA or PEDT: PSA, is applied.

The electrodes according to the invention are very suitable for use as electrodes in electrical, preferably optoelectronic, structures, in particular in Organic Light Emitting Diodes (OLEDs), Organic Solar Cells (OSCs), electrophoretic or Liquid Crystal Displays (LCDs) and optical sensors.

The opto-electronic structure typically comprises two electrodes, at least one of which is transparent, and an opto-electronically active coating system between the two electrodes. In the case of OLEDs, the optoelectronic structure is an electroluminescent layer device, hereinafter also simply referred to as electroluminescent device or EL device.

The simplest case of such an EL device comprises two electrodes, at least one of which is transparent, and an electro-optically active layer between the two electrodes. However, other functional layers, such as other charge injection, charge transport, or charge blocking interlayers, may also be included in the electroluminescent layer structure. Such layer structures are known to those skilled in the art and are described, for example, (J.R. shoes et al, Science 273(1996), 884). One layer may also have multiple functions. In the simplest EL device, the electro-optically active layer, i.e., usually the light-emitting layer, may function as another layer. One or both electrodes may be applied to a suitable substrate, i.e. a suitable carrier. The layer structure is then provided with suitable contacts and optionally enclosed and/or wrapped.

The structure of the multilayer system can be obtained by Physical Vapor Deposition (PVD), wherein the layers are applied continuously from the gas phase, or by casting. The use of physical vapor deposition in combination with shadow masking produces structured LEDs that use organic molecules as the light emitter. The method of casting moulds is generally preferred due to the higher processing speeds and the lower amount of scrap generated, which results in cost savings.

As mentioned above, the electrode according to the invention can advantageously be manufactured by means of a solution/dispersion.

The invention therefore also provides an electroluminescent arrangement consisting of at least two electrodes, at least one of which is transparent, and an electro-optically active layer between the two electrodes, characterized in that it contains an electrode according to the invention as the transparent electrode.

A preferred electroluminescent arrangement comprises electrodes according to the invention applied to a suitable substrate, i.e. the first and second layers, a light-emitting layer and a metal cathode. In such an EL device, the layer containing at least one organic hole-injecting material, preferably at least one polymer anion and at least one polythiophene having the general formula (II-a) or (II-b) can, for example, function as a hole-injecting interlayer. Optionally including other functional materials listed above.

In particular, the conductive layer is arranged in contact with several highly conductive metal wires as anodes.

A preferred embodiment of the invention is an EL device consisting of the following layer sequence:

substrate// (polyethylenedioxythiophene/polystyrenesulfonic acid) layer (first layer)// (polyethylenedioxythiophene/polystyrenesulfonic acid) layer (second layer)// light-emitting layer// metal cathode.

Optionally including other functional layers.

The corresponding structure with the electrode according to the invention is also very advantageous in an inverted OLED or OSC structure, i.e. in case the layers are assembled in the reverse order. A preferred embodiment of a corresponding inverted OLED is as follows:

substrate// metal cathode// light emitting layer// (polyethylenedioxythiophene/polystyrenesulfonic acid) layer (second layer)/(polyethylenedioxythiophene/polystyrenesulfonic acid) layer (first layer).

Inverted OLEDs, particularly in combination with active matrix substrates, have received much attention. The active matrix substrate is typically a non-transparent Si layer with transistor circuitry beneath each light-emitting pixel.

If the electrode according to the invention is used in an inverted OLED, the second layer is generally applied first to the light-emitting layer, as described above, and then the first layer is applied to the light-emitting layer as soon as the second layer has cured, as described above.

Suitable light-emitting materials and materials for the metal cathode are those which are commonly used in photovoltaic structures and are known to those skilled in the art. The metal cathode is preferably made of a low work function metal, such as Mg, Ca, Ba, Cs or metal salts such as LiF. Preference is given to using conjugated polymers such as polyphenylenevinylenes or polyfluorenes or emitters from low molecular weight emitter classes, also known in the industry as "small molecule substances", for example tris (8-hydroxyquinoline) aluminum (Alq)₃) As a light emitting material.

In the photovoltaic structure, the electrode according to the invention has a number of advantages over known electrodes:

a) for example in OLEDs and OSCs, there is no need for TCO layers, such as ITO, or thin metal layers.

b) In the case of flexible substrates, the bending of the substrate does not lead to cracking of the fragile TCO layer and failure of the opto-electronic structure, since these polymer layers are very flexible and tough.

c) The structure of the organic layer is simpler than that of the inorganic layer, such as ITO. The organic layer can be removed again with a solvent, by light radiation (UV) or by thermal radiation (laser ablation).

The bilayer electrode according to the present invention comprises a first and a second layer, which also has significant advantages over known polymer electrodes. The probability of short circuits of OLEDs and OSCs with electrodes according to the invention is greatly reduced, in particular due to the fine particle structure and the low surface roughness. The significantly improved conductivity of the first layer is also surprising as it is described in the literature that decreasing the particle size increases the sheet resistance of the resulting layer (a. elschner et al, Asia Displa IDW 2001, OEL3-3, p.1429). Even the addition of conductivity-enhancing additives should not offset this negative effect of particle fineness on conductivity, and in particular further enhance conductivity. The electroluminescent efficiency of an OLED can be significantly improved by using the electrode according to the present invention. Especially with an electrode according to a particularly preferred embodiment of the invention, wherein both the first and the second electrode layer comprise PEDT: PSA, the electroluminescent efficiency can be increased by 1 to 3 orders of magnitude compared to a single layer electrode at the same device current.

The effect obtained is unexpected since the only electroactive component of the two layers is the conductive polythiophene, whereas the polymeric anions are electrically inert and serve primarily to keep the conductive polymer or polythiophene in solution during the polymerization and to substantially volatilize away the conductivity-enhancing additive at drying temperatures above 120 ℃.

In order to keep the voltage drop between the anode contact and the OLED anode very low, highly conductive wires, i.e. busbars, made of metal can be used.

In the case of a passive matrix OLED display, the present invention may omit ITO address lines. In its place, the metal conductors (busbars) associated with the electrodes of the invention are addressed on the anode side (see fig. 1). A conductive line 2a having high conductivity and a pixel frame 2b are applied to a transparent support 1, such as a glass plate. They can be applied by metal vapor deposition or by inexpensive metal solder printing. A polymer electrode layer 3 is then deposited onto the frame. The adhesion promoter is optionally applied first, followed by the first electrode layer and finally the second electrode layer. These layers are preferably applied by spin coating, printing and ink jet printing. The remaining structure corresponds to that in a standard passive matrix OLED and is known to the person skilled in the art.

In OLEDs which emit light homogeneously (OLED lamps), the invention makes it possible to dispense with ITO electrodes. In its place, the metal conductor (busbar) associated with the electrode of the invention functions as a full-surface anode (see fig. 2). The electrically conductive wires 2 with high electrical conductivity are applied to a transparent carrier 1, such as a glass plate, for example in the manner described in the preceding paragraph. The polymer electrode layer 3 is then deposited thereon in the order described in the previous paragraph. The remaining structure corresponds to that in a standard OLED lamp.

The present invention provides a dispersion liquid particularly suitable for producing the first electrode layer, which is also not described in the literature.

Detailed Description

The following examples are intended to illustrate the invention by way of example and should not be construed as limiting.

Examples

The particle size distributions given below are determined using analytical ultracentrifuges, e.g. h.g. muller; progr, colloid Polymer, Sci.127(2004) 9-13.

The light transmittance was measured according to wavelength in accordance with ASTM D1003, and used to calculate a standard color value Y in accordance with ASTM E308. For a completely transparent sample, Y is 100, and for an opaque sample, Y is 0. In the terminology of optical engineering, Y (D65/10 °) is to be understood as the standard color value (cf. astm e308) observed at an angle of 10 ° with the standard light type D65. The light transmittance was measured using a UV/VIS spectrophotometer (PerkinElmer 900 with an integrating sphere) with an uncoated glass substrate placed in the control beam path.

The solution viscosity was measured using a Haake RV 1 rheometer with a thermostat. 13.5 g. + -. 0.3g of the solution to be measured are weighed into a clean and dry measuring cup, placed in a measuring slit and kept at 20.0 ℃ for 100s^-1Is measured at a shear rate of (c).

Conductivity is understood to be the inverse of the specific resistance. This is calculated from the product of the sheet resistance and the film thickness of the conductive polymer layer. The surface resistance of the conductive polymer is determined in accordance with DIN ENISO 3915, and the thickness of the polymer layer is determined using a sharp-pointed topography detector.

The surface roughness Ra was measured by 1 μm area scanning of a polymer layer approximately 150nm thick on a glass substrate using a scanning force microscope (Digital Instruments).

Example 1

Preparation of PEDT PSA Dispersion for the manufacture of the first electrode layer

a) (according to the invention) in a commercially available polyethylenedioxythiophene/polystyrenesulfonic acid dispersion (PEDT: PSA dispersion) with a polyethylenedioxythiophene/polystyrenesulfonic acid weight ratio of 1: 2.5 and a solids content of about 1 wt.% at 100s^-1A shear rate of about 300mPas (Baytron of H.C. Starck GmbH) and a viscosity at 20 ℃^®PHCV4) with a d50 value of 25nm, i.e. 50 wt.% of the particles are smaller than 25nm, established by a homogenization treatment. The dispersion was then concentrated from about 1 wt.% to a solid content of 1.7 wt.%, filtered (Pall, pore size: 0.2 μm) and then mixed with 5 wt.% dimethyl sulfoxide (DMSO). At 20.0 deg.C for 100s^-1The viscosity of the solution at shear rate of (a) is about 45 mPas.

b) Comparative example A commercially available poly (ethylenedioxythiophene)/polystyrene sulfonic acid dispersion (PEDT: PSA dispersion) was filtered, wherein the poly (ethylenedioxythiophene)/polystyrene acid weight ratio was 1: 2.5, the solids content was about 1 wt.%, and the concentration was 100s^-1A shear rate of about 300mPas (Baytron of H.C. Starck GmbH) and a viscosity at 20 ℃^®PHC V4) with a d50 value of 25nm for the particle size distribution. Due to its roughness, this dispersion can only be filtered through a 10 μm filter.

c) Comparative example a PEDT: PSA dispersion was prepared as described in 1b) and then mixed with 5 wt.% dimethyl sulfoxide. Due to its coarseness, this dispersion can only be filtered through a 10 μm filter.

Example 2

Preparation and characterization of the first electrode layer

a) (according to the invention) the glass substrate was cut to 50X 50mm²Clean and activate with UV/ozone for 15 minutes. The dispersion of example 1a) was then coated on the glass substrate by means of a spin coater at a specific spin speed and an acceleration of 500rpm/sec for 30 seconds. Parallel silver contacts were vapor deposited using a shadow mask and the surface resistance was measured. The film thickness was measured with a stylus-type topography instrument (Tencor 500) and the surface roughness was measured with a scanning force microscope (Digital Instruments).

b) Comparative example a glass substrate was prepared as described in 2a), coated with the dispersion of example 1b), and its standard color value, surface resistance, film thickness and surface roughness were determined.

c) Comparative example a glass substrate was prepared as described in 2a), coated with the dispersion of example 1c), and its standard color value, surface resistance, film thickness and surface roughness were determined.

Table 1: film thickness, conductivity, standard color value and surface roughness of the first electrode layer of examples 2a), b) and c)

Examples	Rotational speed [ rpm]	Film thickness [ mm ]]	Conductivity [ S/cm ]]	Standard color value Y (D65/10 degree)	Surface roughness Ra nm]
						2a)	950	129	621	89.1	1.39
2b)	1250	146	56	86.9	1.93
						2c)	1200	158	601	85.3	3.53

Comparison of the electrode layers of examples 2a) to 2c) shows that, in addition to having comparable film thickness and standard color values, the first electrode layer of example 2a) has the highest conductivity, while the surface roughness is the lowest.

Example 3

Preparation of an OLED without a second electrode layer

1. Substrate with gold finger (metallic finger)

Cutting the glass substrate into 50X 50mm²And cleaned. The gold fingers in the silver are then vapor deposited onto the substrate using a shadow mask. Parallel metal lines 1mm wide and 5mm spaced are connected by a central strip (central bar) perpendicular thereto and 170nm in height. The coating was performed immediately after cleaning and activating the substrate with UV/ozone (UVP inc., PR-100) for 15 minutes.

2. Application of a first electrode layer Using the PEDT PSA Dispersion according to the invention

Approximately 2ml of the dispersion according to example 1a) are poured onto a substrate with a gold finger and coated by means of a spin coater at a speed of 1000rpm and an acceleration of 500rpm/sec on a glass substrate for 30 seconds. The substrate with the still wet electrode layer was then placed on a hot plate, covered with a Petri dish and dried at 200 ℃ for 5 minutes. The electrode layer was approximately 170nm thick and the conductivity was 356S/cm.

3. Applying a luminescent layer

About 2ml of a 1 wt.% luminophore Greenn 1300LUMATION^TMIs filtered (millipore hv, 0.45 μm) and coated onto a dried first electrode layer (hereinafter also referred to as DGP) (Dow Chemical Company). At 500rpmThe plate was rotated at a speed and an acceleration of 200rpm/sec for 30 seconds to decant the supernatant of the luminophores. The substrate thus coated was then dried on a hot plate at 110 ℃ for 5 minutes. The total coating thickness was 250 nm.

4. Applying metal cathodes

A metal electrode is vapor deposited onto the light-emitting layer. The vapor deposition system (Edwards) used for this step was constructed as an inert gas glove box (Braun). The substrate is placed on a shadow mask having an underlying light emitting layer. The aperture in the shadow mask was 2.0mm with a 5.0mm spacing. The shadow mask is positioned so that the holes are located exactly between the gold fingers. When p is 10^-3A5 nm thick Ba layer and a 200nm Ag layer were vapor-deposited successively from two vapor deposition boats under Pa. The vapor deposition rate was Ba: 10 Å/sec, Ag: 20 Å/sec.

5. Characterization of the OLED

For the electro-optical properties, the two electrodes of the OLED are connected to a power supply via electrically conductive lines. The positive electrode was connected to a gold finger and the negative electrode was connected to one of the vapor deposited circular metal electrodes.

The dependence of the OLED current and the electroluminescence intensity (EL) on the voltage (Keithley2400 current/voltage source) was recorded. EL was measured with a photodiode (EG & GC30809E) of an electrometer (Keithley 6514) and the brightness was measured with a brightness meter (Minolta LS-100).

Example 4

Preparation of an OLED having a first and a second electrode layer according to the invention

The operation was as in example 3, except that between steps 2 and 3 the ratio of PEDT: a second electrode layer of PSA. For this purpose, 2ml of an aqueous PEDT: PSA dispersion (Baytron from H.C. Starck GmbH) which had been filtered (Millipore HV, 0.45 μm) were dispersed in water^®P CH8000, PEDT: PSA weight ratio of 1: 20, solid content of about 2.5 wt.%, at 700s^-1And a viscosity of about 12mPas at 20 ℃) by means of a spinner at 1A speed of 000rpm and an acceleration of 200rpm/sec were applied to the glass substrate for 30 seconds. The substrate with the still wet second electrode layer was then placed on a hot plate, covered with a Petri dish and dried at 200 ℃ for 5 minutes. The total film thickness of the two electrode layers was 270 nm.

Table 2: current I, luminance L and efficiency η of the OLEDs of examples 3 and 4

	4V			8V
								I[mA/cm2]	L[cd/m2]	η[cd/A]	I[mA/cm2]	L[cd/m2]	η[cd/A]
Example 4	7.0	19	0.27	385.4	7230	1.88
							Example 3	18.9	660	3.48	503.2	20148	4.00

This comparison shows that the OLED according to the invention with two electrodes of example 4 surprisingly has a significantly higher luminance L and efficiency η than the OLED of example 3 with only one electrode in the relevant voltage range.

Comparative example 5

The operation was as in example 3, with the following differences in film thickness:

the device structure:

gold finger// first electrical base layer (75nm)// DGP (80nm)// Ba// Ag

Example 6 (according to the invention)

The operation was as in example 4, with the following differences in film thickness:

the device structure:

gold finger// first electrode layer (75nm)// second electrode layer (80nm)// DGP (80nm)// Ba// Ag

Comparative example 7

The procedure was as in example 5, except that: the first electrode layer was produced using the dispersion of example 1b) instead of the dispersion of example 1 a).

The device structure:

gold finger// first electrical base layer (80nm)// DGP (80nm)// Ba// Ag

Comparative example 8

The procedure was as in example 6, except that: the first electrode layer was produced using the dispersion of example 1b) instead of the dispersion of example 1 a).

The device structure:

gold finger// first electrode layer (80nm)// second electrode layer (80nm)// DGP (80nm)// Ba// Ag

The characterization of the OLEDs was carried out as described in examples 3 and 4.

Table 3: current I, luminance L and efficiency η of the OLEDs of examples 5 to 8

	4V				8V
										I[mA/cm2]	L[cd/m2]	η[cd/A]	I+/I-	I[mA/cm2]	L[cd/m2]	η[cd/A]	I+/I-
Example 5	28.6	128	0.45	1.40E+01	524.5	9052	1.73	1.84E+01
									Example 6	21.4	1300	6.07	3.50E+05	477.6	25730	5.39	7.09E+04
Example 7	17.1	138	0.80	4.20E+00	500.0	18600	3.72	7.42E+00
									Example 8	25.7	1628	6.33	4.20E+01	383.7	21700	5.66	1.88E+01

The comparison again shows that the OLED according to the invention of example 6 with two electrodes surprisingly has a significantly higher luminance L and efficiency η than the OLEDs of comparative examples 5 and 7 with only one electrode in the relevant voltage range. Furthermore, this comparison shows that the OLED according to the invention of example 6 with two-layer electrodes made from the dispersion according to the invention has a much higher rectification ratio (I +/I-) than the OLED of comparative example 8 with two-layer electrodes.

Claims (19)

1. A method for manufacturing an electrode comprising at least two layers, characterized in that:

the first layer is prepared by applying a dispersion comprising at least one polymer anion and at least one optionally substituted polythiophene comprising recurring units of the general formula (I) on a suitable substrate,

wherein

A represents optionally substituted C₁To C₅An alkylene group or a substituted alkylene group,

r represents a linear or branched, optionally substituted C₁To C₁₈Alkyl, optionally substituted C₅To C₁₂Cycloalkyl, optionally substituted C₆To C₁₄Aryl, optionally substituted C₇To C₁₈Aralkyl, optionally substituted C₁To C₄A hydroxyalkyl group or a hydroxyl group,

x represents an integer of 0 to 8, and

if several radicals R are attached to A, they may be identical or different,

50 wt.% of the particles in the dispersion are smaller than 50nm, then allowed to solidify, and then

The second layer is prepared by applying at least one organic hole-injecting material and optionally at least one anion (obtained from a solution or dispersion by physical vapour deposition) onto the first layer and then optionally curing it.

2. A process according to claim 1, characterized in that the dispersion used for making said first layer contains at least 0.1 wt.%, based on the total weight of the dispersion, of one or more additives selected from ether group-containing compounds, lactone group-containing compounds, amide or lactam group-containing compounds, sulfones, sulfoxides, sugars or sugar derivatives, sugar alcohols, furan derivatives and diols or polyols.

3. The method according to claim 1 or 2, characterized in that in the general formula (I), a represents, independently of each other, an optionally substituted C for the recurring units of the polythiophene in the first layer₂To C₃Alkyl, x represents 0 or 1.

4. Process according to at least one of claims 1 to 3, characterized in that the polythiophene comprising recurring units of the general formula (I) is poly (3, 4-ethylenedioxythiophene).

5. Method according to at least one of claims 1 to 4, characterized in that the polymeric anion is a polymeric carboxylic or sulfonic acid anion, preferably a polystyrene sulfonic acid anion.

6. The process according to at least one of claims 1 to 5, characterized in that the optionally substituted polythiophene comprising a repeating unit of the general formula (I) and the polymer anion are present in a weight ratio of 0.5: 1 to 20: 1 in the first layer.

7. Method according to at least one of the claims 1 to 6, characterized in that the organic hole injection material is a polymer or a low molecular weight material.

8. The method according to at least one of claims 1 to 7, characterized in that the organic hole injection material is an optionally substituted polythiophene comprising recurring units of the general formula (II-a) and/or (II-b),

wherein

A represents optionally substituted C₁To C₅An alkylene group or a substituted alkylene group,

y represents O or S, and Y represents O or S,

r represents a linear or branched, optionally substituted C₁To C₁₈Alkyl, optionally substituted C₅To C₁₂Cycloalkyl, optionally substituted C₆To C₁₄Aryl, optionally substituted C₇To C₁₈Aralkyl, optionally substituted C₁To C₄A hydroxyalkyl group or a hydroxyl group,

x represents an integer of 0 to 8, and

if several radicals R are attached to A, they may be identical or different and optionally also contain at least one polymer anion.

9. Process according to claim 8, characterized in that the second layer is prepared by applying onto the first layer a dispersion containing at least one optionally substituted polythiophene having repeating units of the general formula (II-a) and/or (II-b), said dispersion optionally also comprising at least one polymer anion, and then curing it.

10. Process according to claim 8 or 9, characterized in that the polythiophene having a repeating unit of the general formula (II-a) and/or (II-b) is poly (3, 4-ethylenedioxythiophene).

11. Method according to at least one of claims 1 to 10, characterized in that the organic hole injection material is an optionally doped material selected from optionally substituted phthalocyanines or anilines.

12. Electrode obtained by the method of at least one of claims 1 to 11.

13. An electrode according to claim 12, characterized in that the first layer has a conductivity in the dry state of at least 300Scm^-1。

14. The electrode according to claim 12 or 13, characterized in that the surface roughness Ra of the first layer is less than 2.5 nm.

15. Electrode according to at least one of claims 12 to 14, characterized in that the dry film thickness of the first layer is 10 to 500 nm.

16. Use of an electrode according to at least one of claims 12 to 15 as a transparent electrode in an optoelectronic structure.

17. Use according to claim 16 as transparent electrode in organic light emitting diodes, organic solar cells, electrophoretic or liquid crystal displays and optical sensors.

18. Electroluminescent arrangement comprising at least two electrodes, at least one of which is transparent, and an opto-electronically active layer between the two electrodes, characterized in that an electrode according to at least one of claims 12 to 15 is contained as the transparent electrode.

19. Comprising at least one polymer anion, at least one solvent and at least one optionally substituted polythiophene comprising a repeating unit of the general formula (I),

characterized in that 50% by weight of the particles are smaller than 50nm and that they contain at least 0.1% by weight, based on the total weight of the dispersion, of one or more additives selected from the group consisting of ether group-containing compounds, lactone group-containing compounds, amide or lactam group-containing compounds, sulfones, sulfoxides, sugars or sugar derivatives, sugar alcohols, furan derivatives and diols or polyols.