Polythiophene compositions for improving organic light-emitting diodes

The invention relates to formulations containing polythiophenes and other polymers, their use and electroluminescent arrangements containing hole-injecting layers containing these formulations.

An electroluminescent arrangement (EL arrangement) is characterized in that it emits light when an electrical voltage is applied under current flow. Such arrangements have long been known under the name "light emitting diodes" (LEDs). The emission of light comes about because positive charges (holes, "holes") and negative charges (electrons, "electrons") recombine while emitting light.

The LEDs commonly used in technology are all predominantly made of inorganic semiconductor materials. However, EL arrangements have been known for some years, the essential components of which are organic materials.

These organic EL arrangements usually contain one or more layers of organic charge transport compounds.

The basic layer structure of an EL arrangement is, for example, as follows:<dl id="dl0001" compact="compact"><dt>1</dt><dd>Carrier, substrate</dd><dt>2</dt><dd>Base electrode</dd><dt>3</dt><dd>Hole-injecting layer</dd><dt>4</dt><dd>Hole-transporting layer</dd><dt>5</dt><dd>Emitter layer</dd><dt>6</dt><dd>Electron transport layer</dd><dt>7</dt><dd>Electron injecting layer</dd><dt>8</dt><dd>Top electrode</dd><dt>9</dt><dd>contacts</dd><dt>10</dt><dd>Wrapping, encapsulation</dd></dl>

This structure is the most detailed case and can be simplified by omitting individual layers so that one layer takes on multiple tasks. In the simplest case, an EL arrangement consists of two electrodes, between which there is an organic layer that fulfills all functions - including the emission of light.

However, it has been shown in practice that electron and / or hole-injecting layers in the electroluminescent structures are particularly advantageous for increasing the luminance.

From the <patcit id="pcit0001" dnum="EP686662A"><text>EP-A-686 662</text></patcit> is known to use special mixtures of conductive organic polymeric conductors such as poly (3,4-ethylenedioxythiophene) and for example polyhydroxy compounds or lactams as electrodes in electroluminescent displays. However, it has been shown in practice that these electrodes do not have sufficient conductivity, especially for large-area displays. For small displays (illuminated area &lt;1cm²) the conductivity is sufficient.

From the <patcit id="pcit0002" dnum="DE19627071A"><text>DE-A-196 27 071</text></patcit> is known to use polymeric organic conductors, such as poly (3,4-ethylenedioxythiophene), as hole-injecting layers. As a result, the luminosity of the electroluminescent displays can be significantly increased compared to structures without the use of polymeric organic intermediate layers. The conductivity can be specifically adjusted by reducing the particle size of the poly (3,4-alkylenedioxythiophene) dispersions. This makes it possible to prevent electrical crosstalk from neighboring address lines (crosstalk), especially in passive matrix displays (<patcit id="pcit0003" dnum="EP1227529A"><text>EP-A-1 227 529</text></patcit>).

However, the lifespan of these displays is still not sufficient for many practical applications.

There was therefore still a need to produce EL arrangements which, in addition to a high luminosity (luminous intensity), have a longer service life than known EL arrangements.

The object of the present invention was therefore to find and provide suitable formulations for the production of such EL arrangements. Another object was to produce improved EL devices from these materials.

It has surprisingly been found that previously unknown formulations containing optionally substituted polythiophenes or optionally substituted polyanilines or polypyrroles and other polymers are outstandingly suitable for producing hole-injecting layers for EL arrangements and that the EL arrangements obtained have a significantly longer service life than known EL arrangements.

The present invention therefore relates to formulations comprising<ol id="ol0001" ol-style=""><li>A) at least one polythiophene containing recurring units of the general formula (I),<chemistry id="chem0001" num="0001"><img file="EP1564251B1_D0001.tif" /></chemistry>    wherein<dl id="dl0002"><dt>A</dt><dd>for an optionally substituted C₁-C₅Alkylene radical, preferably an optionally substituted ethylene or propylene radical, particularly preferably a 1,2-ethanediyl radical,</dd><dt>R</dt><dd>for a linear or branched C₁-C₁₈Alkyl radical, preferably for a linear or branched C₁-C₁₄Alkyl radical, particularly preferably for a methyl or ethyl radical, a C₅-C₁₂Cycloalkyl radical, a C₆-C₁₄Aryl residue, a C₇-C₁₈Aralkyl radical, a C₁-C₄-Hydroxyalkyl radical or a hydroxyl radical,</dd><dt>x</dt><dd>represents an integer from 0 to 8, preferably 0, 1 or 2, particularly preferably 0 or 1 and</dd></dl>in the event that several R radicals are bonded to A, these may be the same or different,</li><li>B) at least one SO₃^-M⁺- or COO^-M⁺-Group-containing polymer, where M⁺ for H⁺, Li⁺, N / A⁺, K⁺, Rb⁺, Cs⁺ or NH₄⁺, preferred for H⁺, N / A⁺ or K⁺ stands, and</li><li>C) at least one SO₃^-M⁺- or COO^-M⁺-Groups containing, partially fluorinated or perfluorinated polymer, where M⁺ for H⁺, Li⁺, N / A⁺, K⁺, Rb⁺, Cs⁺ or NH₄⁺, preferred for H⁺, N / A⁺ or K⁺ stands.</li></ol>

The general formula (I) is to be understood such that the substituent R can be bonded to the alkylene radical A x times.

Formulation (composition) in the sense of the invention is any mixture of components A), B) and C) as a solid, solution or dispersion. Instead of polythiophene A), other known conductive polymers A) can also be used, in particular optionally substituted polyanilines or polypyrroles. These various conductive polymers can be used alone or in any mixture.

Substituted here and in the following, unless expressly stated otherwise, is a substitution with a group selected from the series:

Alkyl, preferably C₁-C₂₀-Alkyl-, cycloalkyl-, preferably C₃-C₂₀-Cycloalkyl-, aryl-, preferably C₅-C₁₄Aryl, halogen, preferably Cl, Br, J, ether, thioether, disulfide, sulfoxide, sulfone, amino, aldehyde, keto, carboxylic acid ester, cyano, alkylsilane and alkoxysilane groups and carboxylamide groups to understand.

In preferred embodiments of the formulation according to the invention, at least one polythiophene containing recurring units of the general formula (I) is one containing recurring units of the general formula (Ia),<chemistry id="chem0002" num="0002"><img file="EP1564251B1_D0002.tif" /></chemistry>wherein R and x have the meaning given above.

In very particularly preferred formulations as described above, x stands for 0 or 1. In the event that x is 1, R particularly preferably stands for methyl or hydroxymethyl.

In further preferred embodiments of the formulation according to the invention, at least one polythiophene A) containing recurring units of the general formula (I) is such a recurring unit of the general formula (Iaa)<chemistry id="chem0003" num="0003"><img file="EP1564251B1_D0003.tif" /></chemistry>

The prefix poly in the context of the invention means that more than one identical or different repeating unit is contained in the polymer or polythiophene. The polythiophenes contain a total of n recurring units of the general formula (I), where n can be an integer from 2 to 2000, preferably 2 to 100. The repeating units of the general formula (I) can in each case be the same or different within a polythiophene. Preference is given to polythiophenes each containing the same repeating units of the general formula (I).

In the context of the invention, repeating units are to be understood as meaning units of the general formulas (I), (Ia) or (Iaa), summarized below as repeating units of the general formula (I), regardless of whether they are used one or more times in polythiophene are included. Ie units of the general formula (I) are also to be understood as recurring units if they are contained only once in the polythiophene.

Formulations according to the invention can also be those which, in addition to at least one of the polythiophenes A) described above and containing recurring units of the general formula (I), contain further conductive polymers, such as polyanilines or polypyrroles, in the mixture.

The polythiophenes preferably each carry H.

The polythiophenes A) contain a total of n recurring units of the general formula (I), where n is preferably an integer from 2 to 1000, preferably 3 to 100, particularly preferably 4 to 15.

C.₁-C₅Alkylene radicals A are in particular methylene, ethylene, n-propylene, n-butylene or n-pentylene. C.₁-C₁₈-Alkyl stands especially for linear or branched C₁-C₁₈Alkyl radicals, for example methyl, ethyl, n- or isopropyl, n-, iso-, sec- or tert-butyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 1-ethylpropyl, 1, 1-dimethylpropyl, 1,2-dimethylpropyl, 2,2-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, C₅-C₁₂-Cycloalkyl for C₅-C₁₂-Cycloalkyl radicals such as cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl or cyclodecyl, C₅-C₁₄Aryl for C₅-C₁₄Aryl radicals, for example phenyl or naphthyl, and C₇-C₁₈Aralkyl for C₇-C₁₈Aralkyl radicals, for example benzyl, o-, m-, p-tolyl, 2,3-, 2,4-, 2,5-, 2,6-, 3,4-, 3,5-xylyl or mesityl. The above list serves to explain the invention by way of example and is not to be regarded as conclusive.

The preparation of the polythiophenes A) described above containing recurring units of the general formula (I) is in principle in <patcit id="pcit0004" dnum="EP440957A"><text>EP-A 440 957</text></patcit> described.

The polymerization of the corresponding monomeric starting compounds is carried out using suitable oxidizing agents in suitable solvents. Examples of suitable oxidizing agents are iron (III) salts, in particular FeCl₃ and iron (III) salts of aromatic and aliphatic sulfonic acids, H₂O₂, K₂Cr₂O₇, K₂S₂O₈, N / A₂S₂O₈, KMnO₄, Alkali perborates and alkali or ammonium persulfates or mixtures of these oxidizing agents. Other suitable oxidizing agents are, for example, in<nplcit id="ncit0001" npl-type="b"><text>Handbook of Conducting Polymers (Ed. Skotheim, TA), Marcel Dekker: New York, 1986, Vol. 1, 46-57</text></nplcit> described. Particularly preferred oxidizing agents are FeCl₃, N / A₂S₂O₈ and K₂S₂O₈ or mixtures thereof. The polymerization is preferably carried out at a reaction temperature of from -20 to 100.degree. Reaction temperatures of 20 to 100 ° C. are particularly preferred. If necessary, the reaction solution is then treated with at least one ion exchanger.

Suitable solvents for the aforementioned reaction are, for example, polar solvents, for example water, alcohols such as methanol, ethanol, 2-propanol, n-propanol, n-butanol, diacetone alcohol, ethylene glycol, glycerol or mixtures of these. Also suitable are aliphatic ketones such as acetone and methyl ethyl ketone, aliphatic nitriles such as acetonitrile, aliphatic and cyclic amides such as N, N-dimethylacetamide, N, N-dimethylformamide (DMF) and 1-methyl-2-pyrrolidone (NMP), ethers such as tetrahydrofuran ( THF) and sulfoxides such as dimethyl sulfoxide (DMSO) or mixtures of these with one another or with the solvents listed above.

The corresponding monomeric compounds for the preparation of polythiophenes A) containing recurring units of the general formula (I) are known. They can be prepared, for example, by reacting the alkali metal salts of the 3,4-dihydroxythiophene-2,5-dicarboxylic acid esters with the corresponding alkylene dihalides and subsequent decarboxylation of the free 3,4- (alkylenedioxy) thiophene-2,5-dicarboxylic acids (see e.g. B.<nplcit id="ncit0002" npl-type="s"><text>Tetrahedron 1967, 23, 2437-2441</text></nplcit> and <nplcit id="ncit0003" npl-type="s"><text>J. Am. Chem. Soc. 1945, 67, 2217-2218</text></nplcit>).

The resulting polythiophenes are very soluble or dispersible in the polar solvents or solvent mixtures.

In addition to at least one partially fluorinated or perfluorinated polymer C), the formulations according to the invention contain at least one further SO₃^-M⁺- or COO^-M⁺-Group-containing polymer B). Suitable SO₃^-M⁺- or COO^-M⁺Polymers B) containing groups are preferably those which do not contain a fully conjugated main chain, also referred to below as non-conjugated for short. Exemplary for suitable SO₃^-M⁺- or COO^-M⁺Polymers B) containing groups may be polymeric carboxylic acids, such as polyacrylic acids, polymethacrylic acid or polymaleic acids, or polymeric sulfonic acids, such as polystyrene sulfonic acids and polyvinyl sulfonic acids. Copolymers of vinylcarbonic and vinylsulfonic acids with other polymerizable monomers, such as acrylic acid esters and styrene, are also suitable. Polystyrene sulfonic acid, poly (styrene sulfonic acid-co-maleic acid) or poly (vinyl sulfonic acid) are particularly suitable. Very particularly suitable formulations are characterized in that they are at least one SO₃^-M⁺- or COO^-M⁺-Groups containing polymer B) contain polystyrene sulfonic acid (PSS).

These polymers B) are preferred in polar solvents such as water, alcohols such as methanol, ethanol, 2-propanol, n-propanol, n-butanol, diacetone alcohol, ethylene glycol, glycerol, aliphatic ketones such as acetone and methyl ethyl ketone, aliphatic nitriles such as acetonitrile, aliphatic and cyclic amides such as N, N-dimethylacetamide, N, N-dimethylformamide (DMF) and 1-methyl-2-pyrrolidone (NMP), Ethers such as tetrahydrofuran (THF) and sulfoxides such as dimethyl sulfoxide (DMSO) or mixtures containing these, preferably in water, alcohols such as methanol, ethanol, 2-propanol, n-propanol and n-butanol or mixtures of these soluble or dispersible.

Particularly suitable formulations according to the above description are characterized in that they are at least one SO₃^-M⁺- or COO^-M⁺Partially fluorinated or perfluorinated polymer C) containing groups, for example those containing recurring units of the formulas (II-a) and (II-b),<chemistry id="chem0004" num="0004"><img file="EP1564251B1_D0004.tif" /></chemistry>where R_f for a radical with at least one, preferably 1 to 30, repeating unit (s) of the formula (II-c)<chemistry id="chem0005" num="0005"><img file="EP1564251B1_D0005.tif" /></chemistry>stands included. Such perfluorinated polymers are, for example, the polymers commercially available under the trade name Nafion® or in dissolved form under the trade name Liquion®.

In particularly preferred embodiments, the new formulation contains at least one SO₃^-M⁺- or COO^-M⁺-Group-containing polymer C) Nafion® (copolymer of tetrafluoroethylene and the trifluorovinyl ether of poly (hexafluoropropylene oxide) mono (tetrafluorovinyl sulfonic acid) ether).

Formulations which are used as SO₃^-M⁺- or COO^-M⁺-Group-containing polymer B) polystyrene sulfonic acid (PSS) and as SO₃^-M⁺- or COO^-M⁺-Group-containing partially fluorinated or perfluorinated polymer C) Nafion® (copolymer of tetrafluoroethylene and the trifluorovinyl ether of poly (hexafluoropropylene oxide) mono (tetrafluorovinyl sulfonic acid) ether).

The molecular weight of the polyacids is preferably 1,000 to 2,000,000, particularly preferably 2,000 to 500,000. The polyacids or their alkali metal salts are commercially available, for example polystyrene sulfonic acids and polyacrylic acids, or they can be prepared by known processes (see, for example, Houben Weyl, Methods of organic chemistry, Vol. E 20 Macromolecular Substances, Part 2, (1987), p. 1141 uf).

Formulations in which the weight ratio of polythiophene (s) A) to SO are very particularly preferred₃^-M⁺- or COO^-M⁺Group-containing polymer (s) B) from 1 to 2 (1: 2) to 1 to 25 (1:25), preferably from 1 to 2 (1: 2) to 1 to 20 (1:20) is.

Formulations in which the weight ratio of polythiophene (s) A) to SO are particularly preferred₃^-M⁺- or COO^-M⁺-Group-containing, partially fluorinated or perfluorinated (s) polymer (s) C) from 1 to 1 (1: 1) to 1 to 50 (1:50), preferably from 1 to 2 (1: 2 ) is up to 1 in 30 (1:30).

Any combination of the two weight ratios of polythiophene (en) A) to SO described above₃^-M⁺- or COO^-M⁺-Group-containing polymer (s) B) and polythiophene (s) A) to SO₃^-M⁺- or COO^-M⁺-Groups containing (s), partially fluorinated (s) or perfluorinated (n) polymer (s) C) can be realized in the preferred formulations and are hereby considered to be disclosed.

Furthermore, the new formulations can additionally contain at least one polar diluent D) (polar solvent). Within the scope of the invention, polar diluents D) (polar solvents) include diluents with a solubility parameter δ of 16 MPa^1/2 and larger, preferably 19 MPa^1/2 and understand bigger. Solubility parameters are usually measured at standard temperature (20 ° C). For the measurement and calculation of solubility parameters, see J. Brandrup et al., Polymer Handbook, 4^th Ed., 1999, VII / 675 - VII / 688. Solubility parameters are tabulated, e.g. in J. Brandrup et al., Polymer Handbook, 4^th Ed., 1999, VII / 688 - VII / 697. Preferred polar diluents D) are water, alcohols such as methanol, ethanol, 2-propanol, n-propanol, n-butanol, diacetone alcohol, ethylene glycol, glycerol, aliphatic ketones such as acetone and methyl ethyl ketone, aliphatic nitriles such as acetonitrile, aliphatic and cyclic amides such as N. , N-dimethylacetamide, N, N-dimethylformamide (DMF) and 1-methyl-2-pyrrolidone (NMP), ethers such as tetrahydrofuran (THF) and sulfoxides such as dimethyl sulfoxide (DMSO) or mixtures containing them. Particularly preferred polar diluents D) are water, alcohols or mixtures containing them, very particularly preferred are water, methanol, ethanol, n-propanol, 2-propanol or n-butanol or mixtures containing these. In preferred embodiments, the new formulations contain, as polar diluent D), mixtures of water and at least one alcohol.

Such new preferred formulations containing at least one polar diluent D) preferably contain 99.99 to 80% by weight, particularly preferably 99.8 to 95% by weight polar diluent and have a solids content of 0.01 to 20% by weight. %, particularly preferably 0.2 to 5% by weight, ie contain a total of 0.01 to 20% by weight, particularly preferably 0.2 to 5% by weight, of polythiophene (s) A), SO₃^-M⁺- or COO^-M⁺- Group-containing polymer (s) B) and C) and optionally further components, such as binders, crosslinking agents and / or surfactants, in dissolved and / or dispersed form.

The viscosity at 20 ° C. of new preferred formulations containing at least one polar diluent is between the viscosity of the diluent and 200 mPas, preferably &lt;100 mPas.

To set the desired solids content and the required viscosity, the desired amount of diluent can be removed from the formulations by distillation, preferably in vacuo, or by other processes, for example ultrafiltration.

Organic, polymeric binders and / or organic, low molecular weight crosslinking agents or surfactants can also be added to the formulations according to the invention. Appropriate binders are, for example, in<patcit id="pcit0005" dnum="EP564911A"><text>EP-A-564 911</text></patcit> described. Examples include polyvinyl carbazole as binders, silanes, such as Silquest® A187 (from OSi specialties) or surfactants as crosslinking agents, such as the fluorosurfactant FT 248 (Bayer AG).

The formulations can preferably contain small amounts of ionic impurities within the limits set out in <patcit id="pcit0006" dnum="EP991303A"><text>EP-A-991 303</text></patcit> are described. The formulations preferably contain less than 1000 ppm of ionic impurities.

The formulations according to the invention can be prepared in a simple manner. For example, it is possible to use a ready-made mixture containing at least one SO₃^-M⁺- or COO^-M⁺-Group-containing polymer B) and at least one polythiophene A) with at least one partially fluorinated or perfluorinated, SO₃^-M⁺- or COO^-M⁺-Group-containing polymer C) to mix and optionally mix this mixture with at least one diluent, preferably completely or partially to dissolve or disperse in at least one diluent. It is also possible to have at least one ready-made mixture containing an SO₃^-M⁺- or COO^-M⁺Polymer-containing groups B) and at least one polythiophene A) to be mixed beforehand with at least one diluent D), preferably completely or partially dissolved or dispersed in at least one diluent D), at least one SO₃^-M⁺- or COO^-M⁺-Group-containing partially fluorinated or perfluorinated polymer C) in a diluent or to disperse and then to mix the solution (s) and / or dispersion (s). If necessary, the diluent D) or diluent mixture can then be removed in whole or in part from this mixture, for example by distillation or other processes.

The formulations according to the invention are surprisingly suitable for the production of hole-injecting or hole-transporting layers in EL arrangements, organic solar cells, organic laser diodes, organic thin-film transistors or organic field-effect transistors, for the production of electrodes or electrically conductive coatings.

The present invention therefore also relates to the use of the formulations according to the invention for producing hole-injecting layers in EL arrangements, for producing electrodes or electrically conductive coatings.

These EL arrangements are used as display elements ("displays"), e.g. B. in flat screens such as laptops, pagers, mobile phones, navigation devices, car radios, vehicle instrument panels, or as panel lights, such as lamps, illuminated areas, backlighting for LCD displays, signs.

In particular, EL arrangements with a hole-injecting layer containing a formulation according to the invention are distinguished by a high luminosity (luminous intensity) and a significantly longer service life than known EL arrangements.

The present invention therefore also relates to EL arrangements, in particular light-emitting diodes containing a hole-injecting layer and containing a formulation according to the invention. These are preferably such EL arrangements containing at least two electrodes, at least one of which is optionally applied to an optionally transparent substrate, at least one emitter layer between the two electrodes and at least one hole-injecting layer between one of the two electrodes and the emitter layer, thereby characterized in that the hole-injecting layer contains a formulation according to the invention.

In the production of many large-area EL arrangements, for example large-area electroluminescent display elements, it is advantageous if at least one of the electrodes to be supplied with current consists of a transparent and conductive material. Such transparent and conductive electrode materials are, for example<ol id="ol0002" ol-style=""><li>a) metal oxides, for example indium tin oxide (ITO), tin oxide (NESA), doped tin oxide, doped zinc oxide etc.,</li><li>b) semi-transparent metal films, e.g. Au, Pt, Ag, Cu etc.,</li><li>c) semi-transparent, conductive polymers, e.g. polythiophenes, polyanilines, polypyrroles etc.</li></ol>suitable.

An electrode which does not consist of one of the transparent and conductive materials listed above is preferably a metal electrode, in particular a metal cathode.

Suitable materials for metal cathodes are the materials customary for electro-optical structures and are known to the person skilled in the art. Preferred metal cathodes are those made of metals with a low work function such as Mg, Ca, Ba or metal salts such as LiF.

Glass, ultra-thin glass (flexible glass) or plastics, preferably plastic films, are suitable as the optionally transparent substrate.

Particularly suitable plastics for the substrate are: polycarbonates, polyesters such as PET and PEN (polyethylene terephthalate or polyethylene naphthalenedicarboxylate), copolycarbonates, polyacrylate, polysulfone, polyether sulfone (PES), polyimide, polyethylene, polypropylene or cyclic polyolefins or cyclic olefin copolymers (COC), hydrogenated styrene polymers or hydrogenated styrene copolymers.

Suitable polymer substrates can be, for example, films such as polyester films, PES films from Sumitomo or polycarbonate films from Bayer AG (Makrofol®).

An adhesion promoter layer can be located between the substrate and the electrode. Suitable adhesion promoters are, for example, silanes. Epoxysilanes, such as 3-glycidoxypropyltrimethoxysilane (Silquest® A187, from OSi specialties), are preferred. Other adhesion promoters with hydrophilic surface properties can also be used. For example, a thin layer of PEDT: PSS is described as a suitable adhesion promoter for PEDT (<nplcit id="ncit0004" npl-type="s"><text>Hohnholz et al., Chem. Commun. 2001, 2444-2445</text></nplcit>).

At least one emitter material is contained in the emitter layer of the EL arrangement according to the invention. Suitable emitter materials are those which are common for electro-optical structures and are known to the person skilled in the art. Preferred emitter materials are conjugated polymers such as polyphenylene vinylenes and / or polyfluorenes, such as those in, for example<patcit id="pcit0007" dnum="WO9013148A"><text>WO-A 90/13148</text></patcit> described polyparaphenylene vinyl derivatives and polyfluorene derivatives, or emitters from the class of low molecular weight emitters, also referred to in specialist circles as "small molecules", such as aluminum complexes, for example tris (8-hydroxyquinolinato) aluminum (Alq₃), Fluorescent dyes, e.g. quinacridones, or phosphorescent emitters, e.g. Ir (ppy)₃, into consideration. Emitter materials are, for example, in<patcit id="pcit0008" dnum="DE19627071A"><text>DE-A 196 27 071</text></patcit> described.

In addition to the layers listed above, further functional layers can be contained in such an electroluminescent layer structure (EL arrangement), such as, for example, further charge-injecting, for example electron-injecting, charge-transporting or charge-blocking, intermediate layers. Such layer structures are known to the person skilled in the art and are shown, for example, in<nplcit id="ncit0005" npl-type="s"><text>JR Sheats et al., Science 273, (1996), 884</text></nplcit> described. A shift can also take on several tasks. For example, the above-mentioned emitter materials can be used in combination with a hole-transporting intermediate layer between the hole-injecting and emitter layers (cf. for example<patcit id="pcit0009" dnum="US4539507A"><text>US 4,539,507</text></patcit> and <patcit id="pcit0010" dnum="US5150006A"><text>US 5,150,006</text></patcit>).

The basic production of such EL arrangements is known to the person skilled in the art. For example, they can be manufactured in such a way that an electrode is applied to a substrate from solution or dispersion or by vapor deposition. For example, metal oxide or semi-transparent metal film electrodes are preferably applied to the substrate by vapor deposition, while semi-transparent, conductive polymer electrodes are preferably applied to the substrate from solution or dispersion. If necessary, an adhesion promoter - by vapor deposition or from solution or dispersion - can be applied before the electrode material is applied to the substrate. Some of such substrates coated with electrode material are already commercially available (for example K-glass, ITO-coated glass substrates). The hole-injecting layer can then be applied to the electrode, which in the EL arrangements with hole-injecting layer containing a formulation according to the invention advantageously takes place from solution or dispersion. The other layers are then applied to the hole-injecting layer in the order listed above - taking into account that individual layers can be omitted - depending on the material used, from solution or dispersion or by vapor deposition. The layer arrangement is then contacted and encapsulated.

The hole-injecting layer containing a formulation according to the invention is produced by known technologies. For this purpose, a formulation according to the invention - optionally in a solvent - is applied as a film to an electrode, preferably the base electrode. Suitable solvents are the polar diluents listed above, preferably water, alcohols or mixtures of these. Suitable alcohols are, for example Methanol, ethanol, n-propanol, 2-propanol and n-butanol.

The use of these solvents has the advantage that further layers of organic solvents, such as aromatic or aliphatic hydrocarbon mixtures, can be applied without the hole-injecting layer being attacked.

The formulation according to the invention - optionally in a solvent - can be uniformly distributed on the electrode, for example, by printing techniques such as spin coating, casting, knife coating, printing, curtain casting. The layers can then be dried at room temperature or temperatures up to 300 ° C., preferably 100 to 200 ° C.

The formulation according to the invention - optionally in a solvent - can also preferably be applied in a structured manner by techniques such as ink jet. This technique is known to the person skilled in the art and using water-soluble and dispersed polythiophenes such as 3,4-polyethylene dioxythiophene: polystyrene sulfonic acid (PEDT: PSS), for example in<nplcit id="ncit0006" npl-type="s"><text>Science, vol. 279, 1135, 1998</text></nplcit> and <patcit id="pcit0011" dnum="DE19841804A"><text>DE-A 198 41 804</text></patcit> described.

The formulations according to the invention are preferably filtered through a filter, if appropriate in a solvent, before application.

Formulations which can be filtered particularly well for cleaning are obtained, for example, when in solvent D), based on one part by weight of polythiophene (s) containing recurring units of the general formula (I), preferably 1 to 30 parts by weight, particularly preferably 2 to 25 parts by weight of the SO or₃^-M⁺- or COO^-M⁺-Group-containing polymer (s) B) can be used.

The thickness of the hole-injecting layer is, for example, 3 to 500 nm, preferably 10 to 200 nm.

The influence of a hole-injecting layer containing a formulation according to the invention on the properties of the EL arrangement can be tested in a special structure of such an EL arrangement according to the invention. For this purpose, the hole-injecting layer is applied to wet-chemically cleaned ITO substrate using a spin coater. The layer is then dried at 100-200 ° C for 5 min. Depending on the spin speed, the layer thickness is 20-300 nm. A 1% by weight solution of a polyfluorene-based emitter material (Green 1300 LUMATION ™ from Dow Chemical Company) in xylene is spun on as the emitter layer. The thickness of the emitter layer is typically 60-120 nm. Finally, a 5 nm thick Ba layer and then a 200 nm thick Ag layer are evaporated as the cathode. By contacting the indium tin oxide (ITO) anode and the metal cathode, a characteristic line recorder and a calibrated photodiode are used to record current-voltage-luminance characteristics and to measure lifetimes. For this purpose, a constant electrical current or an alternating current is sent through the arrangement, and the voltage and the luminance are tracked as a function of time.

The organic light-emitting diodes according to the invention are distinguished by a long service life, high luminosity, low threshold voltages and a high rectification ratio. Compared to known light-emitting diodes with hole-injecting layers made from a poly (3,4-ethylenedioxythiophene): polystyrene sulfonic acid (PEDT: PSS) dispersion (Baytron® P, HC Starck GmbH) was surprisingly found that the lifetimes of organic light-emitting diodes according to the invention with a hole-injecting layer containing a formulation according to the invention are significantly longer.

<u style="single">Examples</u>

<u style="single">example 1</u>

Preparation of a formulation from poly (3,4-ethylenedioxythiophene) / polystyrene sulfonic acid and a perfluorinated polymer.

40g of a 1.32% poly (3,4-ethylenedioxythiophene) / polystyrene sulfonic acid solution (HC Starck GmbH, Baytron® P test product, TP AI 4083, weight ratio PEDT / PSS 1: 6) are made with 9.96 g a 5.30% by weight solution of Nafion® in a mixture of lower aliphatic alcohols and water (Nafion® perfluorinated ion-exchange resin, 5% by weight solution in lower aliphatic alcohols / H₂O, CAS no. 66796-30-3, Aldrich order no. 27.470-4, measured solids content 5.30% by weight) mixed. The weight ratio of PEDT / PSS / Nafion® is 1: 6: 7.

<u style="single">Example 2</u>

The formulation according to the invention from Example 1 is used to construct an organic light-emitting diode (OLED). The OLED is manufactured as follows:

1.

Preparation of the ITO coated substrate

ITO-coated glass (Merck Balzers AG, FL, Part No. 253 674 XO) is cut into 50 mm x 50 mm pieces (substrates). The ITO layer is coated with conventional photoresist technology and then etched in FeCl₃Solution structured. The isolated ITO strips are 2.0 mm wide. The substrates are then cleaned in a 3% aqueous mucasol solution in an ultrasonic bath for 15 minutes. The substrates are then rinsed with distilled water and spun dry in a centrifuge. This rinsing and drying process is repeated 10 times. Immediately before coating, the ITO-coated sides are cleaned in a UV / ozone reactor (PR-100, UVP Inc., Cambridge, GB) for 10 minutes.

2.

Application of the hole injecting layer

About 10 ml of the formulation according to the invention from Example 1 are filtered (Millipore HV, 0.45 µm). The cleaned ITO-coated substrate is placed on a spin coater and the filtered solution is distributed on the ITO-coated side of the substrate. The excess solution is then spun off by rotating the plate at 800 rpm with the lid closed for a period of 30 s. The substrate coated in this way is then dried on a hot plate at 200 ° C. for 5 minutes. The layer thickness is 85 nm (Tencor, Alphastep 500).

3.

Application of the emitter layer

5 ml of a 1% by weight xylene solution of the emitter Green 1300 LUMATION ™ (Dow Chemical Company) are filtered (Millipore HV, 0.45 μm) and distributed over the dried hole-injecting layer. This and all other process steps are described in pure N₂-Atmospheric carried out (inert gas glove box system, M. Braun, Garching). The hole injection layer is previously dried again in the glove box for 5 min at 200 ° C. The protruding solution of the emitter is then spun off for 30 s by rotating the plate at 400 rpm with the lid closed. The substrate coated in this way is then dried on a hot plate at 130 ° C. for 15 minutes. The total layer thickness is 185 nm.

4.

Application of the metal cathode

A metal electrode is vaporized onto the emitter layer. The substrate is placed with the emitter layer down on a strip mask with strips 2.0 mm wide, which is oriented perpendicular to the ITO strips. Two evaporation boats become p = 10^-3 Pa a 5 nm thick Ba layer and then a 200 nm thick Ag layer evaporated. The evaporation rates are 10 Å / s for Ba and 20 Å / s for Ag. The active illuminated area at the crossing point of the two electrodes is 4 mm².

5.

Encapsulation of the OLEDs

The easily oxidizable cathodes are protected against corrosion by encapsulation. To do this, the polymer layers are removed manually at the edge of the substrate with a scalpel and a metal cap (35mm x 35mm x2mm) is glued on with an epoxy adhesive (UHU Plus, UHU, D) as protection. Moisture absorber (GDO / CA / 18x10x0.4, SAES Getters SpA, Italy) is also placed in the metal cap.

6.

Characterization of the OLED

The two electrodes of the organic LED are connected (contacted) to a voltage source via electrical leads. The positive pole is connected to the ITO electrode, the negative pole is connected to the metal electrode. The dependency of the OLED current and the electroluminescence intensity (detection is carried out with a photodiode (EG&amp;G C30809E)) on the voltage is recorded. The service life is then determined using a constant current of I = 0.32 mA (8 mA / cm²) flows through the arrangement, and the voltage and light intensity are tracked over time.

<u style="single">Comparative Example 2.1</u>

Production of an OLED with poly (3,4-ethylenedioxythiophene) / polystyrene sulfonic acid as a hole-injecting layer:

The procedure is as in Example 2, with the following difference in process step 2:

2.

Application of the hole injection layer

About 10 ml of a 1.3% poly (3,4-ethylenedioxythiophene) / polystyrene sulfonic acid solution (HC Starck GmbH, Baytron® P, TP AI 4083) are filtered (Millipore HV, 0.45 µm). The ITO-coated substrate is then placed on a spin coater and the filtered solution is distributed on the ITO-coated side of the substrate. The supernatant solution is then spun off by rotating the plate at 600 rpm with the lid closed for a period of 30 s. The substrate coated in this way is then dried on a hot plate at 200 ° C. for 5 minutes. The layer thickness is 85 nm.

The metal cathodes according to process step 4 were applied together with the layer structures from example 2 in order to ensure comparability.

Results of the lifetime measurements at constant current (I = 8mA / cm²) the arrangements from Example 2 and Comparative Examples 2.1<tables id="tabl0001" num="0001"><table frame="all"><tgroup cols="5"><colspec colnum="1" colname="col1" colwidth="50mm" /><colspec colnum="2" colname="col2" colwidth="13mm" /><colspec colnum="3" colname="col3" colwidth="22mm" /><colspec colnum="4" colname="col4" colwidth="13mm" /><colspec colnum="5" colname="col5" colwidth="22mm" /><thead valign="top"><row><entry rowsep="0" /><entry namest="col2" nameend="col3" align="left">t = 0</entry><entry namest="col4" nameend="col5" align="left">t = 260h</entry></row><row>&lt;entry /&gt;<entry>U / [V]</entry><entry>L /[rel.unit]</entry><entry>U / [V]</entry><entry>L /[rel.unit]</entry></row></thead><tbody><row><entry>OLED from example 2</entry><entry align="char" char=".">3,66</entry><entry align="char" char="." charoff="29">6,81</entry><entry align="char" char=".">3,88</entry><entry align="char" char="." charoff="29">6,61</entry></row><row><entry>OLED from comparative example 2.1</entry><entry align="char" char=".">3,71</entry><entry align="char" char="." charoff="29">4,66</entry><entry align="char" char=".">4,13</entry><entry align="char" char="." charoff="29">2,59</entry></row></tbody></tgroup></table></tables>

The EL arrangement according to the invention with the hole-injecting layer containing the formulation according to the invention (example 1) is more efficient and has a significantly longer service life than the EL arrangement which is constructed with a hole-injecting layer made of known material (PEDT: PSS from comparative example 2.1) . After a 260-hour long-term test, not only is the decrease in the electroluminescence intensity less, but also the rise in voltage.

<u style="single">Example 3.1:</u>

Preparation of a formulation from poly (3,4-ethylenedioxythiophene) / polystyrene sulfonic acid and a perfluorinated polymer.

15 g of a desalted, 1.36% polyethylene dioxythiophene / polystyrene sulfonic acid solution (HCStarck GmbH, Baytron® P, TP AI 4083 desalinated) with 4.09 g Nafion® solution (Liquion® 1000, 5% wt solution in 2-propanol / H₂O, 1000 Aq, Ion Power Inc., U.S.) mixed. The weight ratio of PEDT / PSS to Nafion® corresponds to 1: 1.

<u style="single">Example 3.2:</u>

Preparation of a formulation from poly (3,4-ethylenedioxythiophene) / polystyrene sulfonic acid and a perfluorinated polymer.

12th g of a desalted, 1.36% polyethylene dioxythiophene / polystyrene sulfonic acid solution (HCStarck GmbH, Baytron® P, TP AI 4083 desalted) are mixed with 3.42 g Nafion® solution (Liquion® 1100, 5% wt solution in 2-propanol / H₂O, 1100 Aq, Ion Power Inc., U.S.) mixed. The weight ratio of PEDT / PSS to Nafion® corresponds to 1: 1.

<u style="single">Example 4.1:</u>

The formulation according to the invention from Example 3.1 is used to construct an organic light-emitting diode (OLED). The OLED is manufactured as in Example 2, with the following difference in process step 2:

2.

Application of the hole injection layer

About 10 ml of the formulation according to the invention from Example 3.1 are filtered (Millipore HV, 0.45 μm). The cleaned ITO-coated substrate is placed on a spin coater and the filtered solution is distributed on the ITO-coated side of the substrate. The excess solution is then spun off by rotating the plate at 800 rpm with the lid closed for a period of 30 s. The substrate coated in this way is then dried on a hot plate at 200 ° C. for 5 minutes. The layer thickness is 85 nm (Tencor, Alphastep 500).

<u style="single">Example 4.2:</u>

The formulation according to the invention from Example 3.2 is used to construct an organic light-emitting diode (OLED). The OLED is manufactured as in Example 2, with the following difference in process step 2:

2.

Application of the hole injection layer

About 10 ml of the formulation according to the invention from Example 3.2 are filtered (Millipore HV, 0.45 µm). The cleaned ITO-coated substrate is placed on a spin coater and the filtered solution is distributed on the ITO-coated side of the substrate. The excess solution is then spun off by rotating the plate at 800 rpm with the lid closed for a period of 30 s. The substrate coated in this way is then dried on a hot plate at 200 ° C. for 5 minutes. The layer thickness is 85 nm (Tencor, Alphastep 500).

<u style="single">Comparative Example 4.3:</u>

Production of an OLED with poly (3,4-ethylenedioxythiophene) / polystyrene sulfonic acid as a hole-injecting layer:

The procedure is as in Example 2, with the following difference in process step 2:

2.

Application of the hole injection layer

About 10 ml of a desalted 1.36% poly (3,4-ethylenedioxythiophene) / polystyrene sulfonic acid solution (HC Starck GmbH, Baytron® P TP AI 4083) are filtered (Millipore HV, 0.45 µm). The ITO-coated substrate is then placed on a spin coater and the filtered solution is distributed on the ITO-coated side of the substrate. The excess solution is then spun off by rotating the plate at 600 rpm with the lid closed for a period of 30 s. The substrate coated in this way is then dried on a hot plate at 200 ° C. for 5 minutes. The layer thickness is 85 nm.

The metal cathodes according to process step 4 were applied together with the layer structures from examples 4.1 and 4.2 in order to ensure comparability.

Results of the lifetime measurements at constant current (I = 24 mA / cm²) the arrangements from Examples 4.1, 4.2 and Comparative Example 4.3:<tables id="tabl0002" num="0002"><table frame="all"><tgroup cols="5"><colspec colnum="1" colname="col1" colwidth="50mm" /><colspec colnum="2" colname="col2" colwidth="13mm" /><colspec colnum="3" colname="col3" colwidth="22mm" /><colspec colnum="4" colname="col4" colwidth="13mm" /><colspec colnum="5" colname="col5" colwidth="22mm" /><thead valign="top"><row><entry rowsep="0" /><entry namest="col2" nameend="col3" align="center">t = 0</entry><entry namest="col4" nameend="col5" align="center">t = 100h h</entry></row><row>&lt;entry /&gt;<entry align="center">U / [V]</entry><entry align="center">L /[rel.unit]</entry><entry align="center">U / [V]</entry><entry align="center">L /[rel.unit]</entry></row></thead><tbody><row><entry align="center">OLED from example 4.1</entry><entry align="char" char=".">4,19</entry><entry align="char" char="." charoff="29">7,58</entry><entry align="char" char=".">4,40</entry><entry align="char" char="." charoff="29">6,95</entry></row><row><entry align="center">OLED from example 4.2</entry><entry align="char" char=".">4,30</entry><entry align="char" char="." charoff="29">7,67</entry><entry align="char" char=".">4,51</entry><entry align="char" char="." charoff="29">7,02</entry></row><row><entry align="center">OLED from comparative example 4.3</entry><entry align="char" char=".">4,02</entry><entry align="char" char="." charoff="29">6,29</entry><entry align="char" char=".">4,43</entry><entry align="char" char="." charoff="29">4,75</entry></row></tbody></tgroup></table></tables>

The EL arrangements according to the invention with the hole-injecting layer containing the formulations according to the invention (Examples 4.1 and 4.2) are more efficient and have a significantly longer service life than the EL arrangement which is built up with a hole-injecting layer made of known material (PEDT: PSS from Comparative Example 4.3) is. After a 100-hour long-term test at a high device current, not only is the decrease in the electroluminescence intensity lower, but also the voltage increase in the EL arrangements according to the invention.