WO2013010661A1

WO2013010661A1 - Sam layers with an htl function

Info

Publication number: WO2013010661A1
Application number: PCT/EP2012/002989
Authority: WO
Inventors: Wilfried LÖVENICH; Timo Meyer-Friedrichsen; Stephan Kirchmeyer; Andreas Elschner
Original assignee: Heraeus Precious Metals GmbH and Co KG
Current assignee: Heraeus Deutschland GmbH and Co KG
Priority date: 2011-07-19
Filing date: 2012-07-16
Publication date: 2013-01-24
Anticipated expiration: 2014-01-19
Also published as: DE102011107921B3; TW201311862A

Abstract

The present invention relates to Ν,Ν,Ν',Ν'-tetraarylbenzidine derivatives of the general formula (I) in which R can in each case be identical or different and in each case represents a hydrogen atom, a halogen atom, or an optionally substituted, straight-chain or branched C₁-C₃₀-alkyl group, Ar can in each case be identical or different and represents an optionally mono- or polysubstituted aryl radical, wherein at least one of the aryl radicals is substituted by at least one radical -R¹-NR²R³, in which R¹ represents a straight-chain or branched C₂-C₂₀-alkylene radical and R² and R³ can be identical or different and in each case represent a hydrogen atom or a C₁-C₅-alkyl group. The invention also relates to a layered body, a process for the production of a layered body, the layered body obtainable by this process, electronic components comprising a layered body and the use of an Ν,Ν,Ν',Ν'-tetraarylbenzidine derivative.

Description

SAM Layers with an HTL Function

The present invention relates to Ν,Ν,Ν',Ν'-tetraarylbenzidine derivatives, a layered body, a process for the production of a layered body, the layered body obtainable by this process, electronic components comprising a layered body and the use of an Ν,Ν,Ν',Ν'-tetraarylbenzidine derivative.

An electroluminescent arrangement (EL arrangement) is characterized in that when an electrical voltage is applied, it emits light with a flow of current. Such arrangements have been known for a long time by the name "light-emitting diodes" (LEDs). The emission of light arises by positive charges (holes) and negative charges (electrons) recombining with the emission of light.

The LEDs customary in the art are all made predominantly of inorganic semiconductor materials. However, EL arrangements of which the essential constituents are organic materials have been known for some years. These organic EL arrangements (OLED = "organic light-emitting diode") as a rule contain one or more layers of organic charge transport compounds.

The main layer configuration of an EL arrangement is e.g. as follows:

1 carrier, substrate

2 anode

3 hole injection layer

4 hole transport layer

5 optionally electron barrier layer 6 emitter layer

7 optionally hole barrier layer

8 electron transport layer

9 electron injection layer

10 cathode

This structure is a particularly detailed case, and can be simplified by omitting individual layers, so that one layer assumes several tasks. In the simplest case, an EL arrangement consists of two electrodes, between which is an organic layer which fulfils all the functions - including the emission of light.

However, it has been found in practice that to increase the luminance, electron and/or hole injection layers are particularly advantageous in the electroluminescent structures, often electrically conductive polymers being employed in particular for the hole injection layer. The dispersions disclosed in EP 0 440 957 A2 of PEDOT with polyanions, such as e.g. polystyrenesulphonic acid (PSS), have acquired particular industrial importance, for example, here. From these dispersions, transparent, conductive films which are suitable as hole injection layers in OLED can be produced, as is described, for example, in EP 1 227 529 A2.

In this context, the polymerization of EDOT is carried out in an aqueous solution of the polyanion, and a polyelectrolyte complex is formed. Cationic polythiophenes which contain polymeric anions as counter-ions for charge compensation are also often called polythiophene/polyanion complexes in the technical field. Due to the polyelectrolyte properties of PEDOT as a polycation and PSS as a polyanion, this complex in this context is not a true solution, but rather a dispersion. The extent to which polymers or parts of the polymers are dissolved or dispersed in this context depends on the weight ratio of the polycation and the polyanion, on the charge density of the polymers, on the salt concentration of the environment and on the nature of the surrounding medium (V. Kabanov, Russian Chemical Reviews 74, 2005, 3-20). The transitions in this context can be fluid. No distinction is therefore made in the following between the terms "dispersed' and "dissolved". Similarly little distinction is made between "dispersing" and "solution" or between "dispersing agent" and "solvent". Rather, these terms are used as being equivalent in the following.

It is known from the prior art to apply bis(l-naphthyl)-N,N'-diphenylbenzidine (NPB) as an electron blocking layer to the hole injection layers comprising PEDOT/PSS described above, this application being carried out by vapour deposition. A disadvantage in this context is, however, that this NPB layer applied by vapour deposition is at least partially detached again when subsequent layers, for example the emitter layer which conventionally follows, are deposited on the NPB layer from solutions.

The present invention was based on the object of overcoming the disadvantages resulting from the prior art in connection with OLEDs, in particular in connection with OLEDs which include hole injection layers comprising conductive polymers, in particular hole injection layers comprising polythiophenes and polyanions functional ized with acid groups.

In particular, the present invention was based on the object of providing compounds which are suitable as a hole transport or electron blocking layer, in particular on a hole injection layer comprising PEDOT/PSS, and which as far as possible are not washed off from this PEDOT/PSS layer when further layers, for example an emitter layer, are deposited on this hole transport or electron blocking layer from aqueous or organic solutions.

The present invention was furthermore based on the object of providing a layered body comprising a hole injection layer and a hole transport and/or electron blocking layer, the hole injection layer comprising conductive polymers, in particular conductive polymers comprising polythiophenes and polyanions functionalized with acid groups. The hole transport and/or electron blocking layer should as far as possible not be washed off from the hole injection layer when further layers, for example an emitter layer, are deposited on this hole transport or electron blocking layer from aqueous or organic solutions.

The present invention was also based on the object of providing a process for the production of a layered body which renders possible the production of hole injection layers comprising conductive polymers, in particular conductive polymers including polythiophenes and polyanions functionalized with acid groups, followed by a hole transport and/or electron blocking layer by means of process measures which are as simple as possible. A contribution towards achieving the abovementioned objects is made by Ν,Ν,Ν',Ν'-tetraarylbenzidine derivatives of the general formula (I)

(I) in which

R can in each case be identical or different and in each case represents a hydrogen atom, a halogen atom, or an optionally substituted, straight-chain or branched Ci-C3o-alkyl group,

Ar can in each case be identical or different and represents an optionally mono- or polysubstituted aryl radical, wherein at least one of the aryl radicals is substituted by at least one radical -R -NR²R³, in which — R¹ represents a straight-chain or branched C₂-C₂₀-alkylene radical, particularly preferably a straight-chain or branched C₃-Ci5-alkylene radical and most preferably a straight-chain or branched C4-C₁₀- alkylene radical and R and R can be identical or different and in each case represent a hydrogen atom or a d-Cs-alkyl group, but particularly preferably a hydrogen atom.

Surprisingly, it has been found that Ν,Ν,Ν',Ν'-tetraarylbenzidine derivatives of the general formula (I) can form a self-assembled monolayer (SAM) on a surface of a conductive polymer, in particular on a surface of a conductive polymer comprising a polythiophene and a polymer functionalized with acid groups, for example on a PEDOT : PSS surface, and an SAM layer of these Ν,Ν,Ν',Ν'- tetraarylbenzidine derivatives can be employed, for example, as a hole transport layer in an OLED.

According to a particular embodiment of the Ν,Ν,Ν',Ν'-tetraarylbenzidine derivatives according to the invention, these have the general formula (II)

in which R⁴ and R⁵ correspond to the radical R, as defined above, with the proviso that at least one of the radicals R⁴ represents a radical -R'-NR²R³, as likewise defined above. These are accordingly preferably N,N'-bis(l-naphthyl)-N,N'- diphenylbenzidine derivatives.

In this connection, according to a particular embodiment of the Ν,Ν,Ν',Ν'- tetraarylbenzidine derivatives according to the invention, it is preferable for these to have the general formula (III)

in which R represents a radical -R -NR R as defined above.

According to another particular embodiment of the Ν,Ν,Ν',Ν'-tetraarylbenzidine derivatives according to the invention, it is preferable for these to have the general formula (IV)

(IV) in which R⁴ represents a radical -R^!-NR²R³ as defined above. In this connection, it is preferable in particular for R¹ to represent a C₂-Ci₀- alkylene group, in particular -(C H_]2)-, and for R and R to represent a hydrogen atom. A contribution towards achieving the abovementioned objects is also made by a layered body comprising at least - a first layer comprising a conductive polymer; a further layer following the first layer, comprising an Ν,Ν,Ν',Ν'- tetraarylbenzidine derivative according to the invention. The layered body according to the invention comprises a first layer which comprises a conductive polymer and which preferably serves as a hole injection layer. Possible conductive polymers in this context are all polymers which have an electrical conductivity, such as, for example, conductive polymers based on optionally substituted polyanilines, optionally substituted polypyrroles or optionally substituted polythiophenes, conductive polymers based on optionally substituted polythiophenes being particularly preferred.

According to a particularly preferred embodiment of the layered body according to the invention, the conductive polymer in the first layer comprises a preferably cationic polythiophene and a preferably anionic polymer functionalized with acid groups.

The polythiophene is preferably a polythiophene with recurring units of the general formula (i) or (ii) or a combination of units of the general formulae (i) and (ii), preferably a polythiophene with recurring units of the general formula (ii)

wherein

A represents an optionally substituted Ci-Cs-alkylene radical,

R represents a linear or branched, optionally substituted Q-ds-alkyl radical, an optionally substituted C₅-C₁₂-cycloalkyl radical, an optionally substituted C₆-C₁₄-aryl radical, an optionally substituted C₇-C₁₈-aralkyl radical, an optionally substituted C₁-C₄-hydroxyalkyl radical or a hydroxyl radical, x represents an integer from 0 to 8 and in the case where several radicals R are bonded to A, these can be identical different.

The general formulae (i) and (ii) are to be understood as meaning that x substituents R can be bonded to the alkylene radical A.

Polythiophenes with recurring units of the general formula (ii) wherein A represents an optionally substituted C₂-C₃-alkylene radical and x represents 0 or 1 are particularly preferred. Poly(3,4-ethylenedioxythiophene), which is optionally substituted, is very particularly preferred as the polythiophene. In the context of the invention, the prefix poly- is to be understood as meaning that the polymer or polythiophene contains more than one identical or different recurring units of the general formulae (i) and (ii). In addition to the recurring units of the general formulae (i) and/or (ii), the polythiophenes can optionally also comprise other recurring units, but it is preferable for at least 50%, particularly preferably at least 75% and most preferably at least 95% of all recurring units of the polythiophene to have the general formula (i) and/or (ii), preferably the general formula (ii). The polythiophenes contain a total of n recurring units of the general formula (i) and/or (ii), preferably of the general formula (ii), wherein n is an integer from 2 to 2,000, preferably 2 to 100. The recurring units of the general formula (i) and/or (ii), preferably of the general formula (ii), can in each case be identical or different within a polythiophene. Polythiophenes with in each case identical recurring units of the general formula (ii) are preferred. The polythiophenes preferably in each case carry H on the end groups.

In the context of the invention, Cj-Cs-alkylene radicals A are preferably methylene, ethylene, n-propylene, n-butylene or n-pentylene. C]-C₁₈-alkyl radicals preferably represent linear or branched Ci-Ci₈-alkyl radicals, such as methyl, ethyl, n- or iso-propyl, n-, iso-, sec- or tert-butyl, n-pentyl, 1 -methyl butyl, 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-Ci₂-cycloalkyl radicals R represent, for example, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl or cyclodecyl, Cs-Cn-aryl radicals R represent, for example, phenyl or naphthyl, and C₇-Ci₈-aralkyl radicals R represent, for example, benzyl, o-, m-, p-tolyl, 2,3-, 2,4-, 2,5-, 2,6-, 3,4-, 3,5- xylyl or mesityl. The preceding list serves to illustrate the invention by way of example and is not to be considered conclusive. In the context of the invention, numerous organic groups are possible optional further substituents of the radicals A and/or of the radicals R, for example alkyl, cycloalkyl, aryl, aralkyl, alkoxy, halogen, ether, thioether, disulphide, sulphoxide, sulphone, sulphonate, amino, aldehyde, keto, carboxylic acid ester, carboxylic acid, carbonate, carboxylate, cyano, alkylsilane and alkoxysilane groups and carboxamide groups.

The polythiophenes can be neutral or cationic. In preferred embodiments they are cationic, "cationic" relating only to the charges on the polythiophene main chain. The polythiophenes can carry positive and negative charges in the structural unit, depending on the substituent on the radicals R, the positive charges being on the polythiophene main chain and the negative charges optionally being on the radicals R substituted by sulphonate or carboxylate groups. In this context, the positive charges of the polythiophene main chain can be partly or completely satisfied by the anionic groups optionally present on the radicals R. Overall, in these cases the polythiophenes can be cationic, neutral or even anionic. Nevertheless, in the context of the invention they are all regarded as cationic polythiophenes, since the positive charges on the polythiophene main chain are the deciding factor. The positive charges are not shown in the formulae, since their precise number and position cannot be determined absolutely. However, the number of positive charges is at least 1 and at most n, where n is the total number of all recurring units (identical or different) within the polythiophene.

For compensation of the positive charge of the polythiophene, the first layer furthermore comprises a polyanion based on polymers functionalized with acid groups. Anions of polymeric carboxylic acids, such as polyacrylic acids, polymethacrylic acid or polymaleic acids, or of polymeric sulphonic acids, such as polystyrenesulphonic acids and polyvinylsulphonic acids, are possible in particular as the polyanion. These polycarboxylic and -sulphonic acids can also be copolymers of vinylcarboxylic and vinylsulphonic acids with other polymerizable monomers, such as acrylic acid esters and styrene. Particularly preferably, the first layer contains an anion of a polymeric carboxylic or sulphonic acid for compensation of the positive charge of the polythiophene.

The anion of polystyrenesulphonic acid (PSS), which, if a polythiophene is used, in particular poly(3,4-ethylenedioxythiophene), is preferably present bonded as a complex in the form of the PEDOT : PSS complexes known from the prior art, is particularly preferred as the polyanion. Such complexes are obtainable by polymerizing the thiophene monomers, preferably 3,4-ethylenedioxythiophene, oxidatively in aqueous solution in the presence of polystyrenesulphonic acid.

The molecular weight of the polymers functionalized with acid groups which supply the polyanions is preferably 1,000 to 2,000,000, particularly preferably 2,000 to 500,000. The polymers functionalized with acid groups or their alkali metal salts are commercially obtainable, e.g. polystyrenesulphonic acids and polyacrylic acids, or can be prepared by known processes (see e.g. Houben Weyl, Methoden der organischen Chemie, vol. E 20 Makromolekulare Stoffe, part 2, (1987), p. 1 141 et seq.).

Polymers functionalized with acid groups (polyanions) and polythiophenes, in particular polystyrenesulphonic acid and poly(3,4-ethylenedioxythiophene), can be present in the first layer in a weight ratio of from 0.5 : 1 to 50 : 1, preferably from 1 : 1 to 30 : 1, particularly preferably 2 : 1 to 20 : 1. The weight of the electrically conductive polymers here corresponds to the weight of the monomers employed for the preparation of the conductive polymers, assuming that complete conversion takes place during the polymerization. According to a particular embodiment of the capacitor according to the invention, the polystyrenesulphonic acid is present in an excess by weight compared with the polythiophene, in particular compared with poly(3,4-ethylenedioxythiophene). According to a preferred embodiment of the layered body according to the invention, the first layer consists of the polythiophene and the polymer functionalized with acid groups, particularly preferably PEDOT : PSS, to the extent of at least 40 wt.%, particularly preferably to the extent of at least 55 wt.% and most preferably to the extent of at least 70 wt.%, in each case based on the total weight of the first layer.

The layer thickness of the first layer is preferably in a range of from 1 nm to 10 μπι, particularly preferably in a range of from 10 nm to 500 nm and most preferably in a range of from 20 nm to 200 nm.

In addition to the first layer described above, the layered body according to the invention comprises a further layer which follows the first layer and comprises the Ν,Ν,Ν',Ν'-tetraarylbenzidine derivative according to the invention described above, it being particularly preferable according to the invention for this further layer to be a layer which forms a self-assembled monolayer (SAM). A self- assembled monolayer in general forms spontaneously when a substrate is immersed in a fluid comprising the Ν,Ν,Ν',Ν'-tetraarylbenzidine derivative. It is an organized layer of amphiphilic molecules, one end of the particular molecules having a specific, reversible affinity for a substrate. In contrast to conventional coating processes, such as, for example, chemical gas phase deposition, SAMs have a defined layer thickness, conventionally a layer thickness in the range of from approximately 0.5 to 3 nm.

A contribution towards achieving the abovementioned objects is also made by a process for the production of a layered body, comprising the process steps i) application of a conductive polymer to a substrate to obtain a first layer; ii) application of an Ν,Ν,Ν',Ν'-tetraarylbenzidine derivative according to the invention.

In process step i) of the process according to the invention, a conductive polymer is applied to a substrate to obtain a first layer.

Possible substrates in this context are all layers which can be employed in electronic components, such as, for example, an OLED. The substrate can thus be in particular a substrate which is provided with a preferably transparent base electrode and is preferably likewise transparent. The transparent substrate which can be employed in this context is glass, PET or other transparent plastics, for example, on to which a transparent electrically conductive electrode, such as e.g. an electrode of indium tin oxide (ITO), doped zinc oxide or tin oxide or a conductive polymer, is then applied. Particularly suitable transparent substrates of plastic are, for example, polycarbonates, polyesters, such as e.g. PET and PEN (polyethylene terephthalate or polyethylene-naphthalene dicarboxylate), copolycarbonates, polyacrylates, polysulphones, polyether sulphones (PES), polyimides, polyethylene, polypropylene, cyclic polyolefins or cyclic olefin copolymers (COC), hydrogenated styrene polymers or hydrogenated styrene copolymers. Suitable polymer substrates can also be, for example, films, such as polyester films, PES films from Sumitomo or polycarbonate films from Bayer AG (Makrofol^®). Glass coated with ITO is particularly preferred according to the invention as the substrate. The conductive polymer is applied to such a substrate or also the electrode layer applied to such a substrate to obtain the first layer of the layered body according to the invention, those conductive polymers which have already been mentioned above as the preferred conductive polymer in connection with the layered body according to the invention being particularly preferred as the conductive polymer. A conductive polymer comprising a polythiophene, particularly preferably PEDOT, and a polymer fiinctionalized with acid groups, particularly preferably PSS, is accordingly particularly preferred according to the invention, here also the use of PEDOT : PSS complexes as the conductive polymer being very particularly preferred.

Preferably, in this context, the conductive polymer is applied to the substrate in the form of a dispersion comprising the conductive polymer and a dispersing agent, particularly preferably in the form of a dispersion comprising a polythiophene, a polymer fiinctionalized with acid groups and a dispersing agent, very particularly preferably in the form of a PEDOT : PSS dispersion, and the dispersing agent is then at least partially removed to obtain the first layer. The application of the dispersions can be carried out, for example, by known processes, e.g. by spin coating, impregnation, pouring, dripping on, spraying, misting, knife coating, brushing or printing, for example ink-jet, screen, gravure, offset or tampon printing, in a wet film thickness of from 0.5 μπι to 250 μπι, preferably in a wet film thickness of from 2 μπι to 50 μπι. The at least partial removal of the dispersing agent is preferably carried out by drying at a temperature in a range of from 20 °C to 200 °C, it possibly being advantageous to at least partially remove the supernatant dispersion from the substrate before the drying process, for example by spinning off.

The preparation of dispersions comprising a polythiophene, a polymer fiinctionalized with acid groups and a dispersing agent is described in principle in EP-A 1 122 274 or US 5, 1 11 ,327. The polymerization of the corresponding monomelic compounds is carried out in the presence of the polymers fiinctionalized with acid groups with suitable oxidizing agents in suitable solvents. Examples of suitable oxidizing agents are iron(III) salts, in particular FeCl₃ und iron(III) salts of aromatic and aliphatic sulphonic acids, H₂0₂, K₂Cr₂0₇, K₂S₂0₈, Na₂S₂0₈, ΚΜη0₄, alkali metal perborates and alkali metal or ammonium persulphates or mixtures of these oxidizing agents. Further suitable oxidizing agents are described, for example, in Handbook of Conducting Polymers (ed. Skotheim, T.A.), Marcel Dekker: New York, 1986, vol. 1, 46-57. Particularly preferred oxidizing agents are FeCl₃, Na₂S₂0₈ and ₂S₂0₈ or mixtures of these. The polymerization is preferably carried out at a reaction temperature of from -20 to 100 °C. Reaction temperatures of from 20 to 100 °C are particularly preferred. If appropriate, the reaction solution is then treated with at least one ion exchanger.

Suitable solvents are e.g. polar solvents, such as, for example, water, alcohols, such as methanol, ethanol, 2-propanol, n-propanol, n-butanol, diacetone alcohol, ethylene glycol, glycerol or mixtures of these. Aliphatic ketones, such as acetone and methyl ethyl ketone, aliphatic nitriles, such as acetonitrile, aliphatic and cyclic amides, such as N,N-dimethylacetamide, Ν,Ν-dimethylformamide (DMF) and 1- methyl-2-pyrrolidone (NMP), ethers, such as tetrahydrofuran (THF), and sulphoxides, such as dimethylsulphoxide (DMSO), or mixtures of these with one another or with the abovementioned solvents are likewise suitable.

Preferably, the dispersions have a solids content in a range of from 0.01 to 20 wt.% and particularly preferably in a range of from 0.2 to 5 wt.%, i.e. they contain in total 0.01 to 20 wt.%, particularly preferably 0.2 to 5 wt.% of polythiophene(s), preferably PEDOT, of polymer functionalized with acid groups, preferably PSS, and optionally further components, such as e.g. binders, crosslinking agents and/or surfactants, in dissolved and/or dispersed form.

The viscosity at 20 °C of the dispersions employed for the preparation of the first layer is preferably between the viscosity of the dispersing agent and 200 mPas, preferably between the viscosity of the dispersing agent and 100 mPas.

To establish the desired solids content and the required viscosity, the desired amount of dispersing agent can be removed from the dispersions by distillation, preferably in vacuo, or by other processes, e.g. ultrafiltration. Organic, polymeric binders and/or organic, low molecular weight crosslinking agents or surfactants can moreover be added to the dispersions. Corresponding binders are described e.g. in EP-A 564 91 1. There may be mentioned here by way of example polyvinylcarbazole, silanes, such as Silquest^® A 187 (OSi Specialities), or surfactants, such as the fluoro-surfactant FT 248 (Bayer AG).

In process step ii) of the process according to the invention, an Ν,Ν,Ν',Ν'- tetraarylbenzidine derivative according to the invention is then applied to the first layer to obtain a further layer, it being particularly preferable for an SAM to be formed on application of the Ν,Ν,Ν',Ν'-tetraarylbenzidine derivative to the first layer in process step ii).

Preferred Ν,Ν,Ν',Ν'-tetraarylbenzidine derivatives in this context are those Ν,Ν,Ν',Ν'-tetraarylbenzidine derivatives which have already been described above as preferred Ν,Ν,Ν',Ν'-tetraarylbenzidine derivatives in connection with the Ν,Ν,Ν',Ν'-tetraarylbenzidine derivative according to the invention. The Ν,Ν'- bis(l-naphthyl)-N,N'-diphenylbenzidine derivatives of the general formula (III) or (IV) are accordingly very particularly preferred in this connection.

The application of the Ν,Ν,Ν',Ν'-tetraarylbenzidine derivatives to the first layer is preferably carried out by a procedure in which the Ν,Ν,Ν',Ν'-tetraarylbenzidine derivatives are dissolved in a suitable, preferably polar solvent, for example water, an alcohol, such as, for example, methanol, ethanol, n-propanol, isopropanol, ethylene glycol or glycerol, a sulphoxide, such as, for example, dimethylsulphoxide, an ester, such as, for example, γ-butyrolactone, methyl acetate or ethyl acetate, an ether, such as, for example, tetrahydrofuran or 1,4- dioxane, a ketone, such as, for example, acetone or methyl ethyl ketone, an amide, such as, for example, formamide, dimethylformamide, N-methylformamide or dimethylacetamide, an aromatic solvent, such as, for example, toluene or chlorobenzene, or a chlorohydrocarbon, such as, for example, chloroform, methylene chloride, 1 ,1, 1-trichloroethane or tetrachloroethene, and the first layer is then coated with the solution obtained in this way, it being possible for the application of the solution to the first layer in turn to be carried out by known processes, e.g. by spin coating, impregnation, pouring, dripping on, spraying, misting, knife coating, brushing or printing, for example ink-jet, screen, gravure, offset or tampon printing. After an action time in a range of from preferably 1 second to 120 minutes, particularly preferably 1 to 15 minutes, at a temperature in a range of from preferably 10 to 60 °C, particularly preferably 20 to 30 °C, an excess of Ν,Ν,Ν',Ν'-tetraarylbenzidine derivative can then optionally be removed, for example, by spinning off the supernatant solution. It may furthermore be advantageous if the coating is also washed once or several times with suitable solvents after the spinning off, in order to ensure that a monolayer of the Ν,Ν,Ν',Ν'-tetraarylbenzidine derivative remains. The process conditions during application of the Ν,Ν,Ν',Ν'-tetraarylbenzidine derivative to the first layer should preferably be chosen such that an SAM layer of the Ν,Ν,Ν',Ν'-tetraarylbenzidine derivative is formed on the first layer comprising the conductive polymer, preferably on the layer comprising PEDOT : PSS. The concentration of Ν,Ν,Ν',Ν'-tetraarylbenzidine derivative in the solution which is employed for application of the Ν,Ν,Ν',Ν'-tetraarylbenzidine derivative to the first layer is preferably in a range of from 0.1 to 20 wt.%, particularly preferably in a range of from 1 to 10 wt.%, in each case based on the total weight of the solution.

In addition to process steps i) and ii), the process according to the invention can comprise further process steps. In particular, if the layered body is a constituent of an OLED, process step ii) can be followed by still further process steps, such as, for example, iii) application of an emitter layer to the hole transport layer; iv) application of an electron injection layer to the emitter layer; v) application of a cathode layer to the electron injection layer. If the first layer of the layered body according to the invention which functions as a hole injection layer or the SAM layer comprising the Ν,Ν,Ν',Ν'- tetraarylbenzidine derivatives which functions as a hole transport layer have an ability to block the electron transport, the hole transport layer or the hole injection layer can also be called an electron blocking layer. If the electron injection layer has the ability to block the hole transport, the electron injection layer can also be called a hole blocking layer.

Suitable materials for the emitter layer are conjugated polymers, such as polyphenylenevinylenes and/or polyfluorenes, for example the polyparaphenylenevinylene derivatives and polyfluorene derivatives described in WO-A-90/13148, or emitters from the class of low molecular weight emitters, also called "small molecules" in technical circles, such as aluminium complexes, such as, for example, tris(8-hydroxyquinolinato)aluminium (Alq₃), fluorescent dyestuffs, e.g. quinacridones, or phosphorescent emitters, such as, for example, Ir(ppy)₃. Further suitable materials for the emitter layer are described e.g. in DE- A-196 27 071. Tris(8-hydroxyquinolinato)aluminium (Alq₃) is particularly preferred according to the invention as the emitter layer.

Individual Ca layers or a stack structure of a Ca layer and another layer which is made of one or more materials chosen from metals of group IA and IIA of the periodic table, excluding Ca, which have an exit work of from 1.5 to 3.0 eV, and oxides, halides and carbonates thereof, are preferred for the electron injection layer. Examples of metals of group IA of the periodic table which have an exit work of from 1.5 to 3.0 eV and of oxides, halides and carbonates thereof are lithium, lithium fluoride, sodium oxide, lithium oxide and lithium carbonate. Examples of metals of group IIA of the periodic table, excluding Ca, which have an exit work of from 1.5 to 3.0 eV and of oxides, halides and carbonates thereof are strontium, magnesium oxide, magnesium fluoride, strontium fluoride, barium fluoride, strontium oxide and magnesium carbonate.

Suitable materials for the cathode layer are, in particular, transparent or translucent materials with a relatively low exit work (of preferably less than 4.0 eV). Examples of such materials are metals, such as, for example, lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), Be, magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), aluminium (Al), scandium (Sc), vanadium (V), Zn, yttrium (Y), indium (In), cerium (Ce), samarium (Sm), Eu, Tb, and ytterbium (Yb); alloys which consist of two or more of these metals; alloys which consist of one or more of these metals and one or more metals which are chosen from Au, Ag, Pt, Cu, manganese (Mn), titanium (Ti), cobalt (Co), nickel (Ni), tungsten (W) and tin (Sn); graphite or graphite intercalation compounds; and metal oxides, such as, for example, ITO and tin oxide. The use of aluminium as the cathode layer is particularly preferred.

The application of the further layers, in particular that of the emitter layer, of the electron injection layer and of the cathode layer, can be carried out by the method and manner known to the person skilled in the art, preferably by vapour deposition, such as is described, for example, in WO-A-2009/0170244.

A contribution towards achieving the abovementioned objects is also made by a layered body, particularly preferably an OLED or an OPV element, which is or are obtainable by the process according to the invention.

A contribution towards achieving the abovementioned objects is also made by an electronic component comprising a layered body according to the invention or a layered body obtainable by the process according to the invention, wherein this component is preferably an OLED or an OPV element, particularly preferably an

OLED.

The layer configuration of the OLED can have all the configurations known to the person skilled in the art, but preferably the layer sequence of hole injection layer/hole transport layer is replaced by the layered body according to the invention such that further layers of Ν,Ν,Ν',Ν'-tetraarylbenzidine derivatives according to the invention, preferably the further SAM layer of Ν,Ν,Ν',Ν'- tetraarylbenzidine derivatives according to the invention, face the emitter layer.

For example, the OLED according to the invention can have any of the following layer configurations (a) to (d) as desired:

(a) anode/

hole injection layer/

hole transport layer/

at least one emitter layer/

cathode; (b) anode/

hole injection layer/

hole transport layer/

at least one emitter layer/

electron injection layer/

cathode;

(c) anode/

hole injection layer/

hole transport layer/

at least one emitter layer/ electron transport layer/

cathode;

(d) anode/

hole injection layer/

hole transport layer/

at least one emitter layer/

electron transport layer/

electron injection layer/

cathode.

In the layer configurations (a) to (d), either an embodiment in which the anode is arranged on the side of the substrate, for example glass or a transparent film of plastic, or an embodiment in which the cathode is arranged on the side of the substrate is used.

Those layers which have already been mentioned above as the preferred anode layer, hole transport layer, emitter layer, electron injection layer or cathode layer in connection with the process according to the invention are in turn preferred as the anode layer, emitter layer, electron injection layer and cathode layer.

The electron transport layer can be made of materials such as, for example, oxadiazole derivatives, anthraquinodimethane or derivatives thereof, benzoquinone or derivatives thereof, naphthoquinone or derivatives thereof, anthraquinone or derivatives thereof, tetracyanoanthraquinodimethane or derivatives thereof, fluorenone derivatives, diphenyldicyanoethylene or derivatives thereof, diphenoquinone derivatives and metal complexes of 8- hydroxyquinoline or derivatives thereof, polyquinoline or derivatives thereof, polyquinoxaline or derivatives thereof or polyfluorene or derivatives thereof. In this context, an OLED which is built up from the following layers is particularly preferred according to the invention: anode layer/first layer of the layered body according to the invention or of the layered body obtainable by the process according to the invention/further layer of the layered body according to the invention or of the layered body obtainable by the process according to the invention/optionally emitter layer/optionally electron injection layer/cathode layer.

A contribution towards achieving the abovementioned objects is also made by the use of the Ν,Ν,Ν',Ν'-tetraarylbenzidine derivatives of the general formula (I) according to the invention, in particular the use of the N,N'-bis(l-naphthyl)-N,N'- diphenylbenzidine derivatives of the general formula (III) or (IV) according to the invention, for the formation of an SAM in an electronic component. The electronic component is preferably an OLED, very particularly preferably an OLED which is built up from the following layers: anode/hole injection layer/layer of the N,N,N',N'-tetraarylbenzidine derivative according to the invention, preferably SAM layer of the Ν,Ν,Ν',Ν'-tetraarylbenzidine derivative according to the invention/emitter layer/electron injection layer/cathode. The hole injection layer preferably comprises a conductive polymer, particularly preferably complexes of PEDOT : PSS.

The invention is now explained in more detail with the aid of non-limiting examples.

Examples

Glass equipment was dried in an oven at 150 °C for one hour, assembled in the hot state and cooled under an inert gas (argon). Unless mentioned otherwise, exclusively anhydrous solvents were used. 1-Bromonaphthalene, 6- bromohexanoyl chloride, aluminium chloride, sodium borohydride, Li₂MnCU solution, magnesium, N-bromosuccinimide, Ν,Ν'-diphenylbenzidine, sodium tert- butylate, bis(dibenzylideneacetone)palladium(0), tri-tert-butylphosphine, potassium phthalimide and hydrazine hydrate were obtained from Sigma- Aldrich Co.

Example 1

4 -Bromo- 1 '-(6-bromohexano)naphthone

9.32 g (45 mmol) of 1 -bromonaphthalene and 7.81 ml (51 mmol) of 6- bromohexanoyl chloride were dissolved in 90 ml of anhydrous 1,2- dichloroethane, and a total of 7.60 g (57 mmol) of aluminium chloride were added in portions in the course of 10 minutes, while cooling with ice. The dark red solution was stirred at 0 °C for one hour and then at room temperature over night. The solution was cooled again to 0 °C and hydrolysed cautiously with 90 ml of 2 M hydrochloric acid. Subsequently extraction was carried out using 3 x 50 ml of methylene chloride. The combined organic phases were washed with water, dried over MgS0₄ and filtered and the solvent was stripped off in vacuo. The crude product obtained (20.5 g) was purified by chromatography (silica gel 60, eluent: toluene). Yield: 10.3 g (60 % of theory); slightly reddish oil with a product content according to GC-MS analysis of 79.5 %. The product was employed in Example 2 without further purification. Example 2

4'-Bromo- 1 '-(6-bromohexano)naphthene

A total of 9.30 g (70 mmol) of aluminium chloride were added to a suspension of 10.3 g (27 mmol) of 4'-bromo-l'-(6-bromohexano)naphthone and 4.80 g (127 mmol) of sodium borohydride in 150 ml of anhydrous THF at 0 °C. The reaction solution was then boiled under reflux for three hours. After cooling, 50 ml of water were added dropwise. 100 ml of ethyl acetate were added to the solution obtained, the organic phase was separated off and the aqueous phase was extracted by shaking with 30 ml of ethyl acetate. The combined organic phases were washed with water, dried over MgS0₄, filtered and concentrated. The crude product was chromatographed over silica gel 60 (eluent toluene : hexane 1 : 9)

(yield: 0.85 g, 10.6 %; colourless oil which crystallizes slowly). Ή NMR (250 MHz, CDC1₃, δ, ppm): 1 .48 (m, 4H), 1.75 (m, 2H), 1.87 (m, 2H), 3.04 (t, 2H, J = 7.7 Hz), 3.40 (t, 2H, J = 6.8 Hz), 7.16 (d, 1H, J = 7.6 Hz), 7.57 (tt, 2H, J = 5.2 Hz, J = 6.8 Hz), 7.69 (d, 1H, J = 7.6 Hz), 8.02 (dd, 1H, J = 2.2 Hz, J = 7.4 Hz), 8.28 (dd, 1H, J= 2.3 Hz, J= 7.4 Hz).

r-(6-Bromohexano)naphthone

A solution of 1-bromonaphthalene (17.73 g, 85.6 mmol) in THF (220 ml) was added dropwise to a suspension of magnesium filings (2.12 g, 87.4 mmol) in THF (20 ml) under reflux. When the addition was complete, boiling was carried out under reflux for another further 2 hours. The Grignard solution obtained was then added dropwise to a solution of 6-bromohexanoyl chloride (13.10 ml, 85.6 mmol) and an Li₂MnCU solution (0.5 M in THF, 4 ml, 2 mmol) in THF (40 ml) at -5 °C in the course of 1 hour. The reaction solution was then stirred at room temperature for 3 hours. Water (400 ml) and MTBE (600 ml) were added to the solution, the organic phase was separated off and the aqueous phase was extracted with MTBE. The combined organic phases were dried over Na₂S0₄ and filtered and the solvent was evaporated. The crude product obtained (24.95 g) was distilled under a high vacuum (0.1 mbar) at a bath temperature of 150 °C. 21.71 g of product (83.1 % of theory) remained in the distillation flask as a slightly brownish oil with a purity according to GC-MS of 94.7 %. 1H NMR (250 MHz, CDC1₃, δ, ppm): 1.56 (m, 2H), 1.81 (m, 2H), 1.91 (dt, 2H, J = 6.84 Hz, J = 9.71 Hz), 3.05 (t, 2H, J = 7.31 Hz), 3.41 (t, 2H, J - 6.79 Hz), 7.53 (m, 3H), 7.83 (dd, 1H, J = 0.98 Hz, J = 7.24 Hz), 7.86 (m, 1H), 7.97 (d, 1H, J= 8.23 Hz), 8.55 (d, 1H, J= 8.61 Hz). Example 4

1 '-(6-Bromohexano)naphthene

Aluminium chloride (12.66 g, 94.9 mmol) was added in portions to a suspension of l-(6-bromohexano)naphthone (9.06 g, 29.7 mmol) and sodium borohydride (6.47 g, 171 mmol) in anhydrous THF (200 ml) at 0-4 °C. Then, heating under reflux was carried out for 3 hours. After cooling, water (100 ml) was slowly metered in. Ethyl acetate (100 ml) was then added, the organic phase was separated off and the aqueous phase was extracted with ethyl acetate (30 ml). The combined organic phases were dried with sodium sulphate and filtered and the solvent was evaporated. The crude product (1 1.07 g) was purified by chromatography (silica gel, eluent: chloroform). Yield: 5.07 g (58.7 % of theory) as a reddish oil. 1H NMR (250 MHz, CDC1₃, 5, ppm): 1.47 (m, 4H), 1.76 (m, 2H), 1.86 (m, 2H), 3.07 (m, 2H), 3.39 (t, 2H, J = 6.83 Hz), 7.30 (d, 1H, J = 6.79 Hz), 7.38 (m, 1H), 7.48 (ddt, 2H, J = 3.60 Hz, J = 6.73 Hz, J = 8.02), 7.70 (d, 1H, J = 8.1 1 Hz), 7.84 (m, 1H), 8.02 (d, 1H, J= 8.35 Hz).

Example 5

4'-Bromo- 1 "-(6-bromohexyl)naphthene

N-Bromosuccinimide (2.93 g, 16.5 mmol) was added in one portion to a solution of r-(6-bromohexyl)naphthene (4.37 g, 15 mmol) in acetonitrile (45 ml). The solution was stirred for 16 hours with exclusion of light. The reaction solution was added to water (100 ml) and extracted with 3 x 50 ml of methylene chloride. The combined organic phases were dried over Na₂S0₄ and filtered and the solvent was evaporated. The crude product obtained (4.08 g, brown oil) was purified by chromatography (silica gel, eluent: hexane). Yield: 2.86 g (51.4 % of theory) as a colourless oil which crystallizes slowly. 1H NMR (250 MHz, DMSO-d₆, 5, ppm): 1.42 (m, 4H), 1.66 (dt, 2H, J = 7.49 Hz, J = 14.76 Hz), 1.80 (m, 2H), 3.04 (m, 2H), 3.52 (t, 2H, J = 6.74 Hz), 7.30 (d, 1H, J = 7.60 Hz), 7.67 (m, 2H), 7.79 (d, 1H, J= 7.65 Hz), 8.15 (m, 2H).

Example 6

N,N'-Diphenyl-N,N'-di-4-(6-bromohexyl)naphthylbenzidine

1.01 g (3 mmol) of N,N'-diphenylbenzidine, 2.80 g (7.6 mmol) of 4'-bromo-l'-(6- bromohexyl)naphthene and 0.43 mg (4.5 mmol) of sodium tert-butylate were suspended in 60 ml of anhydrous toluene and the suspension was degassed and heated under reflux. At 105 °C, a solution of 68 mg (0.1 mmol) of bis(dibenzylideneacetone)palladium(0) and 24 μΐ (0.1 mmol) of tri-tert- butylphosphine in 30 ml of anhydrous toluene was injected. The solution obtained was then stirred at 1 10 °C for 42 hours. After cooling, 100 ml of methylene chloride were added and extraction was carried out using 2 x 50 ml of water. The organic phase was separated off, dried over Na₂S0₄ and filtered and the solvent was evaporated. The crude product obtained in this way was purified by chromatography (silica gel 60, eluent: toluene/hexane 1 : 1). 1.16 g (42 % of theory) of product were obtained as a pale yellow, viscous oil.

1H NMR (400 MHz, CDC1₃, 5, ppm): 8.05 (d, J = 8.4 Hz, 2H), 8.00 (dd, J = 8.5, 0.7 Hz, 2H), 7.47 (ddd, J= 8.4, 6.8, 1.3 Hz, 2H), 7.38 - 7.32 (m, 4H), 7.27 (dt, J = 8.0, 6.4 Hz, 6H), 7.21 - 7.14 (m, 4H), 7.09 - 6.98 (m, 8H), 6.91 (dt, J = 8.3, 1.0 Hz, 2H), 3.41 (t, J = 6.8 Hz, 4H), 3.15 - 2.99 (m, 4H), 1.93 - 1.85 (m, 4H), 1.85 - 1.76 (m, 4H), 1.61 - 1.43 (m, 8H). 0.64 g of the monosubstituted product N,N'-diphenyl-N-(4-(6- bromohexyl)naphthyl)benzidine were furthermore obtained:

1H NMR (400 MHz, CDC1₃, δ, ppm): 8.06 (d, J = 8.5 Hz, 1H), 8.03 (d, J = 8.3 Hz, 1H), 7.54 - 7.45 (m, 4H), 7.41 - 7.34 (m, 4H), 7.30 - 7.22 (m, 6H), 7.17 (dd, J = 7.7, 3.1 Hz, 4H), 7.05 (d, J = 6.5 Hz, 4H), 3.42 (t, J = 6.8 Hz, 2H), 3.10 (t, J = 7.5 Hz, 2H), 1.89 (dd, J = 14.1, 7.0 Hz, 2H), 1.82 (dd, J = 14.9, 7.5 Hz, 2H), 1.66 - 1.44 (m, 4H).

Example 7

N,N'-Diphenyl-N,N'-di-4-(6-aminohexyl)naphthylbenzidine

0.326 g of potassium phthalimide was added to a solution of 0.54 g of Ν,Ν'- diphenyl-N,N'-di-4-(6-bromohexyl)naphthylbenzidine in 15 ml of anhydrous DMF. The solution was stirred at 100 °C for 16 hours. After cooling, the solvent was stripped off in vacuo, water was added to the residue and the residue was filtered off, rinsed with water and dried in vacuo at 40 °C. The intermediate product was suspended in 20 ml of ethylene glycol, 0.165 g of hydrazine hydrate (98 % pure) were added and it was stirred at 175 °C for 18 hours.

After cooling, 30 ml of water were added to the solution and it was extracted several times with chloroform. The combined organic phases were washed with water, dried over Na₂S0₄ and filtered and the solvent was stripped off. 0.14 g (30 % of theory) of product was obtained as a yellow solid. 1H NMR (400 MHz, CDC1₃, δ, ppm): 8.06 (d, J= 8.4 Hz, 2H), 8.02 - 7.96 (m, 2H), 7.47 (ddd, J= 8.4, 6.8, 1.3 Hz, 2H), 7.39 - 7.31 (m, 6H), 7.29 (d, J= 12.3 Hz, 4H), 7.18 (dd, J= 8.6, 7.3 Hz, 4H), 7.10 - 6.99 (m, 8H), 6.91 (t, J = 7.3 Hz, 2H), 3.16 - 2.97 (m, 4H), 2.70 (t, J= 6.7 Hz, 4H), 1.79 (dd, J= 15.2, 7.8 Hz, 4H), 1.47 (d, J= 6.4 Hz, 12H).

Example 8

N,N'-Diphenyl-N-4-(6-bromohexyl)naphthyl-N'-4-naphthylbenzidine

0.64 g (1 mmol) of N,N'-diphenyl-N-4-(6-bromohexyl)naphthylbenzidine was dissolved in 25 ml of anhydrous toluene, and 0.62 g (3 mmol) of 1 - bromonaphthalene and 0.2 g (2.1 mmol) of sodium tert-butylate was added. The solution was degassed and a solution, prepared under argon, of 0.03 g (0.1 mmol) of bis(dibenzylideneacetone)palladium(0) and 0.01 g (0.05 mmol) of tri-tert- butylphosphine in 15 ml of anhydrous toluene was then injected at 1 10 °C. The reaction solution was boiled under reflux for 19.5 h. After cooling, 250 ml of methylene chloride were added and extracted with 2 x 40 ml of water. The organic phase was dried over Na₂S0₄, filtered and concentrated. The crude product obtained was purified by chromatography (silica gel, mobile phase: hexane/toluene 1 : 1). Yield: 202 mg (26 % of theory). 1H NMR (400 MHz, CDC1₃, δ, ppm): 8.05 (d, J = 8.8 Hz, 1H), 8.00 (d, J = 7.8 Hz, 1H), 7.94 (d, J = 8.1 Hz, 1H), 7.88 (d, J = 8.1 Hz, 1H), 7.77 (d, J = 8.3 Hz, 1H), 7.51 - 7.40 (m, 4H), 7.34 (t, J = 13.2 Hz, 8H), 7.18 (dd, J= 7.5, 2.7 Hz, 4H), 7.04 (t, J = 7.6 Hz, 8H), 6.92 (d, J = 6.4 Hz, 2H), 3.42 (t, J = 6.8 Hz, 2H), 3.08 (d, J = 7.7 Hz, 2H), 1.88 (d, J = 7.1 Hz, 2H), 1.82 (d, J = 7.4 Hz, 2H), 1.53 (m, 4H). FD- MS: m/z (%) = 752 (100) [M+l]. Example 9

N,N'-Diphenyl-N-4-(6-aminohexyl)naphthyl-N'-4-naphthylbenzidine

N,N'-Diphenyl-N-4-(6-bromohexyl)naphthyl-N'-4-naphthylbenzidine is reacted in accordance with Example 7 to give the product.

Claims

1. Ν,Ν,Ν',Ν'-Tetraarylbenzidine derivatives of the general formula (I)

in which

R can in each case be identical or different and in each case represents

a hydrogen atom,

a halogen atom, or

an optionally substituted, straight-chain or branched C|-C₃₀- alkyl group,

Ar can in each case be identical or different and represents an optionally mono- or polysubstituted aryl radical, wherein at least one of the aryl radicals is substituted by at least one radical -R¹- NR²R³, in which

R¹ represents a straight-chain or branched C₂-C₂o-alkylene radical and

R² and R³ can be identical or different and in each case represent a hydrogen atom or a Ci-C₅-alkyl group.

Ν,Ν,Ν',Ν'-Tetraarylbenzidine derivatives according to claim 1, having the general formula (II)

3. Ν,Ν,Ν',Ν'-Tetraarylbenzidine derivatives according to claim 1 or 2, having the general formula (III)

(III) in which represents a radical -R^!-NR²R³ as defined in claim 1

Ν,Ν,Ν',Ν'-Tetraarylbenzidine derivatives according to claim 1 or 2, having the general formula (IV)

(IV) in which R⁴ represents a radical -R'-NR²R³ as defined in claim 1 Ν,Ν,Ν',Ν'-Tetraarylbenzidine derivatives according to one of the preceding claims, wherein R represents a C₂-Cio-alkylene group and R and R³ represent a hydrogen atom.

Ν,Ν,Ν',Ν'-Tetraarylbenzidine derivatives according to claim 5, wherein R¹ represents -(CeHn)--

A layered body, comprising at least

a first layer comprising a conductive polymer;

a further layer following the first layer, comprising an Ν,Ν,Ν',Ν'- tetraarylbenzidine derivative as defined in one of claims 1 to 6.

Layered body according to claim 7, wherein the conductive polymer comprises a polythiophene and a polymer functionalized with acid groups.

Layered body according to claim 8, wherein the polythiophene is poly(3,4-ethylenedioxythiophene).

Layered body according to claim 8 or 9, wherein the polymer functionalized with acid groups is a polystyrenesulphonic acid.

Layered body according to one of claims 8 to 10, wherein the weight ratio of polymer functionalized with acid groups to polythiophene in the first layer is in a range of from 0.5 : 1 to 50 : 1.

Layered body according to one of claims 8 to 1 1 , wherein the first layer consists of the polythiophene and the polymer functionalized with acid groups to the extent of at least 50 wt.%, based on the total weight of the first layer.

13. Layered body according to one of claims 7 to 12, wherein the further layer forms an SAM (" self-assembled monolayer" layer). 14. A process for the production of a layered body, comprising at least the process steps

i) application of a conductive polymer to a substrate to obtain a first layer;

ii) application of an Ν,Ν,Ν',Ν'-tetraarylbenzidine derivative of the general formula (I) as defined in one of claims 1 to 6.

15. Process according to claim 14, wherein the conductive polymer comprises a polythiophene and a polymer functionalized with acid groups.

16. Process according to claim 15, wherein the polythiophene is poly(3,4- ethylenedioxythiophene).

17. Process according to claim 15 or 16, wherein the polymer functionalized with acid groups is a polystyrenesulphonic acid.

18. Process according to one of claims 15 to 17, wherein the conductive polymer is applied to the substrate in the form of a dispersion comprising the conductive polymer and a dispersing agent.

19. Process according to claim 18, wherein the dispersion comprises PEDOT : PSS complexes.

20. Process according to one of claims 15 to 19, wherein the weight ratio of polymer functionalized with acid groups to polythiophene in the dispersion is in a range of from 0.5 : 1 to 50 : 1. 21. Process according to one of claims 14 to 20, wherein on application of the Ν,Ν,Ν',Ν'-tetraarylbenzidine derivative to the first layer in process step ii) an SAM is formed.

22. Layered body obtainable by the process according to one of claims 14 to

21.

23. Electronic component comprising a layered body according to one of claims 7 to 13 or 22. 24. Electronic component according to claim 23, wherein the component is an OLED ("organic light-emitting diode") or an OVP element ("organic photovoltaic" element).

25. Electronic component according to claim 24, wherein the OLED is built up from at least the following layers: anode/first layer of the layered body according to one of claims 7 to 13 or 22/further layer of the layered body according to one of claims 7 to 13 or 22/optionally emitter layer/optionally electron injection layer/cathode. 26. Use of an Ν,Ν,Ν',Ν'-tetraarylbenzidine derivative of the general formula

(I) as defined in one of claims 1 to 6 for the formation of an SAM in an electronic component.

27. Use according to claim 26, wherein the electronic component is an

OLED or an OVP element ("organic photovoltaic" element). Use according to claim 27, wherein the OLED is built up from at least the following layers: anode/first layer of the layered body according to one of claims 6 to 13 or 22/further layer of the layered body according to one of claims 6 to 13 or 22/optionally emitter layer/optionally electron injection layer/cathode.