EP4139971A1

EP4139971A1 - Emulsions comprising organic functional materials

Info

Publication number: EP4139971A1
Application number: EP21723139.8A
Authority: EP
Inventors: Gaëlle BÉALLE; Christoph Leonhard; Hsin-Rong Tseng; Manuel HAMBURGER; Margarita Wucherer-Plietker; Yannik HEIN
Original assignee: Merck Patent GmbH
Current assignee: Merck Patent GmbH
Priority date: 2020-04-21
Filing date: 2021-04-16
Publication date: 2023-03-01
Also published as: CN115700058A; WO2021213917A1; KR20230002860A

Abstract

The present invention relates to emulsions comprising organic functional materials, to methods for their preparation, and the use of said formulations for the preparation of electronic and opto-electroinic devices.

Description

Emulsions comprising organic functional materials

The present invention relates, inter alia, to emulsions comprising organic functional materials, to methods for their preparation, and the use of said formulations for the preparation of electronic and opto-electronic devices.

Organic electronics, such as organic light-emitting diodes (OLEDs), organic field-effect transistors (OFETs), organic photovoltaic cells (OPVs), organic light-emitting electro-chemical cells (OLECs), photo detectors, and all polymer integrated electronic circuits, have drawn much attention in the past two decades, because they are versatile in material design, light weight, and suitable for large area application. These organic electronic devices usually comprise a multilayer structure. Hereby it is crucial to deposit the active organic materials on the nano- to mesoscopic scale on a substrate. In addition, the formation of organic multilayer structures has to occur without affecting the underlying layers in an uncontrolled way. The development of cost effective technologies for the mass production of organic electronics will have a decisive role for their competitiveness as compared to current technologies employed. Cost reduction for the mass production is therefore a mandatory prerequisite for the commercial success of organic electronics. In order to achieve this goal solution based deposition methods could provide a solution. However, current technolo gies do not offer a competitive way to adequately prepare multilayered structures for organic electronics, particularly if they comprise small molecules. This is due to the fact that layers that have already been deposited may be, at least in part, dissolved or washed away when another layer is deposited on it.

In the case of OLEDs, the formation of patterned light emitting layers is an important but difficult step in the production of electroluminescent devices. For example, the formation of separate red, green and blue patterned emitter layers is typically required in the production of electroluminescent full color display devices. Vacuum evaporation (e.g., using a shadow mask) is the most common technique to form each of the patterned layers. However, vacuum evaporation techniques have a couple of drawbacks which may significantly inhibit the commercial development of multilayer structures comprising organic materials such as OLEDs. These techniques are rather complex in terms of equipment needed. In particular for large format displays, other methods for manufacturing patterned layers are needed. Methods based on depositing materials from solution are especially desirable for their expected compatibility with large scale device fabrication.

The possible technologies are, for example, ink-jet printing, dip coating, spin coating, letter-press printing, screen printing, doctor blade coating, and slot-die coating etc. Ink-jet printing is particularly preferred as it allows high resolution displays to be prepared. However, all of these technologies suffer from their applicability to a broad spectrum of organic semicon ductors and it is, therefore, highly desirable to find other ways to build a multilayer structure. There are two approaches to do this. The first one is to use a cross-linkable compound, as disclosed in EP 0637899 A1 ; here one first immobilises the first layer by cross linking induced either thermally or by exposure to (UV) light, before the next layer is coated or printed on that. The disadvantage of this approach is one has to introduce the cross- linkable compound in the layer, or even design the cross-linkable functional group in organic functional compounds; and moreover the residual cross- linkable group could also be harmful to the device performance. The second approach is to use so-called orthogonal solvents, e.g, the first layer is insoluble in the solvent of the solution, from which the second layer will be coated. To do so, one has to either have a pair of compounds, which are soluble in orthogonal solvents, or to find a suitable formulation, which fulfils the condition of orthogonal solvents.

One approach is disclosed in WO 2003/050147 A1 to prepare conjugated polymer dispersions from mini-emulsions, where the conjugated polymers are in form of small spherical units called semiconducting polymer nanospheres (SPNs). Miniemulsions are understood to be stable emulsions of droplets with a distinct size between 1 and 5000 nm, made by shearing a system containing a solvent A, a solution (in a solvent B) of a compound insoluble in solvent A, and a small amount of a surfactant, whereby solvent A is immiscible with solvent B. Polymer particles can be obtained from such droplets after evaporation of solvent A. The formulation of conjugated polymers in dispersions, as disclosed in WO 2003/050147 A1 , can be used to build multilayer structures in, e.g. OLEDs and OPVs. The deposition of polymers is known in the prior art.

However, the performance of OLEDs based on small molecules (SMOLEDs) is in most cases much better as compared to OLEDs based on conjugated polymers (PLEDs). PLEDs suffer, for instance, from insufficient lifetime. On the other hand, recently the SMOLEDs have shown excellent performance, in aspects of color, lifetime and driving voltages. Actually, SMOLEDs have already achieved commercial entry into small display market, like mobile phone. In order to overcome the disadvantages of the thermal vacuum deposition which leads to a low material exploitation and to limited device dimension, the present invention relates to a method to formulate organic functional materials, preferably small molecule organic functional materials, in emulsions, preferably mini- or micro-emulsions with droplet sizes in the range from 50 to 500 nm, and dispersions for facilitating the formation of a multilayer structure.

It is therefore highly desired to find a way to formulate and coat organic functional materials, preferably small molecule organic functional materials, on large area, in order to take advantage of their favorable electronic and opto-electronic characteristics without modifying the chemical structure of these compounds.

It is an object of the present invention to overcome the problems known in the prior art. In particular, it is an object of the present invention to provide stable emulsions and dispersions, methods for their preparations and their use for the preparation of electronic and opto-electronic devices with multilayer structure.

Surprisingly, it has been found that stable emulsions and dispersions comprising organic functional materials can be formed. These emulsions and dispersions, commonly referred herein as to formulations, can be employed in order to prepare devices with layer and multilayer structures by using simple deposition techniques from solution. The formulations according to the present invention are particularly important and useful for the preparation of opto-electronic devices such as OLEDs, solar cells, and photovoltaic cells.

The general distinction between emulsion and dispersion is up to the composition of one or more of the discontinuous phases. An emulsion comprises, in addition to organic functional materials as outlined below in the present application, at least one solvent. If the solvent is removed a dispersion is obtained. The discontinuous phase of the formulation can exist in the form of a nanodroplet and nanoparticle in the case of an emulsion and dispersion, respectively. The present invention relates to a formulation, comprising at least one discontinuous phase and at least one continuous phase, wherein the at least one discontinuous phase contains at least one first solvent, wherein the at least one continuous phase contains at least one second organic solvent, wherein the formulation contains at least one surfactant, and wherein the at least one discontinuous phase comprises at least one organic functional material, preferably at least one small molecule organic functional material.

Preferably, the formulation according to the present invention comprises one continuous phase. More preferably, the formulation according to the present invention comprises one continuous phase and one discontinuous phase.

In a preferred embodiment of the present invention the discontinuous phase comprises 1 to 5, more preferably 1 to 4, and most preferably 1 to 3 organic functional materials, preferably small molecule organic functional materials.

In another preferred embodiment of the present invention the formulation comprises 1 to 6, more preferably 2 to 5, and most preferably 2 to 4 organic functional materials, preferably small molecule organic functional materials.

Preferably, the formulation according to the present invention comprises 2 to 5 surfactants, more preferably it comprises 2 or 4 surfactants and most preferably it comprises 2 surfactants. Surfactants are used to stabilise the emulsion.

Surfactants suitable for the present invention include anionic surfactants, nonionic surfactants, cationic surfactants, zwitterionic surfactants, amphoteric surfactants, or combinations thereof. Preferred are nonionic surfactants, preferably 2 to 5 nonionic surfactants, more preferably 2 to 4 nonionic surfactants and most preferably 2 nonionic surfactants. Non-limiting examples of anionic surfactants suitable for use herein include alkyl and alkyl ether sulfates, sulfated monoglycerides, sulfonated olefins, alkyl aryl sulfonates, primary or secondary alkane sulfonates, alkyl sulfosuccinates, acyl taurates, acyl isethionates, alkyl glycerylether sulfonate, sulfonated methyl esters, sulfonated fatty acids, alkyl phosphates, acyl glutamates, acyl sarcosinates, alkyl sulfoacetates, acylated peptides, alkyl ether carboxylates, acyl lactylates, anionic fluorosurfactants, sodium lauroyl glutamate, and combinations thereof.

Anionic surfactants suitable for use according to the present invention include alkyl and alkyl ether sulfates. These materials have the respective formulae ROSO₃M and R0(C₂H₄0)_XS0₃M, wherein R is alkyl or alkenyl of from 8 to 24 carbon atoms, x is 1 to 10, and M is a water-soluble cation such as ammonium, sodium, potassium and triethanolamine. The alkyl ether sulfates are typically made as condensation products of ethylene oxide and monohydric alcohol's having from 8 to 24 carbon atoms.

Preferably, R has from 10 to 18 carbon atoms in both the alkyl and alkyl ether sulfates. The alcohols can be derived from fats, e.g., coconut oil or tallow, or can be synthetic. Lauryl alcohol and straight chain alcohol's derived from coconut oil are preferred herein. Such alcohol's are reacted with 1 to 10, preferably from 3 to 5, and particularly prefereably 3, molar proportions of ethylene oxide and the resulting mixture of molecular species having, for example, an average of 3 moles of ethylene oxide per mole of alcohol, is sulfated and neutralized.

Specific examples of alkyl ether sulfates which may be used according to the present invention are sodium and ammonium salts of coconut alkyl triethylene glycol ether sulfate; tallow alkyl triethylene glycol ether sulfate, and tallow alkyl hexaoxyethylene sulfate. Highly preferred alkyl ether sulfates are those comprising a mixture of individual compounds, said mixture having an average alkyl chain length of from 10 to 16 carbon atoms and an average degree of ethoxylation of from 1 to 4 moles of ethylene oxide.

Preferred anionic surfactants for use according to the present invention include ammonium lauryl sulfate, ammonium laureth sulfate, triethylamine lauryl sulfate, triethylamine laureth sulfate, triethanolamine lauryl sulfate, triethanolamine laureth sulfate, monoethanolamine lauryl sulfate, mono- ethanolamine laureth sulfate, diethanolamine lauryl sulfate, diethanolamine laureth sulfate, lauric monoglyceride sodium sulfate, sodium lauryl sulfate, sodium laureth sulfate, potassium lauryl sulfate, potassium laureth sulfate, sodium lauryl sarcosinate, sodium lauroyl sarcosinate, lauryl sarcosine, cocoyl sarcosine, ammonium cocoyl sulfate, ammonium lauroyl sulfate, sodium cocoyl sulfate, sodium lauroyl sulfate, potassium cocoyl sulfate, potassium lauryl sulfate, triethanolamine lauryl sulfate, triethanolamine lauryl sulfate, monoethanolamine cocoyl sulfate, monoethanolamine lauryl sulfate, sodium dodecyl sulfate, sodium tridecyl benzene sulfonate, sodium dodecyl benzene sulfonate, and combinations thereof.

Particularly preferred anionic surfactants are selected from alkyl sulfates, alkylbenzyl sulfates, alkyl sulfonates, alkylbenzyl sulfonates, alkyl phosphates, alkyl phosphonates, and alkyl carboxylates, particularly preferably sodium deodecyl sulphate (SDS).

Amphoteric surfactants suitable for use according to the present invention include those that are broadly described as derivatives of aliphatic secondary and tertiary amines in which the aliphatic radical can be straight or branched chain and wherein one of the aliphatic substituents contains from 8 to 18 carbon atoms and one contains an anionic water solubilizing group, e.g., carboxy, sulfonate, sulfate, phosphate, or phosphonate. Examples of compounds falling within this definition are sodium 3-dodecyl- aminopropionate, sodium 3-dodecylaminopropane sulfonate, sodium lauryl sarcosinate, N-alkyltaurines such as the one prepared by reacting dodecylamine with sodium isethionate according to the teaching of US 2658072, N-higher alkyl aspartic acids such as those produced according to the teaching of US 2438091 and the products described in US 2528378. Cationic surfactants can also be used according to the present invention. Preferred cationic surfactants are selected from cetyl trimethylammonium bromide (CTAB) and other alkyltrimethylammonium salts, cetylpyridinium chloride (CPC), polyethoxylated tallow amine (POEA), benzalkonium chloride (BAC), and benzethonium chloride (BZT).

Suitable nonionic surfactants for use according to the present invention include those described in McCutcheion's Detergents and Emulsifiers, North American edition (1986), Allured Publishing Corp., and McCutcheion's Functional Materials, North American edition (1992). These nonionic surfactants suitable for use herein include alkyl glucosides, alkyl polyglucosides, polyhydroxy fatty acid amides, alkoxylated fatty acid esters, sucrose esters, amine oxides, and combinations thereof.

Suitable nonionic surfactants for use according to the present invention include condensation products of alkylene oxide groups (hydrophilic in nature) with an organic hydrophobic compound, which may be aliphatic or alkyl aromatic in nature. Preferred classes of nonionic surfactants include:

1 ) polyethylene oxide condensates of alkyl phenols, e.g., the condensation products of alkyl phenols having an alkyl group containing from 6 to 20 carbon atoms in either a straight chain or branched chain configuration, with ethylene oxide, the ethylene oxide being present in amounts equal to from 10 to 60 moles of ethylene oxide per mole of alkyl phenol; 2) nonionic surfactants derived from the condensation of ethylene oxide with the product resulting from the reaction of propylene oxide and ethylene diamine products; 3) condensation products of aliphatic alcohol's having from 8 to 18 carbon atoms, in either straight chain or branched chain configuration, with ethylene oxide, e.g., a coconut alcohol ethylene oxide condensate having from 10 to 30 moles of ethylene oxide per mole of coconut alcohol, the coconut alcohol fraction having from 10 to 14 carbon atoms;

4) long chain tertiary amine oxides;

5) long chain tertiary phosphine oxides;

6) long chain dialkyl sulfoxides containing one short chain alkyl or hydroxy alkyl radical of from 1 to 3 carbon atoms (usually methyl) and one long hydrophobic chain which include alkyl, alkenyl, hydroxy alkyl or keto alkyl radicals containing from 8 to 20 carbon atoms, from 0 to 10 ethylene oxide moieties and from 0 to 1 glyceryl moiety;

7) alkyl polysaccharide (APS) surfactants such as the alkyl polyglyco sides, as described in US 4565647, which have a hydrophobic group with 6 to 30 carbon atoms and polysaccharide (e.g. polyglycoside) as the hydrophilic group, and optionally have a polyalkylene-oxide group joining the hydrophobic and hydrophilic moieties, wherein the alkyl group (i.e. the hydrophobic moiety) can be saturated or unsaturated, branched or unbranched, and unsubstituted or substituted (e.g. with hydroxy or cyclic rings); and

8) polyethylene glycol (PEG) glyceryl fatty esters, such as those of the formula R(0)OCH 2CH(OH)CH₂(OCH₂CH₂)nOH wherein n is from 5 to 200, preferably from 20 to 100, and R is an aliphatic hydrocarbyl having from 8 to 20 carbon atoms. Zwitterionic surfactants suitable for use according to the present invention include those that are broadly described as derivatives of aliphatic quaternary ammonium, phosphonium and sulfonium compounds, in which the aliphatic radicals can be straight or branched chain, and wherein one of the aliphatic substituents contains from 8 to 18 carbon atoms and one contains an anionic group, e.g., carboxy, sulfonate, sulfate, phosphate or phosphonate.

Other zwitterionic surfactants suitable for use herein include betaines, including high alkyl betaines such as coco dimethyl carboxymethyl betaine, cocoamidopropyl betaine, cocobetaine, lauryl amidopropyl betaine, oleyl betaine, lauryl dimethyl carboxymethyl betaine, lauryl dimethyl alpha- carboxyethyl betaine, cetyl dimethyl carboxymethyl betaine, lauryl bis-(2- hydroxyethyl)carboxymethyl betaine, stearyl bis-(2-hydroxypropyl) carboxy- methyl betaine, oleyl dimethyl gamma-carboxypropyl betaine, and lauryl bis-(2-hydroxypropyl)alpha-carboxyethyl betaine. The sulfobetaines may be represented by coco dimethyl sulfopropyl betaine, stearyl dimethyl sulfopropyl betaine, lauryl dimethyl sulfoethyl betaine, lauryl bis-(2-hydroxy- ethyl)sulfopropyl betaine and the like; amidobetaines and amidosulfo- betaines, wherein the RCONH(CH2)3 radical is attached to the nitrogen atom of the betaine are also useful in this invention.

The discontinous phase of the formulations exists preferably in the form of nanodroplets. The size of the nanodroplets in the formulation is adjustable by the type and the amount of the at least one surfactant.

The amount of the at least one surfactant is preferably in the range from 0.1 to 20 wt%, more preferably in the range from 0.2 to 10 wt%, and most preferably in the range from 0.5 to 5 wt%, based on the overall weight of the formulation.

A surfactant usually consists of a hydrophilic head and lipophilic tail. The ratio between the mass of the hydrophilic head and the entire molecule is called HLB (hydrophilic lipophilic balance). It is easily calculate by the following formula: where m is the total mass and mn respectively m/. is the mass of the hydrophilic respectively lipophilic part.

One surfactant has one certain HLB, which characterizes this material. Values below 10 are more lipophilic as they have a bigger lipophilic tail than hydrophilic head. Vice versa do more hydrophilic surfactants have an HLB higher than 10.

Therefore, in a preferred embodiment of the present invention, the formulation comprises 2 to 5 surfactants, more preferably 2 to 4 surfactants and most preferably 2 surfactants, often called surfactant and co surfactant, to adjust the total surfactant HLB over a broad range as intended for a certain solvent system. Preferably the total surfactant HLB of the at least one surfactant in the formulation is in the range from 10 to 19, more preferably in the range from 11 to 18 and most preferably in the range from 12 to 17.

Preferably the formulation according to the present invention is an emulsion, wherein both the at least one continuous phase and the at least one discontinuous phase comprise at least one solvent.

In another preferred embodiment of the present invention the formulation is a dispersion, wherein at least one nanodroplet represents a solid nanoparticle which is dispersed in the continuous phase. The dispersion can be obtained, e.g. by removing the at least one solvent from the discontinuous phase as outlined elsewhere within the present application.

Preferably, the continuous phase comprises at least one first solvent with a high polarity. More preferably, the at least one first solvent is selected from water, alcohol, glycols, preferably diethyleneglycol, ethers and/or glycol ethers. Most preferably, the at least one first solvent is selected from alcohol, glycols, ethers or glycol ethers and water. Particularly preferably the at least one first solvent is selected from water and dithyleneglycol. Preferably, the discontinuous phase comprises at least one second solvent, wherein the at least one second solvent is an organic solvent with a lower polarity as compared to the at least one first solvent. The formulation according to the invention is preferably an oil-in-water emulsion (normal or direct emulsion).

Suitable alcohols are alcohols which are 1) in liquid form at working temperature, and 2) if used together with water as solvent, are miscible with water, preferably having a solubility in water of more than 2 g/l. The said working temperature means the temperature, at which the formulation is prepared, preferably at room temperature. More details on alcohols can be found in textbooks of organic chemistry or suitable handbooks. In a preferred embodiment of the present invention the concentration of the continuous phase in the formulation is in the range from 10 to 99 wt%, more preferably from 20 to 95 wt%, most preferably from 40 to 95 wt%, and particularly preferably from 50 to 95 wt%, based on the total weight of the formulation.

In a further embodiment, the at least one organic solvent can be a mixture of at least two organic solvents, which may comprise 2, 3, 4 or more organic solvents, preferably 2 or 3 and most preferably 2 organic solvents. Suitable organic solvents are preferably organic solvents which include inter alia, ketones, ethers, esters, amides such as di-Ci-2-alkylformamides, sulfur compounds, nitro compounds, hydrocarbons, halogenated hydro carbons (e.g. chlorinated hydrocarbons), aromatic or heteroaromatic hydrocarbons (e.g. naphthalene derivatives) and halogenated aromatic or heteroaromatic hydrocarbons.

Preferably, the organic solvent can be chosen from one of the following groups: substituted and non-substituted aromatic or linear ethers such as 3-phenoxytoluene or anisole; substituted or non-substituted arene derivatives such as cyclohexylbenzene; substituted or non-substituted indanes such as hexamethylindane; substituted and non-substituted aromatic or linear ketones such as dicyclohexylmethanone; substituted and non-substituted heterocycles such as pyrrolidinones, pyridines, pyrazines; other fluorinated or chlorinated aromatic hydrocarbons, substituted or non- substituted naphthalenes such as alkyl substituted naphthalenes, such as 1 -ethyl naphthalene.

Particularly preferred organic solvents are, for example, 1 -ethyl- naphthalene, 2-ethylnaphthalene, 2-propylnaphthalene, 2-(1-methylethyl)- naphthalene, 1-(1-methylethyl)-naphthalene, 2-butylnaphthalene, 1,6- dimethylnaphthalene, 2,2'-dimethylbiphenyl, 3,3^'-dimethylbiphenyl, 1- acetylnaphthalene,1 ,2,3,4-tetramethylbenzene, 1 ,2,3,5-tetramethyl- benzene, 1 ,2,4,5-tetramethylbenzene, 1,2,4-trichlorobenzene, 1,2- dihydronaphthalene, 1 ,2-dimethylnaphthalene, 1 ,3-benzodioxole, 1,3- diisopropylbenzene, 1 ,3-dimethylnaphthalene, 1 ,4-benzodioxane, 1,4- diisopropylbenzene, 1 ,4-dimethylnaphthalene, 1 ,5-dimethyltetralin,

1-benzothiophene, thianaphthalene, 1-bromonaphthalene, 1-chloro- methylnaphthalene, 1-methoxynaphthalene, 1-methylnaphthalene,

2-bromo-3-bromomethylnaphthalene, 2-bromomethyl-naphthalene, 2-bromonaphthalene, 2-ethoxynaphthalene, 2-isopropyl-anisole, 3,5- dimethyl-anisole, 5-methoxyindane, 5-methoxyindole, 5-tert-butyl-m- xylene, 6-methylquinoline, 8-methylquinoline, acetophenone, benzothiazole, benzylacetate, butylphenylether, cyclohexylbenzene, decahydronaphthol, dimethoxytoluene, 3-phenoxytoluene, diphenylether, propiophenone, hexylbenzene, hexamethylindane, isochromane, phenylacetate, veratrol, pyrrolidinone, N, N-dibutylaniline, cyclohexyl hexanoate, menthyl isovalerate, dicyclohexyl methanone, ethyl laurate, ethyl decanoate.

In a further embodiment either said continuous phase and/or said discontinuous phase comprise(s) further additive to reduce the surface tension, or to improve the film formation. The suitable additive can be preferably referred to, e.g. WO 2003/019693 A2.

The formulation according to the present invention can additionally comprise one or more further components like for example surface-active compounds, lubricating agents, wetting agents, dispersing agents, hydrophobing agents, adhesive agents, flow improvers, defoaming agents, deaerators, diluents which may be reactive or non-reactive, auxiliaries, colourants, dyes or pigments, sensitizers, stabilizers, or inhibitors. The at least one organic solvent preferably has a boiling point in the range from 200 to 350°C, more preferably in the range from 225 to 325°C and most preferably in the range from 250 to 300°C.

The term organic functional material refers to organic conductors, organic semiconductors, organic dyes, organic fluorescent compounds, organic phosphorescent compounds, organic photoabsorbing compounds, organic photosensing compounds, organic photo sensitizer and other organic photocactive compounds. The term organic functional material also includes organo-metallic complexes of transition metals, rare earths, lanthanides and actinides.

The organic functional material may be selected from the group consisting of small molecules, polymers, oligomers, dendrimers, blends or mixtures thereof. Preferred as organic functional materials are small molecules.

The term small molecule as used herein is defined as molecule not being a polymer, oligomer, dendrimer, or a blend. In particular, repeating structures are absent in small molecules. The molecular weight of small molecules is typically in the range of polymers with a low number of repeating units, oligomers or less.

The molecular weight of the small molecule is preferably < 3000 g/mol, more preferably < 2000 g/mol, and most preferably < 1500 g/mol. The term small molecule organic functional material as used herein is defined as organic functional material fulfilling the criteria for a small molecule.

The polymers of the present invention preferably have 10 to 10000, more preferably 20 to 5000 and most preferably 50 to 2000 repeating units. Oligomers according to the present invention have preferably 2 to 9 repeating units. The branching index of the polymers and oligomers is between 0 (linear polymer without branching) and 1 (completely branched dendrimer). The term dendrimer as used herein is defined according to M. Fischer et al. in Angew. Chem., Int. Ed. 1999, 38, 885).

The molecular weight (M_w) of the polymers of the present invention is preferably in the range from 10.000 to 2.000.000 g/mol, more preferably in the range from 100.000 to 1.500.000 g/mol, and most preferably in the range from 200.000 to 1.000.000 g/mol. The determination of M_w can be performed according to standard techniques known to the person skilled in the art by employing gel permeation chromatography (GPC) with polystyrene as internal standard, for instance.

A blend is a mixture comprising at least one polymeric, dendrimeric or oligomeric component.

The small molecule organic functional materials do not have polymerisable groups, whose intend is to perform polymerization reactions in the discontinuous phase in order to obtain polymeric, oligomeric or dendrimeric organic functional materials, e.g. Cl, Br, I, O-Tosylat, O-Triflat, O-Mesylat, O-Nonaflat, NH, SiMe_3-nF_n (n = 1 or 2), O S0₂R¹, B(OR¹)₂ ,

-CR¹=C(R¹)₂, C=CH and Sn(R¹)3. The nanodroplets of the present invention are therefore not considered as nanoscopic batch reactors and the small molecule organic functional material is an end product.

According to a further preferred embodiment of the present invention the small molecule organic functional material is insoluble in the continuous phase. Within the meaning of the present invention a material or compound is insoluble in a solvent if its solubility at 25°C is less than 0.4 g/100 ml, preferably less than 0.1 g/100 ml, more preferably less than 0.001 g/100 ml. A formulation, characterized in that the small molecule organic functional material has preferably a molecular weight of < 3000 g/mol, more preferably of < 2000 g/mol, and most preferably of < 1500 g/mol, is also object of the present invention.

In another object of the present invention the formulation, if the formulation is an emulsion, is characterized in that the discontinuous phase forms nanodroplets having an average diameter in the range from 1 to 5000 nm, preferably in the range from 10 to 1000 nm, and more preferably in the range from 20 to 500 nm. A miniemulsion is characterized in that the average diameter of the nanodroplets is in the range between 50 and 500 nm. The term emulsion as used herein refers, depending on the average size of the droplets, to both, emulsions and miniemulsions. In another object of the present invention the formulation, if it is a dispersion, is characterized in that the discontinuous phase forms nanoparticles having an average diameter in the range from 1 to 5000 nm, preferably in the range from 10 to 2000 nm, more preferably in the range from 10 to 500 nm, and in particular preferably in the range from 10 to 300 nm, and most preferably in the range from 10 to 100 nm.

The size and size distribution of nanodroplets and nanoparticles in emulsions and dispersions, respectively, can be measured employing standard techniques known to one skilled in the art. Dynamic light scattering can be used to measure both parameters (Chu, B. Laser Light scattering: Basic Principles and Practice, 2nd Edition. Academic Press (1992)).

The formulations of the present invention may also comprise, in addition to the at least one organic functional material in the discontinuous phase, at least one further organic functional material in the continuous phase. Therefore, a formulation, characterized in that the continuous phase comprises at least one further organic functional material is also subject of the present invention. Preferably the formulation comprises 3, more preferably 2, and most preferably 1 organic functional materials in the continuous phase. The content of the at least one organic functional material in the formulation is preferably in the range from 0.001 to 20 weight-%, more preferably in the range from 0.01 to 10 weight-% and most preferably in the range from 0.1 to 5 weight-%, based on the total weight of the formulation.

Furthermore, the formulation of the present invention has a viscosity preferably in the range from 0.8 to 50 mPas, more preferably in the range from 1 to 40 mPas, and most preferably in the range from 2 to 15 mPas.

The viscosity of the formulations and solvents according to the present invention is measured with a 1° cone-plate rotational rheometer of the type Discovery AR3 (Thermo Scientific). The equipment allows a precise control of the temperature and sheer rate. The measurement of the viscosity is carried out at a temperature of 25.0°C (+/- 0.2°C) and a sheer rate of 500 s ¹. Each sample is measured three times and the obtained measured values are averaged.

The formulation of the present invention has a surface tension preferably in the range from 10 to 70 mN/m, more preferably in the range from 15 to 60 mN/m and most preferably in the range from 20 to 50 mN/m.

The surface tension can be measured using a FTA (First Ten Angstrom) 1000 contact angle goniometer at 20°C. Details of the method are available from First Ten Angstrom as published by Roger P. Woodward, Ph.D. “Surface Tension Measurements Using the Drop Shape Method”. Preferably, the pendant drop method can be used to determine the surface tension. This measurement technique dispenses a drop from a needle in a bulk liquid or gaseous phase. The shape of the drop results from the relationship between the surface-tension, gravity and density differences. Using the pendant drop method, the surface tension is calculated from the shadow image of a pendant drop using http://www.kruss.de/services/ education-theory/glossary/drop-shape-analysis. A commonly used and commercially available high precision drop shape analysis tool, namely FTA1000 from First Ten Angstrom, was used to perform all surface tension measurements. The surface tension is determined by the software FTA1000. All measurements were performed at room temperature which is in the range between 20°C and 25°C. The standard operating procedure includes the determination of the surface tension of each formulation using a fresh disposable drop dispensing system (syringe and needle). Each drop is measured over the duration of one minute with sixty measurements which are later on averaged. For each formulation three drops are measured. The final value is averaged over said measurements. The tool is regularly cross-checked against various liquids having well known surface tensions.

The said organic functional materials are selected from hole injection materials (HIM), hole transport materials (FITM), hole blocking materials (FIBM), electron injection materials (EIM), electron transport materials (ETM), electron blocking materials (EBM), exciton blocking materials (ExBM), host materials, emitter materials, metal complexes, and dyes.

Preferably the said small molecule organic functional materials are selected from hole injection materials (HIM), hole transport materials (FITM), hole blocking materials (FIBM), electron injection materials (EIM), electron transport materials (ETM), electron blocking materials (EBM), exciton blocking materials (ExBM), host materials, emitter materials, and metal complexes.

The said functional materials are selected from hole injection materials (HIM), hole transport materials (FITM), hole blocking materials (FIBM), electron injection materials (EIM), electron transport materials (ETM), electron blocking materials (EBM), exciton blocking materials (ExBM), host materials, emitters, metal complexes, and dyes. Preferably the said functional materials are selected from hole injection materials (HIM), hole transport materials (FITM), hole blocking materials (FIBM), electron injection materials (EIM), electron transport materials (ETM), electron blocking materials (EBM), exciton blocking materials (ExBM), host materials, emitters, and metal complexes. The emitter materials are preferably selected from the class of organic electroluminescent emitter materials as outlined elsewhere within the present application. The dyes are preferably selected from compounds employed in conjunction with organic solar cells or organic photovoltaic cells, or dye-sensitized solar cells as described below.

The organic functional materials according to the present application are often characterized by their molecular frontier orbitals, i.e. the highest occupied molecular orbital (HOMO) (sometimes also referred to as valence band) and the lowest unoccupied molecular orbital (LUMO) (sometimes also referred to as conduction band). The HOMO and LUMO levels are routinely measured (by e.g. XPS=X-ray photoelectron spectroscopy, UPS=ultra-violet photoelectron spectroscopy or CV=cyclovoltammetry) or calculated (by quantum chemical methods such as (time dependent) DFT= density functional theory) which are known to the person skilled in the art. One skilled in the art is also aware of the fact that absolute values of these energy levels significantly depend on the method used. The applicant established a consistent combination method to determine the energy levels of organic semiconductors. The HOMO/LUMO levels of a set of semiconductors (more than 20 different semiconductors) are measured by CV with a reliable evaluation method and also calculated by the DFT of Gaussian 03Wwith the same correction functional, for example B3PW91 and the same basis set, for example 6-31 G(d). The calculated values are then calibrated according to the measured values. Such calibration factor is used for further calculation. The agreement between calculated and measured values is very good. Therefore, the comparison of the energy levels of this application is set on a sound base. The energy gaps or band gaps are obtained by the difference between HOMO and LUMO energy levels.

The formulations according to the present invention may comprise one or more organic functional materials selected from hole injection materials (HIM). A HIM refers to a material or unit capable of facilitating holes (i.e. positive charges) injected from an anode into an organic layer or an anode. Typically, a HIM has a HOMO level comparable to or higher than the work function of the anode, i.e. - 5.3 eV or higher.

The formulations according to the present invention may comprise one or more organic functional materials selected from hole transport materials

(HTM). A HTM refers to a material or unit capable of transporting holes (i.e. positive charges) injected from a hole injecting material or an anode. A HTM has usually a high HOMO, typically higher than -5.4 eV. In many cases, HIM can functions also as HTM, depending on the adjacent layer.

The formulations according to the present invention may comprise one or more organic functional materials selected from hole blocking materials (HBM). A HBM refers to a material which, if deposited adjacent to an emissive layer or a hole transporting layer in a multilayer structure, prevents the holes flowing through. Usually it has a lower HOMO as compared to the HOMO level of the HTM in the adjacent layer. Hole blocking layers are frequently inserted between the light-emitting layer and the electron-transport layer in OLEDs. The formulations according to the present invention may comprise one or more organic functional materials selected from electron injection materials (EIM). An EIM refers to a material capable of facilitating electrons (i.e. negative charges) injected from cathode into an organic layer. The EIM usually has a LUMO level comparable to or lower than the working function of the cathode. Typically, the EIM has a LUMO lower than -2.6 eV.

The formulations according to the present invention may comprise one or more organic functional materials selected from electron transport materials (ETM). An ETM refers to a material capable of transporting electrons (i.e. negative charges) injected from an EIM or a cathode. The ETM has usually a low LUMO, typically lower than -2.7 eV. In many cases, an EIM can serve as ETM as well, depending on the adjacent layer.

The formulations according to the present invention may comprise one or more organic functional materials selected from electron blocking materials (EBM). An EBM refers to a material which, if deposited adjacent to an emissive or electron transporting layer in a multilayer structure, prevents the electron flowing through. Usually it has a higher LUMO as compared to the LUMO of the ETM in the adjacent layer. The formulations according to the present invention may comprise one or more organic functional materials materials selected from exciton blocking materials (ExBM). An ExBM refers to a material which, if deposited adjacent to an emissive layer in a multilayer structure, prevents the excitons diffuse through. ExBM should have either a higher triplet level or singlet level as compared to the emissive layer or other adjacent layer.

The formulations according to the present invention may comprise one or more organic functional materials selected from emitters. The term emitter refers to a material which, upon receiving excitonic energy by any kind of energy transfers from other materials, or by forming an exciton either electrically or optically, undergoes radiative decay to emit light. There are two classes of emitters, fluorescent and phosphorescent emitters. The term fluorescent emitter relates to materials or compounds which undergo a radiative transition from an excited singlet state to its ground. The term phosphorescent emitter, as used herein, relates to luminescent materials or compounds which comprise transition metals. This typically includes materials emitting light caused by spin forbidden transition(s), e.g., transitions from excited triplet states. The term dopant as employed herein is also used for the term emitter or emitter material.

The formulations according to the present invention may comprise one or more organic functional materials selected from host materials. Host materials are usually used in combination with emitter and have, in general, larger energy gaps between the HOMO and the LUMO as compared to emitter materials. In addition, host materials behave either as electron or hole transport material. Host materials can also have both electron and hole transport properties. In case singlet transitions are predominantly responsible for photoluminescence in OLEDs, a maximal overlap between the absorption spectrum of the emitter with the photoluminescence spectrum of the host material is highly desirably. This ensures the energy transfer from the host material to the emitter.

Host material is also called matrix or matrix material, preferably if a host is meant which is used in combination with a phosphorescent emitter in an OLEDs. And for copolymer, comprising emitter unit, the polymer backbone has the same meaning as host.

The formulations according to the present invention may comprise one or more organic functional materials selected from metal complexes.

According to quantum mechanics the transition from excited states with high spin multiplicity, e.g. from excited triplet states, to ground state is forbidden. However, the presence of an heavy atom, for example iridium, osmium, platinum and europium, results in a strong spin-orbit coupling, i.e. the excited singlet and triplet are mixed so that triplet gains some singlet character; and if singlet-triplet mixing yields a radiative decay rate faster than the non-radiative event, then the luminance can be efficient. This kind of emission can be achieved using metal complex, as firstly reported by Baldo et al.; Nature 395, 151-154 (1998). Further metal complexes can also function as efficient and broad-band light absorbing materials or dyes, as for example Ru complex reported by B. O'Regan & M. Graetzel, Nature 353, 737 (1991).

The formulations according to the present invention may comprise one or more organic functional materials selected from dyes. A dye can generally be described as an inorganic or organic substance that absorbs light and, therefore, appears colored. The definition of dyes as light absorbing materials which harvest light in order to transmit the light energy to further materials either as light or in any other kind of converted energy.

Further to HIMs mentioned elsewhere herein, suitable HIMs are phenylenediamine derivatives (US 3615404), arylamine derivatives (US 3567450), amino-substituted chalcone derivatives (US 3526501), styrylanthracene derivatives (JP Showa 54 (1979) 110837), hydrazone derivatives (US 3717462), acylhydrazones, stilbene derivatives (JP Showa 61 (1986) 210363), silazane derivatives (US 4950950), polysilane compounds (JP Heisei 2 (1990) 204996), PVK and other electrically conductive macromolecules, aniline-based copolymers (JP Heisei 2 (1990) 282263), electrically conductive, macromolecular thiophene oligomers (JP

Heisei 1 (1989) 211399), PEDOTPSS (spin-coated polymer), plasma- deposited fluorocarbon polymers (US 6127004, US 6208075,

US 6208077), porphyrin compounds (JP Showa 63 (1988) 2956965,

US 4720432), aromatic tertiary amines and styrylamines (US 4127412), triphenylamines of the benzidine type, triphenylamines of the styrylamine type, and triphenylamines of the diamine type. Arylamine dendrimers can also be used (JP Heisei 8 (1996) 193191), phthalocyanine derivatives, naphthalocyanine derivatives, or butadiene derivatives, are also suitable. Preferably, the HIM is selected from monomeric organic compounds comprising amine, triarylamine, thiophene, carbazole, phthalocyanine, porphyrine and their derivatives.

Particular preference is given to the tertiary aromatic amines (US 2008/0102311 A1), for example N,N’-diphenyl-N,N’-di(3-tolyl)benzidine (= 4,4’-bis[N-3-methylphenyl]-N-phenylamino)biphenyl (NPD) (US 5061569), N,N’-bis(N,N’-diphenyl-4-aminophenyl)-N,N-diphenyl-4,4’- diamino-1 ,1 ’-biphenyl (TPD 232) and 4,4’,4”-tris[3-methylphenyl)phenyl- amino]-triphenylamine (MTDATA) (JP Heisei 4 (1992) 308688) or phthalocyanine derivatives (for example H2Pc, CuPc, CoPc, NiPc, ZnPc, PdPc, FePc, MnPc, CIAIPc, CIGaPc, CllnPc, CISnPc, CI2SiPc, (HO)AIPc, (HO)GaPc, VOPc, TiOPc, MoOPc, GaPc-O-GaPc).

Particular preference is given to the following triarylamine compounds of the Formulae 1 (TPD 232), 2, 3, and 4, which may also be substituted, and further compounds as disclosed in US 7399537 B2, US 2006/0061265 A1 , EP 1661888 B1, and JP 08292586 A. Formula 3 Formula 4 Further compounds suitable as hole injection material are disclosed in

EP 0891121 A1 and EP 1029909 A1. Hole injection layers in general are described in US 2004/0174116.

In principle any FITM known to one skilled in the art can be employed in formulations according to the present invention. Further to FITM mentioned elsewhere herein, FITM is preferably selected from amines, triarylamines, thiophenes, carbazoles, phthalocyanines, porphyrines, isomers and derivatives thereof. FITM is particularly preferably selected from amines, triarylamines, thiophenes, carbazoles, phthalocyanines, and porphyrines.

Suitable materials for hole-transporting layers are phenylenediamine derivatives (US 3615404), arylamine derivatives (US 3567450), amino- substituted chalcone derivatives (US 3526501), styrylanthracene derivatives (JP A 56-46234), polycyclic aromatic compounds (EP 1009041), polyarylalkane derivatives (US 3615402), fluorenone derivatives

(JP A 54-110837), hydrazone derivatives (US 3717462), stilbene derivatives (JP A 61-210363), silazane derivatives (US 4950950), polysilanes (JP A 2-204996), aniline copolymers (JP A 2-282263), thiophene oligomers, polythiophenes, PVK, polypyrroles, polyanilines and further copolymers, porphyrin compounds (JP A 63-2956965), aromatic dimethylidene-type compounds, carbazole compounds, such as, for example, CDBP, CBP, mCP, aromatic tertiary amine and styrylamine compounds (US 4127412), and monomeric triarylamines (US 3180730). Even more triarylamino groups may also be present in the molecule.

Preference is given to aromatic tertiary amines containing at least two tertiary amine units (US 4720432 and US 5061569), such as, for example, 4,4’-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPD) (US 5061569) or MTDATA (JP A 4-308688), N,N,N’,N’-tetra(4-biphenyl)diaminobiphenylene (TBDB), 1 ,1-bis(4-di-p-tolylaminophenyl)cyclohexane (TAPC), 1 ,1-bis(4-di- p-tolylaminophenyl)-3-phenylpropane (TAPPP), 1 ,4-bis[2-[4-[N,N-di(p- tolyl)amino]phenyl]vinyl]benzene (BDTAPVB), N,N,N’,N’-tetra-p-tolyl-4,4’- diaminobiphenyl (TTB), TPD, N,N,N’,N’-tetraphenyl-4,4”’-diamino- 1 ,1’:4’,1”:4”,1”’-quaterphenyl, likewise tertiary amines containing carbazole units, such as, for example, 4 (9FI-carbazol-9-yl)-N,N-bis[4-(9FI-carbazol-9- yl)phenyl]benzeneamine (TCTA). Preference is likewise given to hexa- azatriphenylene compounds in accordance with US 2007/0092755 A1.

Particular preference is given to the following triarylamine compounds of the Formulae 5 to 10, which may also be substituted, and as disclosed in EP 1162193 B1, EP 650955 B1, Synth. Metals 1997, 91(1-3), 209,

DE 19646119 A1 , WO 2006/122630 A1 , EP 1860097 A1 , EP 1834945 A1 , JP 08053397 A, US 6251531 B1 , and WO 2009/041635 A1.

Formula 5 Formula 6 In principle any HBM known to one skilled in the art can be employed in formulations according to the present invention. Further to FIBM mentioned elsewhere herein, suitable hole-blocking materials are metal complexes (US 2003/0068528), such as, for example, bis(2-methyl-8-quinolinolato)(4- phenylphenolato)-aluminium(lll) (BAIQ). Fac-tris(1 -phenylpyrazolato- N,C2)iridium(lll) (lr(ppz)3) is likewise used for this purpose (US 2003/0175553 A1). Phenanthroline derivatives, such as, for example, BCP, or phthalimides, such as, for example, TMPP, are likewise employed.

Further, suitable hole-blocking materials are described in WO 00/70655 A2, WO 01/41512 and WO 01/93642 A1.

In principle any EIM known to one skilled in the art can be employed in formulations according to the present invention. Further to EIM mentioned elsewhere herein, suitable EIM elsewhere herein, EIMs, which comprises at least one organic compound selected from metal complexes of 8- hydroxyquinoline, heterocyclic organic compounds, fluorenones, fluorenylidene methane, perylenetetracarboxylic acid, anthraquinone dimethanes, diphenoquinones, anthrones, anthraquinonediethylene- diamines, isomers and derivates thereof can be used according to the invention. Metal complexes of 8 hydroxyquinoline, such as, for example, Alq3 and

Gaq3, can be used as EIM for electron-injection layers. A reducing doping with alkali metals or alkaline-earth metals, such as, for example, Li, Cs, Ca or Mg, at the interface to the cathode is advantageous. Preference is given to combinations which include Cs, for example Cs and Na, Cs and K, Cs and Rb or Cs, Na and K.

Heterocyclic organic compounds, such as, for example, 1,10- phenanthroline derivatives, benzimidazoles, thiopyran dioxides, oxazoles, triazoles, imidazoles or oxadiazoles, are likewise suitable. Examples of suitable five-membered rings containing nitrogen are oxazoles, thiazoles, oxadiazoles, thiadiazoles, triazoles, and compounds which are disclosed in US 2008/0102311 A1.

Preferred EIMs are selected from compounds of the Formulae 11 to 13, which may be substituted or unsubstituted.

Organic compounds, such as fluorenones, fluorenylidene methane, perylenetetracarboxylic acid, anthraquinone dimethanes, diphenoquinones, anthrones and anthraquinonediethylenediamines, can also be employed, for example In principle any ETM known to one skilled in the art can be employed in formulations according to the present invention. Further to ETM mentioned elsewhere herein, suitable ETM is selected from the group consisting of imidazoles, pyridines, pyrimidines, pyridazines, pyrazines, oxadiazoles, chinolines, chinoxalines, anthracenes, benzanthracenes, pyrenes, pery- lenes, benzimidazoles, triazines, ketones, phosphinoxides, phenazines, phenanthrolines, triarylboranes, isomers and derivatives thereof.

Suitable ETMs for electron-transporting layers are metal chelates of 8 hydroxyquinoline (for example Liq, Alq3, Gaq3, Mgq2, Znq2, Inq3, Zrq4),

Balq, 4 azaphenanthrene-5-ol/Be complexes (US 5529853 A; e.g. Formula 16), butadiene derivatives (US 4356429), heterocyclic optical brighteners (US 4539507), benzazoles, such as, for example, 1 ,3,5-tris(2-N-phenyl- benzimidazolyl)benzene (TPBI) (US 5766779, Formula 17), 1 ,3,5-triazines, pyrenes, anthracenes, tetracenes, fluorenes, spirobifluorenes, dendrimers, tetracenes, for example rubrene derivatives, 1 ,10-phenanthroline derivatives (JP 2003/115387, JP 2004/311184, JP 2001/267080,

WO 2002/043449), silacyl-cyclopentadiene derivatives (EP 1480280,

EP 1478032, EP 1469533), pyridine derivatives (JP 2004/200162 Kodak), phenanthrolines, for example BCP and Bphen, also a number of phenanthrolines bonded via biphenyl or other aromatic groups (US 2007/0252517 A1) or phenanthrolines bonded to anthracene (US 2007/0122656 A1, e.g. Formulae 18 and 19), 1,3,4-oxadiazoles, for example Formula 20, triazoles, for example Formula 21, triarylboranes, for example also with Si (e.g. Formula 48), benzimidazole derivatives and other N heterocyclic compounds (cf. US 2007/0273272 A1), silacyclopenta- diene derivatives, borane derivatives, Ga oxinoid complexes. Preference is given to 2,9,10-substituted anthracenes (with 1- or2- naphthyl and 4- or 3-biphenyl) or molecules which contain two anthracene units (US 2008/0193796 A1 ).

Preference is likewise given to anthracene-benzimidazole derivatives, such as, for example, the compounds of Formulae 22 to 24, and as disclosed in, e.g., US 6878469 B2, US 2006/147747 A, and EP 1551206 A1. In principle any EBM known to one skilled in the art can be employed in formulations according to the present invention. Further to EBM mentioned elsewhere herein, transition-metal complexes, such as, for example, lr(ppz)3 (US 2003/0175553) can be employed as materials for an electron blocking layer.

Preferably, the EBM is further selected from amines, triarylamines and their derivatives.

It is known to a person skilled in the art that the selection of ExBMs suitable for formulations according to the present invention depends on the energy gap of the adjacent layer. Suitable ExBMs are supposed to have a bigger energy gap, either singlet or triplet than the functional material in the adjacent layer which is preferably an emissive layer. Further to ExBMs mentioned elsewhere herein, substituted triarylamines, such as, for example, MTDATA or 4,4’,4”-tris(N,N-diphenylamino)triphenylamine (TDATA), can be used as ExBM for electron-blocking layers. Substituted triarylamines are described, for example, in US 2007/0134514 A1.

N-substituted carbazole compounds, such as, for example, TCTA, or heterocycles, such as, for example, BCP, are also suitable. Metal complexes, such as, for example, lr(ppz)3 or Alq3, can likewise be used for this purpose.

In principle any host material known to one skilled in the art can be employed in formulations according to the present invention. Depending on the kind of emitter employed host materials can be separated into two categories, hosts for fluorescent emitter and hosts for phosphorescent emitter, whereby the latter is often referred to as matrix or matrix material. Formulations according to the present invention may also comprise more than one host material, preferably it comprises 3 host materials, more preferably it comprises 2 host materials, and most preferably it comprises one host material. If a formulation according to the present invention comprises at least two host materials, the host materials are also referred to as co-host or co-host materials.

Preferred host materials suitable for fluorescent emitter are selected from anthracenes, benzanthracenes, indenofluorenes, fluorenes, spirobi- fluorenes, phenanthrenes, dehydrophenanthrenes, thiophenes, triazines, imidazole and derivatives thereof.

Particularly preferred host materials for fluorescent emitter are selected from the classes of the oligoarylenes (for example 2,2‘,7,7‘-tetraphenyl- spirobifluorene in accordance with EP 676461 or dinaphthylanthracene), in particular the oligoarylenes containing condensed aromatic groups, such as, for example, phenanthrene, tetracene, coronene, chrysene, fluorene, spirofluorene, perylene, phthaloperylene, naphthaloperylene, decacyclene, rubrene, the oligoarylenevinylenes (for example 4,4’-bis(2,2- diphenylethenyl)-1 ,1 ’-biphenyl (DPVBi) or 4,4-bis-2,2-diphenylvinyl-1 ,1- spirobiphenyl (spiro-DPVBi) in accordance with EP 676461), the polypodal metal complexes (for example in accordance with WO 2004/081017), in particular metal complexes of 8 hydroxyquinoline, for example aluminium(lll) tris(8-hydroxyquinoline) (aluminium quinolate, Alq3) or bis(2- methyl-8-quinolinolato)-4-(phenylphenolinolato)aluminium, also with imidazole chelate (US 2007/0092753 A1) and quinoline-metal complexes, aminoquinoline-metal complexes, benzoquinoline-metal complexes, the hole-conducting compounds (for example in accordance with WO 2004/058911), the electron-conducting compounds, in particular ketones, phosphine oxides, sulfoxides, etc. (for example in accordance with WO 2005/084081 and WO 2005/084082), the atropisomers (for example in accordance with WO 2006/048268), the boronic acid derivatives (for example in accordance with WO 2006/117052) or the benzanthracenes (e.g. DE 102007024850). Particularly preferred host materials are selected from the classes of the oligoarylenes, containing naphthalene, anthracene, benzanthracene and/or pyrene, or atropisomers of these compounds, the ketones, the phosphine oxides and the sulfoxides. Very particularly preferred host materials are selected from the classes of the oligoarylenes, containing anthracene, benzanthracene and/or pyrene, or atropisomers of these compounds. For the purposes of the present application, an oligoarylene is intended to be taken to mean a compound in which at least three aryl or arylene groups are bonded to one another.

Further preferred host materials for fluorescent emitter are selected, in particular, from compounds of the Formula 25

Ar⁴-(Ar⁵)p-Ar⁶ Formula 25 wherein Ar⁴, Ar⁵, Ar⁶ are on each occurrence, identically or differently, an aryl or heteroaryl group having 5 to 30 aromatic ring atoms, which may be substituted by one or more radicals and p is 1, 2, or 3, the sum of the tt-electrons in Ar⁴, Ar⁵ and Ar⁶ is at least 30 if p = 1 and is at least 36 if p = 2 and is at least 42 if p = 3.

It is particularly preferred in the host materials of the Formula 25 for the group Ar⁵ to stand for anthracene, which may be substituted by one or more radicals R¹, and for the groups Ar⁴ and Ar⁶ to be bonded in the 9 and 10-positions. Very particularly preferably, at least one of the groups Ar⁴ and/or Ar⁶ is a condensed aryl group selected from 1- or 2-naphthyl, 2-, 3- or 9-phenanthrenyl or 2-, 3-, 4-, 5-, 6- or 7-benzanthracenyl, each of which may be substituted by one or more radicals R¹. Anthracene-based compounds are described in US 2007/0092753 A1 and US 2007/0252517 A1, for example 2-(4-methylphenyl)-9,10-di-(2-naphthyl)anthracene, 9-(2- naphthyl)-10-(1 ,1’-biphenyl)anthracene and 9, 10-bis[4-(2,2- diphenylethenyl)phenyl]anthracene, 9, 10-diphenylanthracene, 9, 10- bis(phenylethynyl)anthracene and 1 ,4-bis(9’-ethynylanthracenyl)benzene. Preference is also given to host materials containing two anthracene units (US 2008/0193796 A1 ), for example 10, 10’-bis[1 , 1’ ,4’, 1 ”]terphenyl-2-yl- 9,9’-bisanthracenyl.

Further preferred host materials are derivatives of arylamine, styrylamine, fluorescein, perynone, phthaloperynone, naphthaloperynone, diphenylbutadiene, tetraphenylbutadiene, cyclopentadienes, tetraphenylcyclopentadiene, pentaphenylcyclopentadiene, coumarine, oxadiazole, bisbenzoxazoline, oxazone, pyridine, pyrazine, imine, benzothiazole, benzoxazole, benzimidazole (US 2007/0092753 A1), for example 2,2’,2”-(1 ,3,5-phenylene)tris[1 -phenyl-1 H-benzimidazole], aldazines, stilbene, styrylarylene derivatives, for example 9, 10-bis[4-(2,2- diphenylethenyl)phenyl]anthracene, and distyrylarylene derivatives (US 5121029), diphenylethylene, vinylanthracene, diaminocarbazole, pyran, thiopyran, diketopyrrolopyrrole, polymethine, mellocyanine, acridone, quinacridone, cinnamic acid esters and fluorescent dyes.

Particular preference is given to derivatives of arylamine and styrylamine, for example 4,4’-bis[N-(1-naphthyl)-N-(2-naphthyl)amino]biphenyl (TNB). Preferred compounds with oligoarylene as hosts for fluorescent emitter are compounds as disclosed in, e.g., US 2003/0027016 A1 , US 7326371 B2, US 2006/043858 A, US 7326371 B2, US 2003/0027016 A1 ,

WO 2007/114358, WO 2008/145239, JP 3148176 B2, EP 1009044,

US 2004/018383, WO 2005/061656 A1 , EP 0681019B1, WO 2004/013073A1 , US 5077142, WO 2007/065678, and US 2007/0205412 A1. Particularly preferred oligoarylene-based compounds are compounds of the Formulae 26 to 32.

Further host materials for fluorescent emitter can be selected from spirobifluorene and derivates thereof, for example Spiro-DPVBi as disclosed in EP 0676461 and indenofluorene as disclosed in US 6562485. The preferred host materials for phosphorescent emitter, i.e. matrix materials, are selected from ketones, carbazoles, triarylamines, indenofluorenes, fluorenes, spirobifluorenes, phenathrenes, dehydrophenanthrenes, thiophenes, triazines, imidazoles and their derivatives. Some preferred derivatives are described below in more detail.

If a phosphorescent emitter is employed, e.g. as electroluminescent component in organic light emitting diodes (OLEDs), the host material must fulfil rather characteristics as compared to host materials used for fluorescent emitter. The host materials used for phosphorescent emitter are required to have a triplet level which is higher in energy as compared to the triplet level of the emitter. The host material can either transport electrons or holes or both of them. In addition, the emitter is supposed to have large spin-orbital coupling constants in order to facilitate singlet-triplet mixing sufficiently. This can be enabled by using metal complexes.

Preferred matrix materials are N,N-biscarbazolylbiphenyl (CBP), carbazole derivatives (for example in accordance with WO 2005/039246, US 2005/0069729, JP 2004/288381 , EP 1205527 or DE 102007002714), azacarbazoles (for example in accordance with EP 1617710, EP 1617711, EP 1731584, JP 2005/347160), ketones (for example in accordance with WO 2004/093207), phosphine oxides, sulfoxides and sulfones (for example in accordance with WO 2005/003253), oligophenylenes, aromatic amines (for example in accordance with US 2005/0069729), bipolar matrix materials (for example in accordance with WO 2007/137725), silanes (for example in accordance with WO 2005/111172), 9,9-diarylfluorene derivatives (e.g. in accordance with DE 102008017591), azaboroles or boronic esters (for example in accordance with WO 2006/117052), triazole derivatives, oxazoles and oxazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, distyrylpyrazine derivatives, thiopyran dioxide derivatives, phenylene- diamine derivatives, tertiary aromatic amines, styrylamines, indoles, anthrone derivatives, fluorenone derivatives, fluorenylidenemethane derivatives, hydrazone derivatives, silazane derivatives, aromatic dimethyl- idene compounds, porphyrin compounds, carbodiimide derivatives, diphenylquinone derivatives, phthalocyanine derivatives, metal complexes of 8 hydroxyquinoline derivatives, such as, for example, Alq3, the 8 hydroxyquinoline complexes may also contain triarylaminophenol ligands (US 2007/0134514 A1), various metal complex-polysilane compounds with metal phthalocyanine, benzoxazole or benzothiazole as ligand, hole conducting polymers, such as, for example, poly(N-vinylcarbazole) (PVK), aniline copolymers, thiophene oligomers, polythiophenes, polythiophene derivatives, polyphenylene derivatives, polyfluorene derivatives. Further particularly preferred matrix materials are selected from compounds comprising indolocarbazoles and their derivatives (e.g. Formulae 33 to 39), as disclosed for examples in DE 102009023155.2, EP 0906947B1 , EP 0908787B1, EP 906948B1 , WO 2008/056746A1 , WO 2007/063754A1 , WO 2008/146839A1 , and WO 2008/149691 A1. Examples of preferred carbazole derivatives are, 1 ,3-N,N- dicarbazolebenzene (= 9,9’-(1 ,3-phenylene)bis-9H-carbazole) (mCP), 9,9’- (2,2’-dimethyl[1 , 1 ’-biphenyl]-4,4’-diyl)bis-9H-carbazole (CDBP), 1 ,3- bis(N,N’-dicarbazole)benzene (= 1 ,3-bis(carbazol-9-yl)benzene), PVK (polyvinylcarbazole), 3,5-di(9H-carbazol-9-yl)biphenyl and compounds of the Formulae 40 to 44. Preferred Si tetraaryl compounds are, for example, (US 2004/0209115, US 2004/0209116, US 2007/0087219 A1 , US 2007/0087219 A1 ) the compounds of the Formulae 45 to 50.

Formula 47 Formula 48 Formula 49 Formula 50

A particularly preferred matrix for phosphorescent dopants is the compound of Formula 51 (EP 652273 B1 )

Formula 51

Further particularly preferred matrix materials for phosphorescent dopants are selected from compounds of the general Formula 52 (EP 1923448 B1 ).

[M(L)₂]_n Formula 52 wherein M, L, and n are defined as in the reference. Preferably M is Zn, and L is quinolinate q, and n is 2, 3 or 4. Very particularly preferred are [Znq₂]2, [Znq₂]3, and [Znq₂]₄.

Preference is given to co-hosts selected from metal oxinoid complexes whereby lithium quinolate (Liq) or Alq₃ are particularly preferred. The emitter compound is required to have a smaller band gap as compared to the host compound. In general, smaller band gaps can be achieved by extending the tt-electron system of conjugated molecular systems. Emitter compounds tend, therefore, to have more extended conjugated tt-electron systems than host molecules. Many examples have been published, e.g. styrylamine derivatives as disclosed in JP 2913116B and WO 2001/021729 A1, and indenofluorene derivatives as disclosed in WO 2008/006449 and WO 2007/140847.

Blue fluorescent emitters are preferably polyaromatic compounds, such as, for example, 9, 10-di(2-naphthylanthracene) and other anthracene derivatives, derivatives of tetracene, xanthene, perylene, such as, for example, 2,5,8, 11 -tetra-t-butylperylene, phenylene, for example 4, 4’-(bis(9- ethyl-3-carbazovinylene)-1 ,1 ’-biphenyl, fluorene, arylpyrenes (US 2006/0222886), arylenevinylenes (US 5121029, US 5130603), derivatives of rubrene, coumarine, rhodamine, quinacridone, such as, for example, N,N’-dimethylquinacridone (DMQA), dicyanomethylenepyrane, such as, for example, 4 (dicyanoethylene)-6-(4-dimethylaminostyryl-2- methyl)-4H-pyrane (DCM), thiopyrans, polymethine, pyrylium and thiapyrylium salts, periflanthene, indenoperylene, bis(azinyl)imine-boron compounds (US 2007/0092753 A1 ), bis(azinyl)methene compounds and carbostyryl compounds.

Further preferred blue fluorescent emitters are described in C.H. Chen et al. : "Recent developments in organic electroluminescent materials" Macromol. Symp. 125, (1997), 1-48 and “Recent progress of molecular organic electroluminescent materials and devices” Mat. Sci. and Eng. R, 39 (2002), 143-222.

Preferred fluorescent dopants according to the present invention are selected from the class of the monostyrylamines, the distyrylamines, the tristyrylamines, the tetrastyrylamines, the styrylphosphines, the styryl ethers and the arylamines.

A monostyrylamine is taken to mean a compound which contains one substituted or unsubstituted styryl group and at least one, preferably aromatic, amine. A distyrylamine is taken to mean a compound which contains two substituted or unsubstituted styryl groups and at least one, preferably aromatic, amine. A tristyrylamine is taken to mean a compound which contains three substituted or unsubstituted styryl groups and at least one, preferably aromatic, amine. A tetrastyrylamine is taken to mean a compound which contains four substituted or unsubstituted styryl groups and at least one, preferably aromatic, amine. The styryl groups are particularly preferably stilbenes, which may also be further substituted. The corresponding phosphines and ethers are defined analogously to the amines. For the purposes of this invention, an arylamine or an aromatic amine is taken to mean a compound which contains three substituted or unsubstituted aromatic or heteroaromatic ring systems bonded directly to the nitrogen. At least one of these aromatic or heteroaromatic ring systems is preferably a condensed ring system, preferably having at least 14 aromatic ring atoms. Preferred examples thereof are aromatic anthracene- amines, aromatic anthracene-diamines, aromatic pyrene-amines, aromatic pyrene-diamines, aromatic chrysene-amines and aromatic chrysene- diamines. An aromatic anthracene-amine is taken to mean a compound in which one diarylamino group is bonded directly to an anthracene group, preferably in the 9 position. An aromatic anthracene-diamine is taken to mean a compound in which two diarylamino groups are bonded directly to an anthracene group, preferably in the 9,10-position. Aromatic pyrene- amines, pyrene-diamines, chrysene-amines and chrysene-diamines are defined analogously thereto, where the diarylamino groups on the pyrene are preferably bonded in the 1 position or in the 1 ,6-position.

Further preferred fluorescent dopants are selected from indenofluorene- amines and indenofluorene-diamines, for example in accordance with WO 2006/122630, benzoindenofluorene-amines and benzoindeno- fluorene-diamines, for example in accordance with WO 2008/006449, and dibenzoindenofluorene-amines and dibenzoindenofluorene-diamines, for example in accordance with WO 2007/140847.

Examples of dopants from the class of the styrylamines are substituted or unsubstituted tristilbene-amines or the dopants described in WO 2006/000388, WO 2006/058737, WO 2006/000389, WO 2007/065549 and WO 2007/115610. Distyrylbenzene and distyrylbiphenyl derivatives are described in US 5121029. Further styrylamines are found in US 2007/0122656 A1. Particularly preferred styrylamine dopants and triarylamine dopants are compounds of the Formulae 53 to 58 and as disclosed in US 7250532 B2, DE 102005058557 A1, CN 1583691 A, JP 08053397 A, US 6251531 B1, and US 2006/210830 A.

Formula 57 Formula 58

Further preferred fluorescent dopants are selected from the group of triarylamines as disclosed in EP 1957606 A1 and US 2008/0113101 A1.

Further preferred fluorescent dopants are selected from derivatives of naphthalene, anthracene, tetracene, fluorene, periflanthene, indenoperylene, phenanthrene, perylene (US 2007/0252517 A1), pyrene, chrysene, decacyclene, coronene, tetraphenylcyclopentadiene, pentaphenylcyclopentadiene, fluorene, spirofluorene, rubrene, coumarine (US 4769292, US 6020078, US 2007/0252517 A1), pyran, oxazone, benz- oxazole, benzothiazole, benzimidazole, pyrazine, cinnamic acid esters, diketopyrrolopyrrole, acridone and quinacridone (US 2007/0252517 A1). Of the anthracene compounds, particular preference is given to 9,10- substituted anthracenes, such as, for example, 9,10-diphenylanthracene and 9, 10-bis(phenylethynyl)anthracene 1 ,4-Bis(9’-ethynylanthracenyl)- benzene is also a preferred dopant. Examples of phosphorescent emitters are revealed by the applications

WO 00/70655, WO 01/41512, WO 02/02714, WO 02/15645, EP 1191613, EP 1191612, EP 1191614 and WO 2005/033244. In general, all phosphorescent complexes as used in accordance with the prior art for phosphorescent OLEDs and as are known to the person skilled in the art in the area of organic electroluminescence are suitable, and the person skilled in the art will be able to use further phosphorescent complexes without inventive step.

The phosphorescent emitter may be a metal complex, preferably with the formula M(L)_Z, wherein M is a metal atom, L is in each occurrence independently of one another an organic ligand that is bonded to or coordinated with M via one, two or more positions, and z is an integer > 1 , preferably 1 , 2, 3, 4, 5 or 6, and wherein, optionally, these groups are linked to a polymer via one or more, preferably one, two or three positions, preferably via the ligands L.

M is in particular a metal atom selected from transition metals, preferably selected from transition metals of group VIII, or lanthanoides, or actinides, particularly preferably selected from Rh, Os, Ir, Pt, Pd, Au, Sm, Eu, Gd, Tb, Dy, Re, Cu, Zn, W, Mo, Pd, Ag, or Ru, and very particularly preferably selected from Os, Ir, Ru, Rh, Re, Pd, or Pt. M may also be Zn.

Preferred ligands are 2 phenylpyridine derivatives, 7,8-benzoquinoline derivatives, 2 (2-thienyl)pyridine derivatives, 2 (l-naphthyl)pyridine derivatives or 2 phenylquinoline derivatives. All these compounds may be substituted, for example by fluoro- or trifluoromethyl substituents for blue. Auxiliary ligands are preferably acetylacetonate or picric acid.

In particular, complexes of Pt or Pd with tetradentate ligands of the Formula 59 as disclosed in US 2007/0087219 A1 , wherein R¹ to R¹⁴ and Z¹ to Z⁵ are as defined in the reference, Pt porphyrin complexes having an enlarged ring system (US 2009/0061681 A1) and Ir complexes are suitable, for example 2, 3, 7, 8, 12,13,17,18-octaethyl-21 H, 23H-porphyrin- Pt(ll), tetraphenyl-Pt(ll)-tetrabenzoporphyrin (US 2009/0061681 A1), cis- bis(2-phenylpyridinato-N,C2’)Pt(ll), cis-bis(2-(2’-thienyl)pyridinato- N,C3’)Pt(ll), cis-bis(2-(2’-thienyl)quinolinato-N,C5’)Pt(ll), (2-(4,6- difluorophenyl)pyridinato-N,C2’)Pt(ll) acetylacetonate, or tris(2- phenylpyridinato-N,C2’)lr(lll) (lr(ppy)3, green), bis(2-phenylpyridinato- N, C2)lr(l 11) acetylacetonate (lr(ppy)2 acetylacetonate, green, US 2001/0053462 A1 , Baldo, Thompson et al. Nature 403, (2000), 750- 753), bis(1 -phenylisoquinolinato-N,C2’)(2-phenylpyridinato- N,C2’)iridium(lll), bis(2-phenylpyridinato-N,C2’)(1-phenylisoquinolinato- N,C2’)iridium(lll), bis(2-(2’-benzothienyl)pyridinato-N,C3’)iridium(lll) acetylacetonate, bis(2-(4’,6’-difluorophenyl)pyridinato-N,C2’)iridium(lll) piccolinate (Firpic, blue), bis(2-(4’,6’-difluorophenyl)pyridinato-N,C2’)lr(lll) tetrakis(1 -pyrazolyl)borate, tris(2-(biphenyl-3-yl)-4-tert-butylpyridine)- iridium(lll), (ppz)₂lr(5phdpym) (US 2009/0061681 A1), (45ooppz)₂lr(5phdpym) (US 2009/0061681 A1), derivatives of 2 phenylpyridine-lr complexes, such as, for example, iridium(lll) bis(2- phenylquinolyl-N,C2’)acetylacetonate (PQIr), tris(2-phenylisoquinolinato- N,C)lr(lll) (red), bis(2-(2’-benzo[4,5-a]thienyl)pyridinato-N,C3)lr acetylacetonate ([Btp2lr(acac)], red, Adachi et al. Appl. Phys. Lett. 78 (2001), 1622-1624).

Formula 59

Also suitable are complexes of trivalent lanthanides, such as, for example, Tb³⁺ and Eu³⁺ (J. Kido et al. Appl. Phys. Lett. 65 (1994), 2124, Kido et al. Chem. Lett. 657, 1990, US 2007/0252517 A1), or phosphorescent complexes of Pt(ll), lr(l), Rh(l) with maleonitrile dithiolate (Johnson et al., JACS 105, 1983, 1795), Re(l) tricarbonyl diimine complexes (Wrighton, JACS 96, 1974, 998 inter alia), Os(ll) complexes with cyano ligands and bipyridyl or phenanthroline ligands (Ma et al., Synth. Metals 94, 1998, 245) or Alq3 without a host. Further phosphorescent emitters with tridentate ligands are described in US 6824895 and US 7029766. Red-emitting phosphorescent complexes are mentioned in US 6835469 and US 6830828. A particularly preferred phosphorescent dopant is a compound of the

Formula 60 and further compounds as disclosed, e.g., in US 2001/0053462 A1.

A particularly preferred phosphorescent dopant is a compound of the Formula 61 and further compounds as disclosed, e.g., in WO 2007/095118 A1

Further derivatives are described in US 7378162 B2, US 6835469 B2, and JP 2003/253145 A.

Further to metal complex mentioned elsewhere herein, a suitable metal complex according to the present invention can be selected from transition metals, rare earth elements, lanthanides and actinides is also subject of this invention. Preferably the metal is selected from Ir, Ru, Os, Eu, Au, Pt, Cu, Zn, Mo, W, Rh, Pd, or Ag. Further to dyes mentioned elsewhere herein, dyes according to the present invention can be selected from perylenes, ruthenium dyes, phthalocyanines, azo dyes, perylene-diimides, porphyrines, squaraines, isomers and derivatives thereof.

Preferably the dye is selected from perylenes, ruthenium dyes, phthalocyanines, azo dyes, perylene-diimides, porphyrines, and squaraines. Also preferred are dyes selected from ruthenium complexes as disclosed by Yu Bai et. al., in Nature Materials, Vol. 7, 626 (2008) and by B. O’Regan et. al., in Nature 353, 737 (1991), and Cu based complexes as disclosed by Bessho et al, in Chem. Commun. 3717 (2008).

Further dyes are selected from acridines, anthraquinones, arylmethanes, diarylmethanes, triarylmethanes, azo-based dyes, cyanines, diazonium- based dyes, nitro-based dyes, nitroso-based dyes, quinone-imines, azin- based dyes, eurhodines, safranines, indulines, indamins, indophenoles, oxazines, oxazones, thiazines, thiazoles, xanthenes, fluorenes, pyronines, fluorones, and rhodamines.

In addition to dyes according to the present invention, charge generation materials can also have the same function as a dye. They are, for example, used for electrophotographic devices. Thus charge generation materials as summarized by Paul M.Borsenberger; and David S. Weiss in Organic Photoreceptors for Xerography; Marcel Dekker, Inc., 1998, Chapter 6, and by K. Y. Law, Chem. Rev. Vol. 93, 449-486 (1993) are herein also considered as suitable dyes.

Further suitable dyes are selected from organic compounds containing fused ring system, for example anthracene, naphthalene, pentacene and tetracene derivatives. Formulations according to the present invention may also comprise organic functional material which is selected from polymers, oligomers, dendrimers, and blends. The functional polymer is characterized in that different functions may be incorporated into one large molecule or a blend of large molecules. The functions are, inter alia, the ones of a hole injection material, hole transport material, electron blocking material, emissive material, hole blocking material, electron injection material, electron transport material, and dye. The functions which are incorporated into a polymer can be categorized into different groups. By choosing the desired functional groups and the ratio between them, the polymer can be tuned to have the desired function(s). The difference between polymers, oligomers and dendrimers is due to the size, size distribution, and branching of the molecular entities as defined above. Different structures are, inter alia, those as disclosed and extensively listed in WO 2002/077060 A1 and in DE 10337346 A1. The structural units may originate, for example, from the following groups:

Group 1 : units which increase the hole-injection and/or transport properties of the polymers; it corresponds to the HIMs or HTMs as described above.

Group 2: units which increase the electron-injection and/or transport properties of the polymers; it corresponds to the EIMs or ETMs as described above.

Group 3: units which have combinations of individual units from group 1 and group 2.

Group 4: units which modify the emission characteristics to such an extent that electrophosphorescence may be obtained instead of electrofluorescence; typically, it corresponds to the phosphorescent emitter, or more preferably emissive metal complexes as described above.

Group 5: units which improve the transition from the so called singlet state to higher spin states, e.g. to a triplet state.

Group 6: units which influence the morphology and/or emission colour of the resultant polymers. Group 7: units which are typically used as backbone and which may have electron transport function, hole transport function or both.

Group 8: units which have strong absorption in at least one wavelength from UV to infrared. It corresponds to the dye materials as described above. Preferably, the said organic functional material is a hole transport or injection polymer comprising units of group 1 , which are preferably selected from units comprising the low molecular weight HTMs or HIMs as described above.

Further preferred units of group 1 are, for example, triarylamine, benzidine, tetraaryl-para-phenylenediamine, carbazole, azulene, thiophene, pyrrole and furan derivatives and further 0, S or N containing heterocycles with a high HOMO. These arylamines and heterocycles preferably result in an HOMO in the polymer of greater than 5.8 eV (against vacuum level), particularly preferably greater than 5.5 eV.

A preferred polymeric HTM or HIM is a polymer comprising at least one repeating unit of the following Formula 62.

Formula 62 wherein

Ar¹ which may be the same or different, denote, independently if in different repeat units, a single bond or an optionally substituted mononuclear or polynuclear aryl group,

Ar² which may be the same or different, denote, independently if in different repeat units, an optionally substituted mononuclear or polynuclear aryl group,

Ar³ which may be the same or different, denote, independently if in different repeat units, an optionally substituted mononuclear or polynuclear aryl group, and m is 1 , 2 or 3. Particularly preferred units of Formula 62 are selected from Formulae 63 to 65:

Formula 65 wherein

R which may be the same or different in each occurrence, is selected from

H, substituted or unsubstituted aromatic or heteroaromatic group, alkyl, cycloalkyl, alkoxy, aralkyl, aryloxy, arylthio, alkoxycarbonyl, silyl, carboxy group, a halogen atom, cyano group, nitro group or hydroxy group, r is 0, 1 , 2, 3 or 4, and s is O, 1 , 2, 3, 4 or 5.

A further preferred polymeric FITM or HIM is a polymer comprising at least one repeating unit of the following Formula 66. - (T¹ )_{c -} (Ar⁴ )_{d -} (T² )_{e -} (Ar⁵ )_{f - Form}ula 66 wherein

T¹ and T² are independently of each other selected from thiophene, selenophene, thieno[2,3b]thiophene, thieno[3,2b]thiophene, dithienothiophene, pyrrole, aniline, all of which are optionally substituted with R⁵,

R⁵ is in each occurrence independently of each other selected from halogen, -CN, -NC, -NCO, -NCS, -OCN, SCN, C(=0)NR°R°°, -C(=0)X, - C(=0)R°, -NH₂, -NR°R⁰⁰, SH, SR°, -SOSH, -S0₂R°, -OH, -NO₂, -CF₃, -SF₅, optionally substituted silyl, or carbyl or hydrocarbyl with 1 to 40 C atoms that is optionally substituted and optionally contains one or more hetero atoms,

Ar⁴ and Ar⁵ are independently of each other mononuclear or polynuclear aryl or heteroaryl, which is optionally substituted and optionally fused to the 2,3-positions of one or both of the adjacent thiophene or selenophene groups, c and e are independently of each other 0, 1 , 2, 3 or 4, with 1 < c + e < 6, d and f are independently of each other 0, 1 , 2, 3 or 4.

Examples of polymeric HTMs are as disclosed in WO 2007/131582 A1 and WO 2008/009343 A1.

Preferably, the said organic functional material is an electron transport or injection polymer comprising units of group 2, which are preferably selected from groups comprising the low molecular weight ETMs or EIMs as described above.

Further preferred units of group 2, which have electron-injection or electron-transport properties, are, for example, pyridine, pyrimidine, pyridazine, pyrazine, oxadiazole, quinoline, quinoxaline and phenazine derivatives, but also triarylboranes and further 0, S or N containing heterocycles having a low LUMO. These units in the polymer preferably result in an LUMO of less than 2.7 eV (against vacuum level), particularly preferably less than 2.8 eV.

Preferably, the said organic functional material is a polymer comprising units of group 3, in which structures which increase the hole mobility and the electron mobility (i.e. units of group 1 and 2) are bonded directly to one another. Some of these units may serve as emitters and shift the emission colour into the green, yellow or red. Their use is thus suitable, for example, for the production of other emission colours or a broad-band emission from originally blue-emitting polymers. Preferably, the said organic functional material is a polymer comprising units of group 4, which is preferably selected from the groups comprising phosphorescent emitter, particularly emissive metal complexes as described above. Particular preference is given here to corresponding structural units which contain elements from groups 8 to 10 (Ru, Os, Rh, Ir, Pd, Pt).

Preferably, the said organic functional material is a polymeric triple matrix comprising units of group 5, which can improve the transition from the singlet state to the triplet state and which, employed in support of the structural elements of group 4, improve the phosphorescence properties of these structural elements. Suitable for this purpose are, in particular, carbazole and bridged carbazole dimer units, as described in DE 10304819 A1 and DE 10328627 A1. Also suitable for this purpose are ketones, phosphine oxides, sulfoxides, sulfones, silane derivatives and similar compounds, as described in DE 10349033 A1. Further preferred structure units can be selected from groups comprising the low molecular weight phosphorescent matrices as described above.

Preferably, the said organic functional material is a polymer comprising units of group 6, which influence the morphology and/or emission colour of the polymers, are, besides those mentioned above, those which have at least one further aromatic or another conjugated structure which do not fall under the above-mentioned groups, i.e. which have only little effect on the charge-carrier mobilities, which are not organometallic complexes or which have no influence on the singlet-triplet transition. Structural elements of this type may influence the morphology and/or emission colour of the resultant polymers. Depending on the unit, they can therefore also be employed as emitters. Preference is given here, in the case of fluorescent OLEDs, to aromatic structures having 6 to 40 C atoms or also tolan, stilbene or bisstyrylarylene derivatives, each of which may be substituted by one or more radicals R¹. Particular preference is given here to the incorporation of

1.4-phenylene, 1 ,4-naphthylene, 1,4- or 9,10-anthrylene, 1,6-, 2,7- or 4,9- pyrenylene, 3,9- or 3,10-perylenylene, 4,4'-biphenylylene, 4,4"- terphenylylene, 4,4' bi 1,1'-naphthylylene, 4,4‘-tolanylene, 4,4'-stilbenylene or 4,4"-bisstyrylarylene derivatives.

Preferably, the said organic functional material is a polymer comprising units of group 7 which contain aromatic structures having 6 to 40 C atoms which are typically used as polymer backbone. These are, for example,

4.5-dihydropyrene derivatives, 4,5,9, 10-tetrahydropyrene derivatives, fluorene derivatives as disclosed for example in US 5962631 ,

WO 2006/052457 A2 and WO 2006/118345A1 , 9,9‘-spirobifluorene derivatives as disclosed for example in WO 2003/020790 A1 , 9,10- phenanthrene derivatives as disclosed, for example, in WO 2005/104264 A1 , 9,10-dihydrophenanthrene derivatives as disclosed for example in WO 2005/014689 A2, 5,7-dihydrodibenzooxepine derivatives and cis- and trans-indenofluorene derivatives as disclosed for example in WO 2004041901 A1, WO 2004113412 A2 and, binaphthylene derivatives as disclosed for example in WO 2006/063852 A1 , and further units as disclosed for example in WO 2005/056633 A1 , EP 1344788 A1 and WO 2007/043495 A1 , WO 2005/033174 A1 , WO 2003/099901 A1 and DE 102006003710.

Further preferred structural elements of group 7 are selected from fluorene derivatives, as disclosed for example in US 5,962,631 , WO 2006/052457 A2 and WO 2006/118345 A1 , spiro-bifluorene derivatives as disclosed for example in WO 2003/020790 A1 , benzofluorene, dibenzofluorene, benzothiophene, dibenzofluorene and their derivatives as disclosed for example in WO 2005/056633 A1 , EP 1344788 A1 and WO 2007/043495 A1. Very preferred structural elements of group 7 are those of Formula 67:

Formula 67 wherein

A, B and B' are independently of each other, and in case of multiple occurrence independently of one another, a divalent group, preferably selected from -CR¹R²-, -NR¹-, -PR¹-, -0-, -S-, -SO-, -SO2-, -CO-, -CS-, -CSe-, -P(=0)R¹-, -P(=S)R¹- and -SiR¹R²-,

R¹ and R² are independently of each other identical or different groups selected from H, halogen, -CN, -NC, -NCO, -NCS, -OCN, -SON, -C(=0)NR°R⁰⁰, -C(=0)X, -C(=0)R°, -NH₂, -NR°R⁰⁰, -SH, -SR°, -SO3H, -SO₂R⁰, -OH, -NO₂, -CF3, -SF5, optionally substituted silyl, or carbyl or hydrocarbyl with 1 to 40 C atoms that is optionally substituted and optionally comprises one or more hetero atoms, and optionally the groups R¹ and R² form a spiro group with the fluorene moiety to which they are attached,

X is halogen,

R° and R⁰⁰ are independently of each other H or an optionally substituted carbyl or hydrocarbyl group optionally comprising one or more hetero atoms, each g is independently 0 or 1 and each corresponding h in the same subunit is the other of 0 or 1 , m is an integer > 1 ,

Ar¹ and Ar² are independently of each other mono- or polynuclear aryl or heteroraryl that is optionally substituted and optionally fused to the 7,8- positions or 8,9-positions of the indenofluorene group, and a and b are independently of each other 0 or 1.

If the groups R¹ and R² form a spiro group with the fluorene group to which they are attached, it is preferably spirobifluorene. The groups of Formula 67 are preferably selected from Formulae 68 to 72:

Formula 70 wherein R¹ is as defined in Formula 67, r is 0, 1 , 2, 3 or 4, and R has one of the meanings of R¹, and

R is preferably F, Cl, Br, I, -CN, -N0₂ , -NCO, -NCS, -OCN, -SCN, -C(=0)NR°R⁰⁰, -C(=0)X°, -C(=0)R°, -NR°R⁰⁰, optionally substituted silyl, aryl or heteroaryl with 4 to 40, preferably 6 to 20 C atoms, or straight chain, branched or cyclic alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonlyoxy or alkoxycarbonyloxy with 1 to 20, preferably 1 to 12 C atoms, wherein one or more FI atoms are optionally replaced by F or Cl, and wherein R°, R⁰⁰ and X° are as defined above.

Particularly preferred groups of Formula 67 are selected from Formulae 73 to 76: wherein

L is H, halogen or optionally fluorinated, linear or branched alkyl or alkoxy with 1 to 12 C atoms, and is preferably H, F, methyl, i-propyl, t-butyl, n- pentoxy, or trifluoromethyl, and

L' is optionally fluorinated, linear or branched alkyl or alkoxy with 1 to 12 C atoms, and is preferably n-octyl or n-octyloxy.

Preferably, the said organic functional material is a polymer comprising units of group 8, which can be selected from the groups comprising the dye materials as described above. The conjugated polymers suitable for organic solar cells, as summarized for example by F.C. Krebs, in Solar Energy Materials and Solar Cells, Vol. 91, 953 (2007), can also be used as the said further organic functional material in the present invention.

Preference is given to polymers suitable for use in the present invention which simultaneously comprise one or more units selected from groups 1 to 8. It may likewise be preferred for more than one structural unit from a group to be present simultaneously.

Preference is given to polymers suitable for use in the present invention which, besides structural units of an emitter, also comprise at least one structural unit of the above-mentioned groups. At least two structural units are particularly preferably from different classes of those mentioned above.

The proportion of the different classes of groups, if present in the polymer, is preferably in each case at least 5 mol%, particularly preferably in each case at least 10 mol%. In particular, one of these structural units is selected from the group of hole-conducting units and the other group is an emitting unit, where these two functions (hole conduction and emission) may also be taken on by the same unit.

However, a smaller proportion of the emitting units, in particular green- and red-emitting units, may also be preferred, for example for the synthesis of white-emitting copolymers. The way in which white-emitting copolymers can be synthesised is described in detail in DE 10343606 A1.

In order to ensure adequate solubility, it is preferred for on average at least 2 non-aromatic C atoms to be present in the substituents per repeating unit. Preference is given here to at least 4 and particularly preferably at least 8 C atoms. In addition, individual C atoms of these may be replaced by O or S. However, it is entirely possible for this to mean that a certain proportion of repeating units does not carry any further non-aromatic substituents.

In order to avoid impairing the morphology of the film, it is preferred to have no long-chain substituents having more than 12 C atoms in a linear chain, particularly preferably none having more than 8 C atoms and in particular none having more than 6 C atoms.

The polymer used as organic functional material in the present invention may be a statistical or random copolymer, an alternating or regioregular copolymer, a block copolymers or a combination thereof.

In another preferred embodiment, the said polymer is a side-chain non- conjugated polymer, which is especially important for phosphorescent OLEDs based on polymer. In general, such a phosphorescent polymer is obtained by means of radical copolymerization of vinyl compounds, and comprises at least one phosphorescent emitter and at least one charge transport unit on side chain, as disclosed in US 7250226 B2. Further examples for such phosphorescent polymers are disclosed for example in JP 2007/211243 A2, JP 2007/197574 A2, US 7250226 B2, and JP 2007/059939 A.

In a further preferred embodiment, the said polymer is a main-chain non- conjugated polymer, where the backbone units are connected by spacer on main-chain. Like side-chain non-conjugated polymer, main-chain non- conjugated polymers give also a high triplet level. An example for triplet OLEDs based on main-chain non-conjugated polymers is disclosed in DE 102009023154. In a further embodiment, the said polymer can also be a non-conjugated polymer for fluorescent OLEDs. Preferred singlet non-conjugated polymers are, for example, side-chain polymers with antracenenes, benzanthracenes and their derivatives in the side-chain, as disclosed in JP 2005/108556,

JP 2005/285661, and JP 2003/338375.

The said polymers can also act as ETM or HTM, preferably the polymer is a non-conjugated polymer.

Devices according to the present invention may also comprise additional layer which were not deposited by using a formulation, i.e. a emulsion or dispersion, according to the present invention. The additional layer may be deposited by a technique from solution or by vapour deposition. Hereby the specific method employed depends on the characteristics of the material used and a person skilled in the art has no problem to select the appropriate technique. The material which is deposited can be any material used in the field of electronic and opto-electronic multilayer structures. In particular the material may be any material described herein. Furthermore, the materials may be selected from organic and inorganic functional materials as outlined below. Inorganic compounds, such as p type Si and p type SiC, and inorganic oxides, e.g., vanadium oxide (VO_x), molybdenum oxide (MoO_x) or nickel oxide (NiO_x) can also be used as HIM.

Electron injection layers (EILs) are often constructed from an insulator and semiconductor.

Preferred alcali metal chalcogenides for EILs are LhO, LiO, Na2S, Na2Se, NaO, K2O, and CS2O. Preferred alkaline-earth metal chalcogenides for EILs are CaO, BaO, SrO, BeO, BaS, and CaSe.

Preferred halides of alkali metals for EILs are LiF, NaF, KF, CsF, LiCI, KCI, and NaCI.

Preferred halides of alkaline-earth metals for EILs are CaF2, BaF2, SrF2, MgF2, and BeF2.

It is likewise possible to employ alkali metal complexes, alkaline-earth metal complexes, rare-earth metals (Sc, Y, Ce, Th, Yb), rare-earth metal complexes, rare-earth metal compounds (preferably YbF3, SCF3, TbFs) or the like.

The structure of EILs is described, for example, in US 5608287, US 5776622, US 5776623, US 6137223, US 6140763, US 6914269. An electron-transport layer may consist of an intrinsic material or comprise a dopant. Alq3 (EP 278757 B1) and Liq (EP 0569827 A2) are examples of intrinsic layers. 4,7-diphenyl-1 ,10-phenanthroline (Bphen):Li 1:1 (US 2003/02309890) and rubrene/LiF are examples of doped layers.

In addition to the materials mentioned above, an organic electroluminescent device according to the present invention may comprise at least one anode, at least one cathode and one or more substrates. Preferred materials for the anode are metal oxides selected from, but not limited to, indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO), ZnO, InO, aluminium-zinc-oxide (AIZnO), and other metal oxides such as Al- and In-zinc oxide doped with zinc oxide, magnesium-indium-oxide, and nickel-tungsten-oxide. Metal nitrides such as galliumnitrides and metal selenides such as zinc-selenide and metal-sulfides such as zinc-sulfide can also be used. Further materials that can be used for anodes are electrically conducting polymers, e.g. polythiophenes and polypyrroles.

The anode can be transparent, opaque, or reflective. The anode can also adopt an intermediate state, e.g. both being partially reflective and partially transparent.

If the anode is not or only partially transparent further conducting materials can be used. Preferred materials for non transparent or partially transparent anodes are selected from, but not limited to, Au, Ir, Mo, Pd, Pt, Cu, Ag, Sn, C, Al, V, Fe, Co, Ni, W, and mixtures thereof. The conducting materials can also be mixed with further conducting materials as described above, e.g. In-Cu. The anode is preferably transparent and a particularly preferred material for the anode is ITO. In the case of a bottom-emitting device glass or plastic is preferably coated with ITO. In the case of a top-emitting device the anode comprises preferably a reflecting material. Further materials can be used for anodes, which are known to the person skilled in the art. A flexible and transparent combination of substrate and anode is described in US 5844363 B2 and US 6602540 B2, for instance.

The cathode can be transparent, opaque, or reflective. The cathode is selected from a metal or an alloy with a low work function. Preferably metals, alloys, or conducting compounds or materials with a work function of less than 4.0 eV are used. Particularly preferred cathodes are selected from, but not limited to, Ba, Ca, Sr, Yb, Ga, Cd, Si, Ta, Sb, Zn, Mg, Al, In,

Li, Na, Cs, Ag, mixtures of two or more elements such as alloys comprising Mg/AI or Al/Li or Al/Sc/Li or Mg/Ag or metal oxides such as ITO or IZO.

Further preferred materials for cathodes, used to form a thin dielectric layer, are selected from a metal which is mixed with LiF, LhO, BaF2, MgO, or NaF. A typical combination is LiF/AI.

A Mg/AI cathode with ITO layer on top is described in US 5703436,

US 5707745, US 6548956 B2, US 6576134 B2. A Mg/Ag alloy is described in US 4885221. The substrate may be rigid or flexible. It may be transparent, translucent, opaque or reflective. The materials used can be glass, plastic, ceramic or metal foils, where plastic and metal foils are preferably used for flexible substrates. However, semiconductor materials, such as, for example, silicone wafers or printed circuit board (PCB) materials, can also be employed in order to simplify the generation of conductor tracks. Other substrates can also be employed.

The glass used can be, for example, soda-lime glass, Ba- or Sr-containing glass, lead glass, aluminium silicate glass, borosilicate glass, Ba borosilicate glass or quartz.

Plastic plates can consist, for example, of polycarbonate resin, acrylic resin, vinyl chloride resin, polyethylene terephthalate resin, polyimide resin, polyester resin, epoxy resin, phenolic resin, silicone resin, fluorine resin, polyether sulfide resin or polysulfone resin. For transparent films, use is made, for example, of polyethylene, ethylene- vinyl acetate copolymers, ethylene-vinyl alcohol copolymers, poly propylene, polystyrene, polymethyl methacrylate, PVC, polyvinyl alcohol, polyvinylbutyral, nylon, polyether ether ketone, polysulfone, polyether sulfone, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymers, polyvinyl fluoride, tetrafluoroethylene-ethylene copolymers, tetrafluoroethylene- hexafluoropropylene copolymers, polychlorotrifluoroethylene, polyvinylidene fluoride, polyester, polycarbonate, polyurethanes, polyimide or polyether imide.

The substrate is provided with a hydrophobic layer. The substrates are preferably transparent.

Other materials than those mentioned here can also be used. Suitable materials are known to the person skilled in the art.

In a preferred embodiment of the present invention the formulation is characterized in that the discontinuous phase comprises at least one emitter material and at least one host material, more preferably it comprises two emitter materials and one host material and most preferably it comprises one emitter and one host. Both host materials and emitter materials are selected from the corresponding materials as described in the present application. If at least two emitter materials are present in the discontinuous phase it is preferable that the absorption spectrum of one emitter overlaps with the photoluminescence (PL) spectrum of another emitter in order to take advantage the Forster energy transfer. PL spectra of the emitter can be measured according to standard techniques well known to a person skilled in the art.

In a preferred embodiment the formulation according to the invention is characterized in that the at least one emitter material is selected from fluorescent and phosphorescent emitter materials and the host material is selected from anthracenes, benzanthracenes, indenofluorenes, fluorenes, spirobifluorenes, phenanthrenes, diehydrophenanthrenes, thiophenes, triazines, imidazole, ketones, carbazoles, triarylamines, and derivatives thereof.

Preference is given to fluorescent emitter and fluorescent host materials. Another subject of the present invention is, therefore, a formulation, characterized in that it comprises in the discontinuous phase at least one fluorescent emitter and at least one host material. Preferably the formulation comprises 3 fluorescent emitter materials and one host material, more preferably it comprises 2 fluorescent emitter and one host material, and most preferably it comprises one fluorescent emitter and one host material.

The formulation of the present invention may also comprise one or more additional fluorescent hosts, so called co-hosts. In principle any of the fluorescent emitter and fluorescent host known to one skilled in the art can be employed in formulations of the present invention. Preferably, the fluorescent emitter and host materials are selected from the fluorescent emitter and fluorescent host materials as described in the present application.

In a preferred embodiment of the present invention the fluorescent host material is selected from anthracenes, benzanthracenes, indenofluorenes, fluorenes, spirobifluorenes, phenanthrenes, dihydrophenanthrenes, thiophenes, triazines, imidazole and derivatives thereof.

Further preference is given to phosphorescent emitter and phosphorescent host materials. Another subject of the present invention is, therefore, an formulation, characterized in that it comprises in the discontinuous phase at least one phosphorescent emitter and at least one host material. Preferably the formulation comprises 3 phosphorescent emitter materials and one host material, more preferably it comprises 2 phosphorescent emitter materials and one host material, and most preferably it comprises one phosphorescent emitter material and one host material. The formulation according to the present invention may also comprise one or more additional hosts, so called co-hosts. In principle any of the phosphorescent emitter and hosts known to one skilled in the art can be employed in formulations of the present invention. Preferably, the phosphorescent emitter and host materials are selected from the phosphorescent emitter and phosphorescent host materials for phosphorescent emission, e.g. from electronically excited triplet or quintet states, as described in the present application.

In a preferred embodiment of the present invention the host for phosphorescent emission is selected from ketones, carbazoles, triaryamines, indenofluorenes, fluorenes, spirobifluorenes, phenanthrenes, dehydrophenanthrenes, thiophenes, triazines, imidazoles and derivatives thereof.

Preferably the said phosphorescent emitter is selected from metal complexes comprising metal selected from the group consisting of transition metals, rare earth, lanthanide and actinide, and preferably selected from the group consisting of Ir, Ru, Os, Eu, Au, Pt, Cu, Zn, Mo, W, Rh, Pd and Ag; and the said host is preferably selected from compounds comprising ketone, carbazole, triaryamine, indenofluorenes, fluorenes, spirobifluorenes, phenanthrenes, dihydrophenanthrenes, phosphine, phosphinoxide, thiophenes, triazines, imidazole and derivatives thereof.

In another preferred embodiment, the said formulation comprises at least two phosphorescent emitters and one host material. Very preferably, the absorption spectrum of the one phosphorescent emitter overlaps with the photoluminescence of the other phosphorescent emitter, therefore Forster energy transfer may be preferably occur between the two phosphorescent emitters. Further preferably, the one phosphorescent emitter emits blue- green light and the second one green or red light.

The present invention further relates to a formulation, characterized in that the discontinuous phase comprises at least one electron transport material. Preferably the formulation according to the present invention comprises 3 ETMs, more preferably 2 ETMs, and most preferably one ETM. In principle any of the ETMs known to one skilled in the art can be employed in the formulations of the present invention. Preferably, the ETMs are selected from the ETMs as described in the present application.

Preferred ETM are selected from imidazoles, pyridines, pyrimidines, pyridazines, pyrazines, oxadiazoles, chinolines, chinoxalines, anthracenes, benzanthracenes, pyrenes, perylenes, benzimidazoles, triazines, ketones, phosphine, phosphinoxides, phenazines, phenanthrolines, triarylboranes and derivatives thereof. The present invention further relates to a formulation, characterized in that the discontinuous phase comprises at least one electron injection material. Preferably the formulation according to the invention comprises 3 EIMs, more preferably 2 EIMs, and most preferably one EIM. In principle any of the EIMs known to one skilled in the art can be employed in the formulations of the present invention. Preferably, the EIMs are selected from the EIMs as described in the present application.

Preferred EIM are selected from imidazoles, pyridines, pyrimidines, pyridazines, pyrazines, oxadiazoles, chinolines, chinoxalines, anthracenes, benzanthracenes, pyrenes, perylenes, benzimidazoles, triazines, ketones, phosphine, phosphinoxides, phenazines, phenanthrolines, triarylboranes and derivatives thereof.

The present invention further relates to a formulation, characterized in that the discontinuous phase comprises at least one hole transport material.

Preferably the formulation according to the present invention comprises 3 HTMs, more preferably 2 HTMs, and most preferably one HTM. In principle any of the HTMs known to one skilled in the art can be employed in the formulations of the present invention. Preferably, the HTMs are selected from the HTMs as described in the present application.

Preferred HTMs are selected from amines, triarylamines, thiophenes, carbazoles, phthalocyanines, porphyrines and derivatives thereof. The present invention further relates to a formulation, characterized in that the discontinuous phase comprises at least one hole injection material. Preferably the formulation according to the present invention comprises 3 HIMs, more preferably 2 HIMs, and most preferably one HIM. In principle any of the HIMs known to one skilled in the art can be employed in formulations of the present invention. Preferably, the HIMs are selected from the HIMs as described in the present application.

Preferred HTMs are selected from amines, triarylamines, thiophenes, carbazoles, phthalocyanines, porphyrines and derivatives thereof. The present invention further relates to a formulation, characterized in that the discontinuous phase comprises at least one metal complex. Preferably the formulation according to the present invention comprises 3 metal complexes, more preferably 2 metal complexes, and most preferably one metal complex. In principle any of the metal complexes known to one skilled in the art can be employed in formulations of the present invention. Preferably, the metal complexes are selected from the metal complexes as described in the present application.

Preferred metal complexes are selected from transition metals, rare earth, lanthanide and actinide. Particularly preferred metal complexes comprise metals selected from Ir, Ru, Os, Eu, Au, Pt, Cu, Zn, Mo, W, Rh, Pd, and Ag.

The present invention further relates to a formulation, characterized in that the discontinuous phase comprises at least one dye. Preferably the formulation according to the present invention comprises 3 dyes, more preferably 2 dyes, and most preferably one dye. In principle any of the dyes known to one skilled in the art can be employed in formulations of the present invention. Preferably, the dyes are selected from the dyes as described in the present application.

Preferred dyes are selected from perylenes, ruthenium dyes, phthalocyanines, azo compounds, perylene diimides, porphyrines, squaraine compounds, and derivatives thereof. In a further preferred embodiment the said formulation comprises at least one dye and optionally an organic functional material, wherein at least one of them is a small molecule organic functional material. The said dye can be selected from the materials as described above. The said organic functional material is preferably selected from an ETM or HTM or host material as described above. A further preferred organic functional material is an electron acceptor, preferably selected from fullerenes, for example C60, carbon nanotubes, graphene and derivatives thereof. Preferably for photovoltaic applications, the said dye and said further organic functional material form a type II energy offset structure, with an energy offset larger than 0.4 eV, preferably larger than 0.5 eV and particularly preferably larger than 0.6 eV.

Further preferred fullerenes suitable for the present invention are selected from the group consisting of carbon allotropes, molecules composed entirely of carbon, in the form of a hollow sphere, ellipsoid, tube, or plane. Spherical fullerenes are also called buckyballs, and cylindrical ones are called carbon nanotubes or buckytubes. Graphene is an example of a planar fullerene sheet.

The present invention further relates to a formulation comprising at least one continuous phase and at least one discontinuous phase, characterized in that the formulation comprises at least one quantum dot. Preferably the formulation comprises one continuous and one discontinuous phase and at least one quantum dot, preferably 1 to 100, more preferably 1 to 50 and most preferably 1 to 10 quantum dots.

Particularly preferably the formulation comprises one continuous and one discontinuous phase and 1 to 5, preferably 1 to 4, more preferably 1 to 3 and most preferably 1 to 2 quantum dots.

Very particularly preferably the formulation comprises one continuous and one discontinuous phase and one quantum dot. The quantum dot(s) can be located in both the discontinuous and/or continuous phase. Preferably the quantum dot(s) is(are) located in the discontinuous phase of the formulation. Another embodiment of the present invention relates to formulations comprising organic functional materials in the discontinuous phase as described above and, in addition to that, at least one quantum dot. The quantum dot(s) can again be located both either in the discontinuous phase and/or in the continuous phase, preferably the quantum dot(s) is(are) located in the discontinuous phase.

In one further preferred embodiment the formulation according to the present invention comprises a small molecule organic fluorescent emitter in the discontinuous phase and at least one, preferably 1 to 3, more preferably 1 to 2, and most preferably 1 quantum dot(s). The quantum dot(s) is preferably located within the discontinuous phase.

In one further preferred embodiment the formulation according to the present invention comprises small molecule organic phosphorescent emitter in the discontinuous phase and at least one, preferably 1 to 3, more preferably 1 to 2, and most preferably 1 quantum dot(s). The quantum dot(s) is preferably located within the discontinuous phase.

Quantum dots represent another class of emissive material. They are also called mono-dispersive nanocrystal as described below. The advantages of quantum dots are: 1) theoretical internal quantum efficiency as high as 100%, compared to 25% of the singlet organic emitter; 2) soluble in common organic solvents; 3) emission wavelength can be easily tuned by the core size; 4) narrow emission spectrum; 5) intrinsic stability in inorganic materials.

The first mono-dispersive nanocrystals including a semiconducting material, also referred to herein as quantum dots or QDs, were based on CdE (E=S, Se, Te) and were produced using the so called TOPO (trioctyl phosphine oxide) method by Bawendi and later modified by Katari et al. A review on synthesis of QDs is given by Murray, Norris and Bawendi, “Synthesis and characterization of nearly monodisperse CdE (E = sulfur, selen, tellurium) semiconductor nanocrystallites”, J. Am. Chem. Soc.

115[19], 8706-8715, 1993. The mostly-reported caps of quantum dots are based on trioctylphosphine oxide (TOPO) or trioctylphosphine (TOP), which are supposed to have electron transporting properties.

Quantum dots can easily be produced and have a narrow emission spectrum in contrast to organic fluorescent or phosphorescent compounds. They can be tailored in terms of size which determines the quantum dot’s emission maximum. High photoluminescent efficiency can also be obtained with quantum dots. Furthermore their emission intensity can be tailored by their concentration employed. Moreover, quantum dots are soluble in many solvents or can easily be made soluble in common organic solvents, allowing versatile processing methods, particularly printing methods such as screen printing, off-set printing, and inkjet printing.

In general, a quantum dot is a semiconductor whose excitons are confined in all three spatial dimensions. As a result, they have properties that are between those of bulk semiconductors and those of discrete molecules. There are several ways to prepare quantum dot structures, for example by chemical methods or by ion implantation, or in nanodevices made by state- of-the-art lithographic techniques.

The quatuim dots of the present application refer to colloidal semiconductor nanocrystals, also known as colloidal quantum dots, or nanodots or nanocrystals, which are produced by chemical methods.

The term quantum dots (QDs) refers to nanocrystals that are substantially mono-disperive in size. A QD has at least one region or characteristic dimension with a dimension of less than about 500 nm, and down to on the order of less than about 1 nm. The term mono-dispersive means the size distribution is within +-10% of the stated value, for example a mono- dispersive nanocrystals of 100 nm in diameter encompasses a range of sizes from 90 nm or larger to 110 nm or smaller. The concentration range of quantum dot(s) in the formulation can be chosen from: preferably between 0.01 and 20 wt%, more preferably between 0.05 and 10 wt%, and most preferably between 0.1 and 5 wt%, referring to the total weight of the formulation.

The first mono-dispersive colloidal quantum dots including a semiconducting material were based on CdE (E = S, Se, Te) and were produced using the so called TOPO (trioctyl phosphine oxide) method by Bawendi and later modified by Katari et al. A review on synthesis of QDs is given by Murray, Norris and Bawendi, “Synthesis and characterization of nearly monodisperse CdE (E = sulfur, selen, tellurium) semiconductor nanocrystallites”, J. Am. Chem. Soc. 115[19], 8706-8715, 1993.

While any method known to the skilled person can be used to create QDs, preferably a solution-phase colloidal method for controlled growth of inorganic QDs is used. The said colloidal methods are disclosed, e.g., by Alivisatos, A. P., "Semiconductor clusters, nanocrystals, and quantum dots," Science 271:933 (1996); X. Peng, M. Schlamp, A. Kadavanich, A. P. Alivisatos, "Epitaxial growth of highly luminescent CdSe/CdS Core/Shell nanocrystals with photostability and electronic accessibility," J. Am. Chem. Soc. 30:7019-7029 (1997); and C. B. Murray, D. J. Norris, M. G. Bawendi, "Synthesis and characterization of nearly monodisperse CdE (E=sulfur, selenium, tellurium) semiconductor nanocrystallites," J. Am. Chem. Soc.

115:8706 (1993). These methods allow low cost processability without the need for clean rooms and expensive manufacturing equipment. In these methods, metal precursors that undergo pyrolysis at high temperature are rapidly injected into a hot solution of organic surfactant molecules. These precursors break apart at high temperatures and react to nucleate nanocrystals. After this initial nucleation phase, a growth phase begins by the addition of monomers to the growing crystal. Thus, crystalline nanoparticles are obtained in solution that have an organic surfactant molecule coating their surface.

In these methods, synthesis occurs as an initial nucleation event that takes place over seconds, followed by crystal growth at elevated temperature for several minutes. Parameters such as the temperature, types of surfactants present, precursor materials, and ratios of surfactants to monomers can be modified so as to change the nature and progress of the reaction. The temperature controls the structural phase of the nucleation event, rate of decomposition of precursors, and rate of growth. The organic surfactant molecules mediate both solubility and control of the nanocrystal shape.

The ratio of surfactants to monomer, surfactants to each other, monomers to each other, and the individual concentrations of monomers strongly influence the kinetics of growth. Suitable semiconducting materials, which can be incoporated into QDs, are selected from elements of Group II- VI, such as CdSe, CdS, CdTe, ZnSe, ZnO, ZnS, ZnTe, HgS, HgSe, HgTe and alloys thereof such as CdZnSe; Group lll-V, such as InAs, InP, GaAs, GaP, InN, GaN, InSb, GaSb, AIP, AIAs, AlSb and alloys such as InAsP, CdSeTe, ZnCdSe, InGaAs; Group IV-VI, such as PbSe, PbTe and PbS and alloys thereof; Group III- VI, such as InSe, InTe, InS, GaSe and alloys such as InGaSe, InSeS; Group IV semiconductors, such as Si and Ge alloys thereof, and combinations thereof in composite structures. Further suitable semiconductor materials include those disclosed in U.S. patent application Ser. No. 10/796,832 and include any type of semiconductor, including group ll-VI, group lll-V, group IV-VI and group IV semiconductors. Suitable semiconductor materials include, but are not limited to, Si, Ge, Sn, Se, Te, B, C (including diamond), P, BN, BP, BAs, AIN, AIP, AIAs, AIS, AlSb, BaS, BaSe, BaTe, CaS, CaSe, CaTe, GaN,

GaP, GaAs, GaSb, InN, InP, InAs, InSb, AIN, AIP, AIAs, AlSb, GaN, GaP, GaAs, GaSb, ZnO, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS, HgSe,

HgTe, BeS, BeSe, BeTe, MgS, MgSe, GeS, GeSe, GeTe, SnS, SnSe, SnTe, PbO, PbS, PbSe, PbTe, CuF, CuCI, CuBr, Cul, Si₃N₄, Ge₃N , Al₂0₃, (Al, Ga, ln)₂ (S, Se, Te)₃, and AI₂CO. Furthermore, further suitable semiconductor materials include combinations of the aforementioned semiconductors and/or combinations with core/shell, core multi-shell layered structures. Yet another embodiment of the present invention is a method for the preparation of a formulation according to the present invention comprising the following steps: a) preparing a first solution comprising at least one first solvent and at least one surfactant; b) preparing a second organic solution comprising at least one organic solvent and at least one organic functional material; c) mixing the first solution obtained in step (a) and the second solution obtained in step (b) in a specific ratio; and d) forming a formulation from the mixture of step (c) by a physical method.

The formulation obtained via this method is an emulsion according to the present invention. Preferably the device used for the physical method of step d) is an ultrasonication device.

A preferred ratio of the first solution to the second solution is in the range from 1:2 to 10:1 in weight, more preferably in the range from 1:1 to 5:1.

Preferably the first solvent is selected from water, alcohol, glycols, ethers, and/or glycol ethers. More preferably the first solvent is a mixture of alcohol, glycol, ether or glycol ether with water. Most preferably the first solvent is a mixture of glycol with water.

The suitable surfactant can be selected from the surfactants as described above. The amount of surfactant(s) is preferably in the range from 0.1 to 20 wt%, more preferably from 0.2 to 10 wt%, and most preferably from 0.5 to 5 wt%, based on the overall weight of the formulation. The suitable second organic solvent can be selected from the organic solvents as described above. Preferably, the weight concentration of the organic functional materials in the second solution is from 0.001 to 20 wt%, more preferably from 0,01 to 10 wt%, and most preferably from 0,1 to 5 wt%.

In a further embodiment of the present invention step d) is conducted by ultrasonic treatment or a high pressure homogenisator or a jet disperser, preferably by ultrasonic treatment.

A formulation according to the present invention can be used for the preparation of a layer and multilayer structure in order to establish a stack of organic functional materials, e.g. for the preparation of electronic or opto-electronic devices such as OLEDs. For further processing it is sometimes advantageous to remove the solvent(s) from one or more discontinuous phases before coating which results in a formulation which is a dispersion comprising the at least one organic functional material.

Therefore, the present invention also relates to a dispersion, characterized in that the dispersion comprises nanoparticles dispersed in a continuous phase formed by removing the solvent of the discontinuous phase of the emulsion according to the present invention. The nanodroplets of the emulsion according to the present invention are, thus, converted into solid nanoparticles which are dispersed in the continuous phase(s) of the formulation. The term dispersion is used herein for a system comprising at least one liquid media (e.g. an aqueous or alcohol-based phase) and an organic phase suspended as solid particle, preferably as nanoparticles.

The present invention also relates to a dispersion comprising nanoparticles dispersed in a continuous phase, characterized in that the nanoparticles comprise at least one organic functional material.

Preferably the nanoparticles comprise 1 to 3, more preferably 1 to 2, and most preferably 1 organic functional material, wherein the at least one organic functional materials is preferably a small molecule organic functional material. The dispersion according to the present invention comprises a continuous phase and at least one organic functional material dispersed in said continuous phase. Said at least one organic functional material is selected from the group of materials as described above.

The dispersion according to the present invention can be prepared from emulsions according to the present invention. Therefore, another subject of the present invention is a method for the preparation of a dispersion by removing the solvent of the discontinuous phase of the emulsion.

Preferably the solvent is removed by evaporation. Particularly preferably evaporation of the solvent is facilitated or at least supported by heating.

The emulsion according to the present invention may comprise one or more surfactants, which may, at least in part, be removed, preferably by diafiltration, after the solvent(s) of the discontinuous phase is removed.

If a surfactant is present it can be removed preferably up to 50%, more preferably up to 75%, and most preferably up to 100% of its original content.

Layer structures are crucial for various organic electronic or opto-electronic devices. The present invention further relates to a method for preparing a layer structure using orthogonal solvents by making use of the formulation, i.e. the emulsion and/or the dispersion, according to the present invention. The formulations according to the present invention can be used in various ways to prepare a layer structure. Preferably the layer structure is a multilayer structure. The preferred ways are described as below:

The first method comprises the following steps:

(a) prepare the first organic layer on a substrate; (b) prepare the second organic layer above the first organic layer by coating a formulation (i.e. emulsion or dispersion) according to the present invention; characterised in that the first organic layer is insoluble or has a limited solubility in the solvent of the continuous phase of the said emulsion or dispersion.

In the said first method, the first layer can either be deposited by thermal evaporation or (preferably) be coated from solution, for example by spin- coating, ink-jet printing, screen printing, slot printing, nozzle printing, etc. In step (b), it is essentially that the first organic layer is insoluble or has only a limited solubility in the solvent of the continuous phase of the said emulsion or dispersion, so that the first layer is still closed after coating the emulsion or the dispersion. Preferably, the maximal solubility of the first layer is less than 0.4 wt% at the working temperature in the solvent of the continuous phase of said emulsion or dispersion. Most preferably the first layer is insoluble in the solvent of the continuous phase of said emulsion or dispersion. The second method comprises the following steps:

(a) prepare the first organic layer on a substrate by coating a formulation (i.e. emulsion or dispersion) according to the present invention; (b) prepare the second organic layer above the first organic layer from a second solution; characterised in that the first organic functional material in the first organic layer is insoluble or has a limited solubility in the solvent of the second solution.

In the said second method, both layers are coated from solution by a coating technique, which can be selected from spin-coating, or printing techniques such as ink-jet printing, screen printing, slot printing, nozzle printing, etc. In step (b), it is essentially that the first organic layer has only a limited solubility in the solvent of the second solution, so that the first layer is still closed after coating the emulsion or the dispersion. Preferably, the maximal solubility of the first layer is less than 0.4 wt% at the working temperature in the solvent of the continuous phase of said emulsion or dispersion. Most preferably the first layer is insoluble in the solvent of the second solution.

The third method comprises the following steps:

(a) prepare the first organic layer on a substrate by coating a formulation (i.e. emulsion or dispersion) according to the present invention;

(b) prepare the second organic layer above the first organic layer from a second dispersion according to the present invention; characterised in that the first organic functional material in the first organic layer is insoluble or has a limited solubility in the solvent of the continuous phase of the second emulsion or dispersion.

In the said third method, both layers are coated from solution by a technique selected from spin-coating, or printing techniques such as ink-jet printing, screen printing, slot printing, nozzle printing, etc. In step (b), it is essentially that the first organic layer has only a limited solubility in the solvent of the continuous phase of the said emulsion or dispersion, so that the first layer is still closed after coating the emulsion or the dispersion. Preferably, the maximal solubility of the first layer is less than 0.4 wt% at the working temperature in the solvent of the continuous phase of said emulsion or dispersion. Most preferably the first layer is insoluble in the solvent of the continuous phase of said emulsion or dispersion.

In a preferred embodiment, the methods as described above for preparing a multilayer structure use a dispersion as coating media.

In a further preferred embodiment of the present invention the method for the preparation of a multi layer structure as described above is characterized in that at least one additive is added to the dispersion. Preferably 3, more preferably 2, and most preferably 1 additive is added to the dispersion. The preferred function of the additive is the modification of physical properties in order to facilitate the preparation of multi layer structures. Particularly preferably the additive modifies the surface tension of the dispersion in order to enable film formation. A typical problem in context with the preparation of a multilayer structure using orthogonal solvents is the wetting of the solution or dispersion on the underneath layer.

Therefore, it is necessary to modify the solution or dispersion, for example its surface tension, before its use. It can be achieved by adding additional additives, for example wetting agents, dispersing agents, hydrophobing agents, adhesive agents etc. Further suitable additive can be referred to for example WO 2003/019693 A2. The important parameters for deposition techniques from solution or dispersion are for example viscosity, surface tension, concentration, molecular weight of the solution, and particle size of the dispersion, boiling point of solvent, etc.. Indeed, different deposition techniques demand different parameters. For the most widely used techniques, spin-coating and inkjet printing, they have some parameters in common; for example, they demand a viscosity most preferably in the range from 2 to15 mPas, a surface tension of < 40 mN/m, particles with a size of < 1 pm, and a boiling point of the solvent from 200 to 350°C, though the optimal condition may be different from each other depending on the method and the substrate used.

In further another embodiment, the present invention relates to a coating method using the emulsion and/or dispersion as described above and below. It is desirable to generate small structures or patterns in modern microelectronics to reduce cost (more devices/unit area), and power consumption. Patterning of the layer of the invention may be carried out, for example, by photolithography, electron beam lithography, nano-imprint lithography (as reported for example in Science (96), 272, 85-87), or "Dip- Pen" Nanolithography (as reported in Science (99), 283, 661-663). For use as thin layers in electronic or opto-electronic devices the organic functional materials or an emulsion or dispersion according to the present invention may be deposited by any suitable method. Liquid coating of devices such as OLEDs is more desirable than vacuum deposition techniques. Solution deposition methods are especially preferred. Preferred deposition techniques include, without limitation, dip coating, spin coating, inkjet printing, letter-press printing, screen printing, doctor blade coating, roller printing, reverse-roller printing, offset lithography printing, flexographic printing, web printing, spray coating, brush coating or pad printing, slot-die coating. Ink-jet printing is particularly preferred as it allows high resolution displays to be prepared.

Selected emulsions and /or dispersions according to the present invention may be applied to prefabricated device substrates by inkjet printing or microdispensing. Preferably industrial piezoelectric print heads such as but not limited to those supplied by Aprion, Hitachi-Koki, InkJet Technology, On Target Technology, Picojet, Spectra, Trident, Xaar may be used to apply the organic functional material layer to a substrate. Additionally semi industrial heads such as those manufactured by Brother, Epson, Konica, Seiko Instruments Toshiba TEC or single nozzle microdispensers such as those provided by Microdrop and Microfab may be used.

In order to be applied by inkjet printing or microdispensing, the emulsion and /or dispersion according to the present invention should be first prepared in a suitable solvent in the continuous phase. Solvents must fulfil the requirements stated above and must not have any detrimental effect on the chosen print head. In the case of water-based or other polar solvent- based emulsion, the use of such emulsions or dispersions are known in conjunction with desktop inkjet printers.

The emulsions and dispersions according to the present invention can be tailored with regard to their physical and chemical properties and may therefore be used in any kind of electronic device. The use of the emulsions and dispersions according the present invention or the dispersion according to the present invention obtained by a method according to the present invention for the preparation of electronic and opto-electronic devices is also subject of the present invention. The layer of a device prepared according to the teaching of the present invention have, due to the particle-related structure of the nanoparticles in dispersions or nanodroplets in emulsions a particular structure. This particular nano-structure, in turn, tremendously determines the structure of the corresponding layer and their beneficial opto-electronic characteristics of the layer itself and of the device as a whole. The present invention relates also to layer and multilayer structures obtainable by the use of a formulation according to the present invention. Moreover, the method for the preparation of a multilayer structure according to the present invention may be used to produce electronic and opto-electronic devices, which is an embodiment of the present invention.

Preferably the emulsions and dispersions according to the present invention may be used in opto-electronic devices, in which the absorption or emission of electromagnetic radiation preferably in the ultraviolet, visible or infrared part of the spectrum, plays a crucial role, such as light emitting devices, light sensors or light harvesting devices (e.g. photovoltaic cells). Preference is given to the use of emulsions and/or dispersions according to the present invention in electronic and opto-electronic devices selected from organic light emitting diodes (OLEDs), polymer light emitting diodes (PLEDs), fiber OLEDs, organic light emitting electrochemical cells (OLECs), organic field effect transistors (OFETs), thin film transistors (TFTs), organic solar cells (O-SCs), dye-sensitised solar cells (DSSCs), organic laser diodes (O-laser), organic integrated circuits (O-IC), radio frequency identification (RFID) tags, photodetectors, sensors, logic circuits, memory elements, capacitors, charge injection layers, Schottky diodes, planarising layers, antistatic films, conducting substrates or patterns, photoconductors, electrophotographic elements, organic light emitting transistors (OLETs), organic spintronic devices, and organic plasmon emitting devices (OPEDs).

The invention further relates to an electronic or opto-electronic device obtained by a method according to the present invention. Preferably the device is selected from organic light emitting diodes (OLEDs), polymer light emitting diodes (PLEDs), fiber OLEDs, organic light emitting electrochemical cells (OLECs), organic field effect transistors (OFETs), thin film transistors (TFTs), organic solar cells (O-SCs), dye-sensitised solar cells (DSSCs), organic laser diodes (O-laser), organic integrated circuits (O-IC), radio frequency identification (RFID) tags, photodetectors, sensors, logic circuits, memory elements, capacitors, charge injection layers, Schottky diodes, planarising layers, antistatic films, conducting substrates or patterns, photoconductors, electrophotographic elements, organic light emitting transistors (OLETs), organic spintronic devices, and organic plasmon emitting devices (OPEDs). Particularly preferably the device is an OLED, or an O-SC.

Preference is given to an OLED which is prepared by using at least one emulsion or dispersion according to the present invention, wherein said emulsion or dispersion comprises at least one organic functional material as outlined above.

A typical sequence of layers as found in an OLED and O-SC is, for example:

- optionally a first substrate,

- an anode layer,

- optionally a hole injection layer (HIL),

- optionally a hole transport layer (HTL) and/or an electron blocking layer (EBL),

- an active layer, which upon electrical or optical exciation, produces excitons,

- optionally an electron transport layer (ETL) and/or a hole blocking layer (HBL), - optionally an electron injection layer (EIL),

- a cathode layer, and

- optionally a second substrate.

The sequence of the given layer structure is exemplary. Other sequences are possible. Depending on the active layers in the above mentioned device, different opto-electronic devices will be obtained. In a first preferred embodiment, the active layer generates excitons upon electrical excitation through applying voltage between anode and cathode, and further emits light through radiative decay of the excitons. In general, this is called light emitting device. In another preferred embodiment, the active layer generates excitons through absorbing light, and further produces free charge carrier through exciton dissociation. In general, this is called photovoltaic or solar cell.

The term interlayer as used herein is defined as layer between the hole injection layer (or buffer layer) and the emissive layer in polymer light emitting diodes (PLEDs), being an electron blocking layer, as disclosed for example in WO 2004/084260 A2. The typical device structure of PLEDs with interlayer is shown in Figure 2. However one problem with this kind of device is that the interlayer is usually, at least in part, washed away upon coating the EML layer, which leads to a very thin layer. This process is not well-controlled in the prior art. It is highly desired to use ETL or HMB in PLEDs, as shown in Figure 3, in order to get better confinement of holes and excitons in the EML to achieve high efficiency and lifetime. In another preferred embodiment, the electronic device of the invention is soluble system based OLEDs, particularly PLEDs as disclosed for example in WO 2004/084260 A2, which comprises the multilayer structure as follows: anode/HIL/EML/Cathode, wherein the double-layer HIL/EML is made by using at leat one dispersion and one method for multilayer structure as described above.

The HIL is usually a transparent conductive polymer thin film comprising HIM. Preferred HIM are those mentioned above. The emissive materials may further comprise a blend or mixture of two or more different emitters, for example two emitters of different type and/or emitters that emit light of different colors. Thus, a device of the present invention may provide white light.

The device structure of the above mentioned further electronic device is clear to the skilled person in the art. Nevertheless, for the sake of clarity, references are made to some detailed device structures. Organic Plasmon emitting device is preferably referred to the device as reported by Koller et al. , in Nature Photonics (2008), 2, 684-687. The OPED is very similar as OLED as described above, except that at least one of anode and cathode should be capable to couple surface Plasmon from the emissive layer. It is preferred here that an OPED is prepared by using an emulsion or dispersion and the methods described herein.

One preferred organic spintronic device is a spin-valve device, as reported, e.g., by Z.H. Xiong et al., in Nature 2004, Vol. 427, 821, comprising two ferromagnetic electrodes and an organic layer between the two ferromagnetic electrodes. The ferromagnetic electrode is composed of Co, Ni, Fe, or alloys thereof, or ReMnOs or Cr0₂, wherein Re is rare earth element. It is preferred that at least one of the organic layers is coated from an emulsion or dispersion according the present invention.

Organic light emitting electrochemical cells (OLECs) comprise two electrodes, and a mixture or blends of electrolyte and fluorescent species in between, as firstly reported by Pei & Heeger in Science (1995), 269, 1086-1088. It is preferred here that an OLEC is prepared by using an emulsion or dispersion and the methods described above and below.

Dye-sensitized solar cells (DSSCs) comprise, in the sequence, an electrode/dye-sensitized T1O2 porous thin film/electrolyte/counter electrode, as firstly reported by O’Regan & Gratzel in Nature (1991), 353, 737-740. The liquid electrolyte can be replaced by a solid hole transport layer, as reported in Nature (1998), 395, 583-585.

The layer of a device prepared according to the teaching of the present invention have, due to the particle-related structure of the nanoparticles in dispersions or nanodroplets in emulsions a particular structure. This particular nano-structure, in turn, tremendously determines the structure of the corresponding layer and the beneficial opto-electronic characteristics of the layer itself and of the device as a whole. The present invention relates also to layer and multilayer structures obtainable by the use of a formulation according to the present invention. The present invention also relates to devices comprising said layer. Preferably the devices are opto electronic devices as outlined elsewhere in the present invention.

The present invention also relates to devices obtainable by the use of a formulation according to the present invention.

The formulations (dispersions, emulsions) of the present invention, devices comprising them and devices obtainable by using the said formulations can be used for any kind of light sources, which includes, but is not limited to, lightening and display applications. Light sources play also a crucial role in many therapeutic, cosmetic, prophylactic, and diagnostic applications. In some applications the function of light sources is solely directed to illuminate a display or the subject to be treated. In other cases the beneficial effect of light is exploited when human or animal subjects are treated. Thus, formulations, i.e. both emulsions and dispersions, according to the present invention can be used for the treatment, prophylaxis, and or diagnosis of therapeutic diseases and/or cosmetic conditions. This includes any kind of phototherapy, photodynamic therapy, and any combination of light therapy and therapies not using light such as drug therapies, commonly referred herein as to light therapy or light treatment. Many light treatments are directed to outer surfaces of the subject to be treated such as skin, wounds, mucosa, eye, hair, nail, nail beds, and gingival, and tongue, but light treatment can also be applied inside the subject in order to treat, e.g., the lungs, blood vessels, heart, breast, and other organs of the subject.

These diseases and/or conditions include, e.g., skin diseases, and skin- related conditions including skin-ageing, and cellulite, enlarged pores, oily skin, folliculitis, precancerous solar keratosis, skin lesion, aging, wrinkled and sun-damaged skin, crow’s feet, skin ulcers (diabetic, pressure, venous stasis), acne rosacea lesions, cellulite; photomodulation of sebaceous oil glands and the surrounding tissues; reducing wrinkles, acne scars and acne bacteria, inflammation, pain, wounds, psychological and neurological related diseases and conditions, edema, Pagets disease, primary and metastatic tumors, connective tissue disease, manipulation of collagen, fibroblast, and fibroblast derived cell levels in mammalian tissue, illuminating retina, neoplastic, neovascular and hypertrophic diseases, inflammation and allergic reactions, perspiration, sweating and hyperhydrosis from eccrine (sweat) or apocrine glands, jaundice, vitiligo, ocular neovascular diseases, bulimia nervosa, herpes, seasonal affective disorders, mood, sleep disorders, skin cancer, crigler naijar, atopic dermatitis, diabetic skin ulcers, pressure ulcers, bladder infections, relief of muscular pains, pain, stiffness of joints, reduction of bacteria, disinfection, disinfection of liquids, disinfection of beverages such as water, disinfection of nutrition, gingivitis, whitening teeth, treatment of teeth and tissue in mouth, wound healing.

The said formulations, devices comprising them, and devices obtainable by the use of formulations according to the present invention comprise preferably at least one organic electroluminescent compound which emits light in the range between 200 and 1000 nm, preferably between 300 and 1000 nm, more preferably between 300 and 950 nm, and most preferably between 400 and 900 nm.

It will be appreciated that variations to the foregoing embodiments of the present invention can be made while still falling within the scope of the present invention. Each feature disclosed in this specification, unless stated otherwise, may be replaced by alternative features serving the same, equivalent or similar purpose. Thus, unless stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

All of the features disclosed in this specification may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. In particular, the preferred features of the invention are applicable to all aspects of the invention and may be used in any combination. Likewise, features described in non-essential combinations may be used separately (not in combination).

It will be appreciated that many of the features described above, particularly of the preferred embodiments, are inventive in their own right and not just as part of an embodiment of the present invention. Independent protection may be sought for these features in addition to or alternative to any invention presently claimed.

The teaching as disclosed here can be abstracted und combined with other examples disclosed.

Other features of the invention will become apparent in the course of the following description of exemplary embodiments and drawings, which are given for illustration of the present invention and are not intended to be limiting thereof.

Brief Description of the Drawings

Fig. 1 shows the chemical structure of Span 20 and Tween 20 Fig. 2 shows the SFT curve of Span 20 dissolved in DEG Fig. 3 shows the SFT curve of Tween 20 dissolved in DEG Fig. 4 shows the SFT curve of Tween 20 dissolved in Water Fig. 5 shows the SFT curve of Span 20 and Tween 20 (6:94) dissolved in DEG Fig. 6 shows the SFT curve of Span 20 and Tween 20 dissolved in Water Fig. 7 shows the SFT curve of Span 20 and Tween 20 dissolved in DEG and Water (50:50)

Fig. 8 shows the stability times varying HLB using 1% surfactants in 3-PT and DEG (40:60) Fig. 9 shows the stability times depending on surfactant amount of Span 20 and Tween 20 at HLB 16.2

Fig. 10 shows the chemical structures of Brij 700 and Triton-X100 Fig. 11 shows the stability times depending on surfactant amount of Brij 700 and Triton-X100 at HLB 16.2 Fig. 12 shows the stability of rough HLB screening of Span 20 and Tween 20 in 3-PT and water

Fig. 13 shows the stability graph of Span 20 and Tween 20 in 3-PT and water

Fig. 14 shows the comparison of stability times varying HLB using the 3- PT, water or 3-PT, DEG, water system Working Examples

A) General Preparation Procedure

To ensure constant conditions, the weighing and other procedures of emulsion preparation are processed in the same way every time, for example keeping a constant weighing order. In our case the surfactants are weighed first, followed by the solvents. A small amount of a red emitter Nile Red is dissolved in the organic solvent 3-Phenoxytoluene (3-PT) before weighing. This is necessary, because both solvents are colorless and transparent and can^'t be distinguished otherwise.

After weighing, the emulsion is mixed with the UltraTurrax for 1 minute, followed by different investigations and results. The UltraTurrax is the best way to create emulsions as sheer forces create very small emulsion droplets. In general, 4 ml are used for each sample, if not mentioned different.

To create an emulsion, preferably at least two surfactants are needed to adjust HLB and two orthogonal solvents, which are found in the miscibility test below.

B) Miscibility tests of solvents

To find solvents for emulsion creation to start with, miscibility tests are done. Only solvents which are not miscible with each other are possible candidates.

In the first test, the miscibility of different solvents is screened. All samples are stirred for 10 minutes at 600 rpm and checked again 30 minutes after treatment. In Table 1 the results are summarized. All samples that are not miscible are possible candidates. Table 1 : Miscibility test of solvents

The rheological properties of the solvents summarized in Table 2 to identify candidates for the necessary printing properties such as a viscosity below 25 mPas. Table 2: Viscosity of possible emulsion solvents

As 3-PT is known to have good solubilizing properties for the EML materials, a low viscosity and high boiling point of 270°C and is not miscible with Diethyleneglycol (DEG) and 2,3-Butanediol, it is a good solvent to start with. Choosing the co-solvent with lower viscosity and boiling point similar 3-PT, the solvent duo to start with is chosen to 3-PT and DEG.

3-PT is the intended discontinuous phase containing the emitter, while DEG should be the continuous phase, orthogonal to HTL material.

It is important, that the inner phase has a higher boiling point than the outer phase. During drying, the continuous solvent should evaporate first so the droplets can form a continuous layer and build a uniform emitting layer after the inner solvent evaporates.

The ratio between 3-PT and DEG is set to 40:60, as more DEG than 3-PT ensures the DEG as continuous and 3-PT A as discontinuous phase. C) Choosing the surfactant system

Different surfactant couples are tested on the chosen solvent system 3-PT and DEG (40:60) in order is to identify a suitable surfactant couple to get a stable emulsion.

C1) Surfactant System Span 20 and Tween 20

The structure of both surfactants with corresponding HLB is shown in Figure 1. The big hydrophilic head of Tween 20 as the smaller hydrophilic group of Span 20, both connected through an ester bridge, is easy to recognize. Span 20 has a bigger lipophilic tail than Tween 20. a) Surface Tension (SFT) Curves and Micelle Formation

In addition to assessing the processability of an ink via inkjet printing, the determination of SFT gives information about the micelle formation in an emulsion. Investigations are done with Span 20 and Tween 20, when combined at HLB 16.2, equivalent to the most stable emulsions found. The SFT of DEG is 44.3 mN/m, while water has 72.8 mN/m. The purpose here is to determine the Critical Micelle Concentration (CMC) of these surfactants mixture.

For Span 20 in Solvent B the CMC lies around 0.5% surfactant amount, as shown in Figure 2. As Span 20 is not soluble in water at all, no comparison can be done. In the end, the surface tension is about 28 mN/m.

The same experiment was done for Tween 20, as shown in Figure 3. Tween 20 forms micelles earlier in water, as shown in Figure 4, than in DEG, as shown in Figure 3, more precisely 0.1% in water and 0.6% in DEG. Micelles are formed at higher concentration with Tween 20 compared to Span 20 in Solvent B. The higher solubility of Tween 20 in water could arise from the high HLB, standing for a big polar head and a small nonpolar tail, which creates micelles quicker in a polar solvent. Experiments combining both surfactants at HLB 16.2, the CMC in water is again very low at 0.1% total surfactant concentration, as shown in Figure 6, while in DEG the CMC is at 0.5% surfactant concentration, as shown in Figure 5. Referring to previous measurements of solely one of both surfactants, it seems Span 20 is responsible for early micelle formation in DEG, whereas Tween 20 forms micelles earlier in water.

Completing investigations on surface tension and CMC in DEG and water mixed 50:50, the CMC is again 0.1% surfactant concentration, as shown in Figure 7. Comparing to other experiments, first micelles are created through Tween 20 in the water phase.

Summarizing all experiments, it can be concluded that mixed micelles are built in a system containing DEG and water, as Tween 20 forms micelles in water first and Span 20 creates micelles earlier in DEG. SFT experiments with both surfactants are also described in literature with similar results. b) HLB screening in 3-PT and DEG The HLB of Span 20 and Tween 20 is screened in a 3-PT, DEG solvent system (40:60). For the HLB screening 1% surfactants was used, whereby the HLB is varied in the full range between Span 20 (HLB 8.6) and Tween 20 (HLB 16.7). From the collection of photographs taken in fixed time intervals it becomes clear, that the sample with surfactants at an HLB of 16.2 is most stable, as shown in Figure 8.

For this fixed ratio of surfactants, the absolute concentration for maximum stability was now assessed. As the conditions for this first experiment were not fully optimized, stability times could possibly vary. But stability of the samples varying in HLB will lead to equivalent relative results. The most stable sample always has HLB 16.2. c) Surfactant amount screening For the surfactant amount screening the HLB 16.2 is chosen by varying the surfactant amount from 0.1 % to 20%. The most stable emulsions are obtained, as shown in Figure 9, with 1% surfactants and HLB 16.2. This result was reproduced in a narrower HLB screening from HLB 15 to 16.7 using 1% surfactant amount. The stability is 7 hours.

The trend observed with varying surfactant amount is counterintuitive at first sight. Increasing the amount of Span 20 and Tween 20 is at first direct proportional to stability time, but increasing the surfactant amount further leads to indirect proportionality in terms of stability. This can happen due to the upper concentration limit of surfactants, where emulsion stability decreases due to rapid flocculation and creaming.

C2) Surfactant System Brij 700 and Triton-X100

As the stability of 7 hours is not sufficient to be applied for preparing printed OLEDs, one further surfactant system was investigated. The structures of Brij 700 and Triton-X100, as shown in Figure 10, are more linear compared to Span 20 and Tween 20, so a difference in micelle formation and stability is expected. Again, hydrophilic groups are framed blue, while lipophilic framed grey. a) HLB screening To ensure the solvent system HLB of 16.2 (see Span 20 & Tween 20), the HLB screening of Brij 700 and Triton-X100 is done.

The surfactant amount is chosen to 1%, while HLB is varying from 14.5 to 18.8. The HLB scale is confined by the surfactant HLB for Brij 700 (HLB 18.8) and Triton-X100 (HLB 13.5). Obviously, all emulsions are not stable as they are demixing after 1 minute. Of course, the sample with HLB 16.2 is most stable again, as it has the thinnest red layer on top. b) Surfactant concentration Varying the surfactant amount from 0.1% to 20% at HLB 16.2 shows, as depicted in Figure 11 , that using more surfactants is proportional to stability time. For this surfactant system, the emulsions are not stable and would need to improve substantially to consider printing emulsions with Brij 700 and Triton-X100. For the next experiments, these surfactants were no longer used. D) Varying solvent composition

As the most stable emulsion is only stable for 7 hours, the solvent system is changed to achieve more stable emulsions. Adding water to the previous 3-PT and DEG system (40:60) could influence stability due to the increased polarity of outer emulsion phase. First, the miscibility of water in 3-PT and in DEG was tested, showing that water is soluble in DEG, but not in 3-PT.

In a first experiment, DEG is totally substituted by water to see the effect on stability.

What is hard to capture in a picture is the precipitation occurring after a few days. It follows that this emulsion will not be printable, though stability time increased a lot, as shown in Figure 12.

In a more precise HLB screening around HLB 12.8 this system is investigated further. To see the results more clearly stability times are shown in Figure 13. There is no huge difference in stability in the range of HLB 11 to 15, where the most stable sample features HLB 13. But again, precipitates are building, so substituting DEG with water deteriorates the printability and a better solution needs to be found. An optimization of the total surfactant amount was not done, since there is precipitation already at 1 % total concentration. To obtain better results, a ternary system of 3-PT, DEG and water (40:30:30) is used. Again 1% of Span 20 and Tween 20 is used as surfactant. In a first HLB screening the obtained results are superior to the binary solvent mixture with water. The samples with HLB 12.8 and 16.2 are stable for more than 2 months (i.e. the test period), as shown in Figure 14.

Summarizing, emulsion stability improved vastly.

Claims

1. Formulation comprising at least one discontinuous phase and at least one continuous phase, wherein the at least one discontinuous phase contains at least one first solvent, wherein the at least one continuous phase contains at least one second organic solvent, wherein the formulation contains at least one surfactant, and wherein the at least one discontinuous phase comprises at least one organic functional material.

2. Formulation according to claim 1 , characterized in that the organic functional material is a small molecule organic functional material.

3. Formulation according to claim 2, characterized in that the small molecule organic functional material has a molecular weight of < 3000 g/mol.

4. Formulation according to one or more of claims 1 to 3, characterized in that the formulation comprises one discontinuous phase.

5. Formulation according to one or more of claims 1 to 4, characterized in that the formulation comprises one continuous phase.

6. Formulation according to one or more of claims 1 to 5, characterized in that the formulation comprises 1 to 6 organic functional materials.

7. Formulation according to one or more of claims 1 to 6, characterized in that the formulation comprises 2 to 5 surfactants.

8. Formulation according to one or more of claims 1 to 7, characterized in that the surfactants are nonionic surfactants.

9. Formulation according to one or more of claims 1 to 8, characterized in that the amount of the at least one surfactant is in the range from 0.1 to 20 wt% based on the overall weight of the formulation.

10. Formulation according to one or more of claims 1 to 9, characterized in that total HLB (hydrophilic lipophilic balance) of the at least one surfactant in the formulation is in the range from 10 to 19.

11. Formulation according to one or more of claims 1 to 10, characterized in that the at least one first solvent is selected from water, alcohol, glycols, ethers and/or glycol ethers.

12. Formulation according to one or more of claims 1 to 11 , characterized in that the at least one second organic solvent is selected from ketones, ethers, esters, amides, sulfur compounds, nitro compounds, hydrocarbons, halogenated hydrocarbons, aromatic or heteroaromatic hydrocarbons and halogenated aromatic or heteroaromatic hydrocarbons.

13. Formulation according to one or more of claims 1 to 12, characterized in that the at least one second organic solvent has a boiling point in the range from 200 to 350°C.

14. Formulation according to one or more of claims 1 to 13, characterized in that the organic functional materials are selected from hole injection materials (HIM), hole transport materials (FITM), hole blocking materials (FIBM), electron injection materials (EIM), electron transport materials (ETM), electron blocking materials (EBM), exciton blocking materials (ExBM), host materials, emitter materials, metal complexes, and dyes.

15. Method for the preparation of a formulation according to one or more of claims 1 to 14 comprising the following steps: a) preparing a first solution comprising at least one first solvent and at least one surfactant; b) preparing a second organic solution comprising at least one organic solvent and at least one organic functional material; c) mixing the first solution obtained in step (a) and the second solution obtained in step (b) in a specific ratio; and d) forming a formulation from the mixture of step (c) by a physical method.

16. Method for the preparation of a layer structure comprising the following steps:

(a) applying a first organic layer on a substrate, preferably by thermal evaporation or coating from solution or a dispersion; and

(b) applying a second organic layer to the first organic layer by coating the formulation according to one or more of claims 1 to 14 , characterised in that the first organic layer is insoluble or has a limited solubility of < 0.4 wt% at the working temperature in the solvent of the continuous phase of said formulation.

17. Method for the preparation of a layer structure comprising the following steps:

(a) applying a first organic layer on a substrate by coating the formulation according to one or more of claims 1 to 14 ; and

(b) applying a second organic layer to the first organic layer from an additional solution or another formulation according to one or more of claims 1 to 14; characterised in that the small molecule organic functional material in the first organic layer is insoluble or has a limited solubility of < 0.4 wt% at the working temperature in the solvent of the additional solution or the solvent of the continuous phase of the formulation.

18. Method according to claim 16 or 17, characterized in that at least one additive is added to the formulation.

19. Layer obtainable by the use of a formulation according to one or more of claims 1 to 14.

20. Use of the formulation according to one or more of claims 1 to 14 for the preparation of electronic and opto-electronic devices.

21. Use of the method according to one or more of claims 16 to 18 for the preparation of electronic and opto-electronic devices.

22. Use according to claim 20 or 21 , characterized in that the device is selected from organic light emitting diodes (OLEDs), polymer light emitting diodes (PLEDs), fiber OLEDs, organic light emitting electrochemical cells (OLECs), organic field effect transistors (OFETs), thin film transistors (TFTs), organic solar cells (O-SCs), dye-sensitised solar cells (DSSCs), organic laser diodes (O-laser), organic integrated circuits (O-IC), radio frequency identification (RFID) tags, photodetectors, sensors, logic circuits, memory elements, capacitors, charge injection layers, Schottky diodes, planarising layers, antistatic films, conducting substrates or patterns, photoconductors, electrophotographic elements, organic light emitting transistors (OLETs), organic spintronic devices, and organic plasmon emitting devices (OPEDs).

23. Electronic or opto-electronic device obtained by a method according to one or more of claims 16 to 18.