Field of the Invention The present invention relates to novel compositions comprising an organic semiconductor (OSC) and an organic solvent, to their use as conducting inks for the preparation of organic electronic (OE) devices, especially organic photovoltaic (OPV) cells and OLED devices, to methods for preparing OE devices using the novel formulations, and to OE devices and OPV cells prepared from such methods and compositions.

Background and Prior Art

When preparing OE devices like OFETs or OPV cells, in particular flexible devices, usually printing or coating techniques like inkjet printing, roll to roll printing, slot dye coating or fiexographic / gravure printing are used to apply the OSC layer. Based on low solubility of the most of the present organic compounds useful as OSC these techniques need the use of solvents in high amounts.

In order to improve the film forming ability binding agents or wetting agents can be used. These additives are especially needed with regard to light emitting materials and/or charge transporting materials having small molecular weight or polymeric compounds having a low molecular weight. However, these additives may impart drawbacks to the composition and/or the OE devices obtained thereof.

US 2007/0221885 relates to 3 solvent systems and is specifically relating to one solvent used to solubilise the active material, a second solvent that has a similar surface energy to the substrate and a third solvent which is used to make the other two solvents miscible. 3,4-dimethylanisole is mentioned within a list of solvents as a potential material to be used, it is not exemplified as one of the solvents. The main drive for this patent is to obtain printability onto low surface energy substrates.

WO 2006/122732 relates compositions, especially solutions, of at least one organic semiconductor emitting light from the triplet state, in an organic solvent or solvent mixture. The solvent may include 3,4-dimethylanisole. However, no example is provided. Furthermore, the document relates to polymeric organic semiconducting compounds. The prior art provides compositions being useful in order to process low molecular weight organic light emitting and charge transporting materials. However, it is a permanent desire to improve the performance of the OLED layer, such as efficiency, lifetime and sensitivity regarding oxidation or water.

In addition thereto, the formulation should enable a low-cost and easy printing process. The printing process should allow a high quality printing at high speed. It is therefore desirable to have improved formulations comprising an OSC that are suitable for the preparation of OE devices, especially thin film transistors, diodes, OLED displays and OPV cells, which allow the manufacture of high efficient OE devices having a high performance, a long lifetime and a low sensitivity against water or oxidation. One aim of the present invention is to provide such improved formulations. Another aim is to provide improved methods of preparing an OE device from such formulations. Another aim is to provide improved OE devices obtained from such formulations and methods. Further aims are immediately evident to the person skilled in the art from the following description.

Surprisingly it has been found that these aims can be achieved, and the above-mentioned problems can be solved, by providing methods, materials and devices as claimed in the present invention, especially by providing a process for preparing an OE device using a formulation of the present invention.

Summary of the Invention

The invention relates to a composition comprising one or more organic semiconducting compounds (OSC) having a molecular weight of at most 5000 g/mol, and one or more organic solvents, characterized in that said organic solvent is a dimethylanisole.

The invention further relates to the use of a composition as described above and below as coating or printing ink for the preparation of OLED devices, in particular for rigid and flexible OLED devices.

The invention further relates to a process of preparing an organic electronic (OE) device, comprising the steps of a) depositing the composition as described above and below onto a

substrate to form a film or layer, preferably by coating or printing, very preferably by ink jet printing, flexographic or gravure printing b) removing the solvent(s).

The invention further relates to an OE device prepared from a formulation and/or by a process as described above and below.

The OE devices include, without limitation, organic field effect transistors (OFET), integrated circuits (IC), thin film transistors (TFT), Radio Frequency Identification (RFID) tags, organic light emitting diodes (OLED), organic light emitting transistors (OLET), electroluminescent displays, organic photovoltaic (OPV) cells, organic solar cells (O-SC), flexible OPVs and O- SCs, organic laserdiodes (O-laser), organic integrated circuits (O-IC), lighting devices, sensor devices, electrode materials, photoconductors, photodetectors, electrophotographic recording devices, capacitors, charge injection layers, Schottky diodes, planarising layers, antistatic films, conducting substrates, conducting patterns, photoconductors, electro- photographic devices, organic memory devices, biosensors and biochips.

According to a preferred embodiment, the present invention provides organic light emitting diodes (OLED). OLED devices can for example be used for illumination, for medical illumination purposes, as signalling device, as signage devices, and in displays. Displays can be addressed using passive matrix driving, total matrix addressing or active matrix driving.

Transparent OLEDs can be manufactured by using optically transparent electrodes. Flexible OLEDs are assessable through the use of flexible substrates.

The formulations, methods and devices of the present invention provide surprising improvements in the efficiency of the OE devices and the production thereof. Unexpectedly, the performance, the lifetime and the efficiency of the OE devices can be improved, if these devices are achieved by using a composition of the present invention. Furthermore, it was surprisingly found that these formulations are suitable for printing

techniques, especially for flexographic and gravure printing. Furthermore, the composition of the present invention provides an astonishingly high level of film forming. Especially, the homogeneity and the quality of the films can be improved.

In addition thereto, the formulations enable a low-cost and easy printing process. The printing processes allow a high quality printing at high speed.

Detailed Description of the Invention The present formulation comprises at least one organic semiconducting compound (OSC). The OSC compounds can be selected from standard materials known to the skilled person and described in the literature. The OSC may be a monomeric compound (also referred to as "small molecule", as compared to a polymer or macromolecule), or a mixture, dispersion or blend containing one or more compounds selected from monomeric compounds.

According to an aspect of the present invention, the OSC is preferably a conjugated aromatic molecule, and contains preferably at least three aromatic rings, which can be fused or unfused. Unfused rings are connected e.g. via a linkage group, a single bond or a spiro-linkage.

Preferred monomeric OSC compounds contain one or more rings selected from the group consisting of 5-, 6- or 7-membered aromatic rings, and more preferably contain only 5- or 6-membered aromatic rings.

Each of the aromatic rings optionally contains one or more hetero atoms selected from Se, Te, P, Si, B, As, N, O or S, preferably from N, O or S. The aromatic rings may be optionally substituted with alkyl, alkoxy, polyalkoxy, thioalkyl, acyl,.aryl or substituted aryl groups, halogen, particularly fluorine, cyano, nitro or an optionally substituted secondary or tertiary alkylamine or aryl-amine represented by -N(R )(R ^y ), where R and R ^y independently of each other denote H, optionally substituted alkyl, optionally substituted aryl, alkoxy or polyalkoxy groups. Where R and/or R ^y denote alkyl or aryl these may be optionally fluorinated.

Preferred rings are optionally fused, or are optionally linked with a conjugated linking group such as -C(T ¹ )=C(T ² )-, -C≡C- -N(R ^Z )-, -N=N-, -(R ^Z )C=N-, -N=C(R ^Z )-, wherein T ¹ and T ² independently of each other denote H, CI, F, -C≡N- or a lower alkyl group, preferably a C^ alkyl group, and R ^z denotes H, optionally substituted alkyl or optionally substituted aryl. Where R ^z is alkyl or aryl these may be optionally fluorinated.

Preferred OSC compounds include small molecules (i.e. monomeric compounds), selected from condensed aromatic hydrocarbons such as tetracene, chrysene, pentacene, pyrene, perylene, coronene, or soluble substituted derivatives of the aforementioned; oligomeric para substituted phenylenes such as p-quaterphenyl (p-4P), p-quinquephenyl (p-5P), p- sexiphenyl (p-6P), or soluble substituted derivatives of the aforementioned; pyrazoline compounds; benzidine compounds; stilbene compounds;

triazines; substituted metallo- or metal-free porphines, phthalocyanines, fluorophthalocyanines, naphthalocyanines or fluoronaphthalocyanines; Ceo and C70 fullerenes or derivatives thereof; Λ/,Λ -dialkyl, substituted dialkyi, diaryl or substituted diaryl-1 ,4,5,8-naphthalenetetracarboxylic diimide and fluoro derivatives; N,N -dialkyi, substituted dialkyi, diaryl or substituted diaryl 3,4,9, 10-perylenetetracarboxylic diimide; bathophenanthroline;

diphenoquinones; 1 ,3,4-oxadiazoles; 11 ,1 1 ,12,12-tetracyanonaptho-2,6- quinodimethane; a,a'-bis(dithieno[3,2-b:2',3'-d]thiophene); 2,8-dialkyl, substituted dialkyi, diaryl or substituted diaryl anthradithiophene; 2,2'- bibenzo[1 ,2-b:4,5-b']dithiophene. Preferred compounds are those from the above list and derivatives thereof which are soluble.

Especially preferred OSC materials are substituted polyacenes, such as 6,13-bis(trialkylsilylethynyl)pentacene or derivatives thereof, such as 5, 11- bis(trialkylsilylethynyl)anthradithiophenes, as described for example in US 6,690,029, WO 2005/055248 A1 , or WO 2008/107089 A1. A further preferred OSC material is poly(3-substituted thiophene), very preferably poly(3-alkylthiophenes) (P3AT) wherein the alkyl group is preferably straight-chain and preferably has 1 to 12, most preferably 4 to 10 C-atoms, like e.g. poly(3-hexylthiophene). The composition according to the present invention can comprise between 0.01 and 20% by weight, preferably between 0.1 and 15% by weight, more preferably between 0.2 and 10% by weight and most preferably between 0.25 and 5% by weight of OSC materials or the corresponding blend. The percent data relate to 100% of the solvent or solvent mixture. The composition may comprise one or more than one, preferably 1 , 2, 3 or more than three OSC compounds.

The organic semiconductor compound used here is either a pure

component or a mixture of two or more components, at least one of which must have semiconducting properties. In the case of the use of mixtures, however, it is not necessary for each component to have semiconducting properties. Thus, for example, inert low-molecular-weight compounds can be used together with semiconduc-ting low-molecular-weight compounds. It is likewise possible to use non-conducting polymers, which serve as inert matrix or binder, together with one or more low-molecular-weight

compounds or further polymers having semiconduc-ting properties. For the purposes of this application, the potentially admixed non-conducting component is taken to mean an electro-optically inactive, inert, passive compound.

The organic semiconducting compound of the present invention preferably has a molecular weight of 5000 g/mol or less, especially a molecular weight of 2000 g/mol or less.

According to a special aspect of the present invention, the organic semiconduc-ting compound may preferably have a molecular weight of at least 550 g/mol, especially at least 800 g/mol, particularly at least 900 g/mol and more preferably at least 950 g/mol.

Astonishing improvements can be achieved with one or more organic semiconducting compounds having a high solubility. Preferred organic semiconducting compounds can comprise Hansen Solubility parameters of H _d in the range of 17.0 to 20.0 MPa ^{0 5} , H _p in the range of 2 to 10.0 MPa ^{0 5} and H _h in the range of 0.0 to 15.0 MPa ^{0 5} . More preferred organic semiconducting compounds comprise Hansen Solubility parameters of H _d in the range of 17.5 to 19.0 MPa ^{0 5} , H _p in the range of 3.5 to 8.0 MPa ^{0 5} and H _h in the range of 3.0 to 10.0 MPa ^{0 5} .

Surprising effects can be achieved with organic semiconducting

compounds having a radius of at least 3.0 MPa ^{0 5} , preferably at least 4.5 MPa ^{0 5} and more preferably at least 5.0 MPa ^{0 5} determined according to Hansen Solubility parameters.

The Hansen Solubility Parameters can be determined according to the Hansen Solubility Parameters in Practice HSPiP 3 ^rd edition, (Software version 3.0.38) with reference to the Hansen Solubility Parameters: A User's Handbook, Second Edition, C. M. Hansen (2007), Taylor and Francis Group, LLC) as supplied by Hanson and Abbot et al.

The positions H _d , H _p and H _h are the coordinates in 3 dimensional space for the centre of the organic semiconducting compound, whilst the radius, gives the distance that the solubility extends, ie if the radius is large it will encompass more solvents that would dissolve the material and conversely if it was small then a restricted number of solvents would solubilise the organic semiconducting compound.

According to a special aspect of the present invention the organic semiconduc-ting compound may comprise a high glass transition temperature. Preferably, the organic semiconducting compound may have a glass transition temperature of at least 70°C, especially at least 100°C and more preferably at least 125°C determined according to DIN 51005. Preferred organic semiconducting compounds may comprise a groups providing solubility to the compounds. In addition thereto, other functional compounds useful for preparing OE devices, especially OLED devices may comprise solubilising groups. Other functional compounds include, e.g. host materials, hole-transport materials, electron- or exciton-blocking materials, matrix materials for fluorescent or phosphorescent compounds, hole- blocking materials or electron-transport materials.

Accordingly, these compounds may preferably be represented by the general formula (I)

wherein

A is a functional structure element,

B is a solubilising structure element and

k is a integer in the range of 1 to 20,

and

said solubilising structure element B has the general formula (L-l)

wherein

Ar ³ represents aryl or heteroaryl group which has from 4 to 120 carbon atoms and may be substituted by one or more arbitrary residues R,

R ^a represents hydrogen, a straight chain alkyl, alkoxy or thioalkoxy group having 1 to 40 carbon atoms or a branched or cyclic alkyl, alkoxy or thioalkoxy group having 3 to 40 carbon atoms, especially an optionally substituted C7-C40 alkylaryloxy group; an optionally substituted C2-C40 alkoxycarbonyl group; an optionally substituted C7-C40 aryloxycarbonyl group; a cyano group (-CN); a carbamoyl group (-C(=0)NH ₂ ); a haloformyl group (-C(=0)-X, wherein X represents a halogen atom); a formyl group (-C(=0)-H); an isocyano group; an isocyanate group; a thiocyanate group or a thioisocyanate group; an optionally substituted amino group; a hydroxy group; a nitro group; a CF3 group; a halo group (CI, Br, F); or an optionally substituted silyl or alkynylsilyl group; or a curable group or a substituted or unsubstituted aromatic or hetero aromatic ring system having 5 to 60 ring atoms, or a aryloxy or heteroaryloxy group having 5 to 60 ring atoms, or a combination thereof, wherein one or more of these groups R ^a may form a mono or polycyclic aliphatic or aromatic ring system together and/or the ring to which the group R ^a is bound; and

I is 0, 1, 2, 3 or 4;

wherein the dotted bond represents the bond to the functional structural element A.

Preferably, the index k of the general formula (I) is an integer of 2 or more, more preferably 3 or more.

For the purposes of this invention, an aryl group contains at least 6 C atoms; for the purposes of this invention, a heteroaryl group contains at least 2 C atoms and at least one heteroatom, with the proviso that the sum of C atoms and heteroatoms is at least 5. The heteroatoms are preferably selected from N, O and/or S. An aryl group or heteroaryl group here is taken to mean either a simple aromatic ring, i.e. benzene, or a simple het- eroaromatic ring, for example pyridine, pyrimidine, thiophene, etc., or a condensed aryl or heteroaryl group, for example naphthalene, anthracene, pyrene, quinoline, isoquinoline, etc.

For the purposes of this invention, an aromatic ring system contains at least 6 C atoms in the ring system. For the purposes of this invention, a hetero- aromatic ring system contains at least 2 C atoms and at least one hetero- atom in the ring system, with the proviso that the sum of C atoms and heterbatoms is at least 5. The heteroatoms are preferably selected from N, O and/or S. For the purposes of this invention, an aromatic or heteroaroma- tic ring system is intended to be taken to mean a system which does not necessarily contain only aryl or hetero-aryl groups, but instead in which, in addition, a plurality of aryl or heteroaryl groups may be interrupted by a short non-aromatic unit (preferably less than 10% of the atoms other than H), such as, for example, an sp ³ -hybridised C, N or O atom or a carbonyl group. Thus, for example, systems such as 9,9'-spirobifluorene, 9,9-diaryl- fluorene, triarylamine, diaryl ether, stilbene, benzophenone, etc., are also intended to be taken to be aromatic ring systems for the purposes of this invention. An aromatic or heteroaromatic ring system is likewise taken to mean systems in which a plurality of aryl or heteroaryl groups are linked to one another by single bonds, for example biphenyl, terphenyl or bipyridine.

For the purposes of the present invention, a Ci- to C ₄ o-alkyl group, in which, in addition, individual H atoms or CH ₂ groups may be substituted by the above-mentioned groups, is particularly preferably taken to mean the radicals methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, s-butyl, t-butyl, 2-methylbutyl, n-pentyl, s-pentyl, t-pentyl, 2-pentyl, neopentyl, cyclopentyl, n-hexyl, s-hexyl, t-hexyl, 2-hexyl, 3-hexyl, neohexyl, cyclohexyl, 2-methyl- pentyl, n-heptyl, 2-heptyl, 3-heptyl, 4-heptyl, cycloheptyl, 1-methylcyclo- hexyl, n-octyl, 2-ethylhexyl, cyclooctyl, 1-bicyclo[2.2.2]octyl, 2-bicyclo- [2.2.2]octyl, 2-(2,6-dimethyl)octyl, 3-(3,7-dimethyl)octyl, trifluoromethyl, pentafluoroethyl and 2,2,2-trifluoroethyl. A C ₂ - to C ₄₀ -alkenyl group is preferably taken to mean ethenyl, propenyl, butenyl, pentenyl, cyclopentenyl, hexenyl, cyclohexenyl, heptenyl, cycloheptenyl, octenyl or cyclooctenyl. A C ₂ - to C ₄ o-alkynyl group is preferably taken to mean ethynyl, propynyl, butynyl, pentynyl, hexynyl, heptynyl or octynyl. A d- to C ₄₀ -alkoxy group is preferably taken to mean methoxy, trifluoromethoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, i-butoxy, s-butoxy, t-butoxy or 2-methylbutoxy. An aromatic or heteroaromatic ring system having 5 - 60 aromatic ring atoms, which may also in each case be substituted by the above-mentioned radicals R and which may be linked to the aromatic or heteroaromatic ring system via any desired positions, is taken to mean, in particular, groups derived from benzene, naphthalene, anthracene, phenanthrene, benz- anthracene, benzophenanthrene, pyrene, chrysene, perylene, fluoranthene, benzofluoranthene, naphthacene, pentacene, benzopyrene, biphenyl, bi- phenylene, terphenyl, terphenylene, fluorene, benzofluorene,

dibenzofluorene, spirobifluorene, dihydrophenanthrene, dihydropyrene, tetrahydropyrene, cis- or trans-indenofluorene, cis- or trans-monobenzo- indenofluorene, cis- or trans-dibenzoindenofluorene, truxene, isotruxene, spirotruxene, spiroisotruxene, furan, benzofuran, isobenzofuran, dibenzo- furan, thiophene, benzothiophene, isobenzothiophene, dibenzothiophene, pyrrole, indole, isoindole, carbazole, pyridine, quinoline, isoquinoline, acridine, phenanthridine, benzo-5,6-quinoline, benzo-6,7-quinoline, benzo- 7,8-quinoline, phenothiazine, phenoxazine, pyrazole, indazole, imidazole, benzimidazole, naphthimidazole, phenanthrimidazole, pyridimidazole, pyrazinimidazole, quinoxalinimidazole, oxazole, benzoxazole, naphthoxa- zole, anthroxazole, phenanthroxazole, isoxazole, 1 ,2-thiazole, 1 ,3-thiazole, benzothiazole, pyridazine, benzopyridazine, pyrimidine, benzopyrimidine, quinoxaline, 1 ,5-diazaanthracene, 2,7-diazapyrene, 2,3-diazapyrene, 1 ,6- diazapyrene, 1 ,8-diazapyrene, 4,5-diazapyrene, 4,5,9, 10-tetraazaperylene, pyrazine, phenazine, phenoxazine, phenothiazine, fluorubin, naphthyridine, azacarbazole, benzocarboline, phenanthroline, 1 ,2,3-triazole, 1 ,2,4-triazole, benzotriazole, 1 ,2,3-oxadiazole, 1 ,2,4-oxadiazole, 1 ,2,5-oxadiazole, 1 ,3,4- oxadiazole, 1 ,2,3-thiadiazole, 1 ,2,4-thiadiazole, 1 ,2,5-thiadiazole, 1 ,3,4- thiadiazole, 1 ,3,5-triazine, 1 ,2,4-triazine, 1 ,2,3-triazine, tetrazole, 1 ,2,4,5- tetrazine, 1 ,2,3,4-tetrazine, 1 ,2,3,5-tetrazine, purine, pteridine, indolizine and benzothiadiazole.

A curable group means a functional group being able to react irreversible in order to form a cross-linked material being insoluble. The cross-linking can be sustained by heating or UV-, microwave, x-ray or electron beam irradiation. Preferably, only a small amount of by-products is formed.

Furthermore, the curable groups enable an easy cross-linking such that only small amounts of energy is needed in order to obtain cross-linking (e.g.

< 200°C for thermic crosslinking).

Examples for curable groups are units comprising a double bond, a triple bond, precursors for forming double and/or triple bonds, units comprising a heterocyclic residue being able for addition polymerization.

Curable groups include e.g. vinyl, alkenyl, preferably ethenyl and propenyl, C _4- 2o-cycloalkenyl, azid, oxirane, oxetane, di(hydrocarbyl)amino, cyanat ester, hydroxy, glycidyl ether, Ci-io-alkylacrylat, Ci-10-alkylmeth acrylat, alkenyloxy, preferably ethenyloxy, perfluoro alkenyloxy, preferably perfluorethenyloxy, alkinyl, preferably ethinyl, maleic imid, tri(Ci-4)- alkylsiloxy and tri(C _1-4 )-alkylsilyl. Especially preferred are vinyl und alkenyl.

Examples of the solubilising structure element B having the general formula (L-l) include

L (l) 1 L (l) 2 L CD 3 L (l) 4 ln the formulae above, the dotted bond represents the bond to the functional structural element A.

More preferably, the organic semiconducting compounds and/or other functional compounds may be represented by the general formula (II) wherein

A is a functional structure element,

B is a solubilising structure element and

k is a integer in the range of 1 to 20,

and

said solubilising structure element B has the general formula (L-ll)

wherein

Ar ^b , Ar ^c each independently are the same or different and each

independently represents aryl or heteroaryl group which has from 4 to 60 carbon atoms and may be substituted by one or more arbitrary residues R,

X each independently represents N or CR ^b , preferably CH,

R ^a , R ^b each independently are the same or different represents

hydrogen, a straight chain alkyl, alkoxy or thioalkoxy group having 1 to 40 carbon atoms or a branched or cyclic alkyl, alkoxy or thioalkoxy group having 3 to 40 carbon atoms, especially an optionally substituted C ₇ -C ₄₀ alkylaryloxy group; an optionally substituted C ₂ -C ₄ o alkoxycarbonyl group; an optionally substituted C -C ₄ o aryloxycarbonyl group, a cyano group (-CN); a carbamoyl group (-C(=0)NH ₂ ); a haloformyl group (-C(=0)-X, wherein X represents a halogen atom); a formyl group

(-C(=0)-H); an isocyano group; an isocyanate group; a thiocyanate group or a thioisocyanate group; an optionally substituted amino group; a hydroxy group; a nitro group; a CF ₃ group; a halo group (CI, Br, F); or an optionally substituted silyl or alkynylsilyl group; or a curable group or a substituted or unsubstituted aromatic or hetero aromatic ring system having 5 to 60 ring atoms, or a aryloxy or heteroaryloxy group having 5 to 60 ring atoms, or a combination thereof, wherein one or more of these groups R ^a and/or R ^b may form a mono or polycyclic aliphatic or aromatic ring system together and/or the ring to which the group R ^a is bound; and

I is 0, 1 , 2, 3 or 4;

wherein the dotted bond represents the bond to the functional structural element A.

Preferably, the index k of the general formula (II) is an integer of 2 or more, more preferably 3 or more.

In the compounds according to formulae (I) and/or (II) above, the residue R can preferably be selected from F, CI, Br, I, N(Ar) ₂ , N(R') ₂ , CN, N0 ₂ , Si(R') ₃ , B(OR') ₂ , C(=0)Ar, C(=0)R', P(=0)(Ar) ₂ , P(=0)(R') ₂ , S(=0)Ar, S(=0)R\ S(=0) ₂ Ar, S(=0) ₂ R', -CR'=CR'Ar, OS0 ₂ R', a straight-chain alkyl, alkoxy oder thioalkoxy group having 1 to 40 C atoms, preferably 1 to 20 C atoms or a branched or cyclic alkyl, alkoxy or thioalkoxy group having 3 to 40 C atoms, preferably 3 to 20 C atoms, each of which may be substituted by one or more radicals R', where one or more non adjacent CH ₂ groups may be replaced by R'C=CR\ C≡C, Si(R') ₂ , Ge(R') ₂ , Sn(R') ₂ , C=0, C=S, C=Se, C=NR\ P(=0)(R'), SO, S0 ₂ , NR', O, S or CONR' and where one or more where one or more H atoms may be replaced by F, CI, Br, I, CN or N0 ₂ , a curable group or a aromatic or heteroaromatic ring system having 5 to 60 ring atoms, which may be substituted by one or more radicals R', or a aryloxy or aeteroaryloxy group having 5 to 60 ring atoms, which may be substituted by one or more radicals R', or a combination of these systems; two or more substituents R here may also form a mono- or polycyclic, aliphatic or aromatic ring system with one another, wherein R' identically or differently on each occurrence represents H or a aliphatic or aromatic carbyl group having 1 to 20 C atoms and Ar represents a aryl or a heteroaryl group having 2 to 30 C atoms.

More preferably, the organic semiconducting compounds and/or other functional compounds may be represented by the general formula (III) wherein

A is a functional structure element,

B is a solubilising structure element and

k is a integer in the range of 1 to 20,

and

said solubilising structure element B has the general formula (L-lll)

(L-lll) wherein

R ^a , R ^b , R ^c , R ^d each independently are the same or different represents hydrogen, a straight chain alkyl, alkoxy or thioalkoxy group having 1 to 40 carbon atoms or a branched or cyclic alkyl, alkoxy or thioalkoxy group having 3 to 40 carbon atoms, especially an optionally substituted C ₇ -C ₄ o alkylaryloxy group; an optionally substituted C2-C ₄ o alkoxycarbonyl group; an optionally substituted C ₇ -C ₄₀ aryloxycarbonyl group; a cyano group (-CN); a carbamoyl group (-C(=0)NH ₂ ); a haloformyl group (-C(=0)-X, wherein X represents a halogen atom); a formyl group (-C(=0)- H); an isocyano group; an isocyanate group; a thiocyanate group or a thioisocyanate group; an optionally substituted amino group; a hydroxy group; a nitro group; a CF ₃ group; a halo group (CI, Br, F); or an optionally substituted silyl or alkynylsilyl group; or a curable group or a substituted or unsubstituted aromatic or hetero aromatic ring system having 5 to 60 ring atoms, or a aryloxy or heteroaryloxy group having 5 to 60 ring atoms, or a combination thereof, wherein one or more of these groups R ^a , R ^b , R ^c and/or R ^d may form a mono or polycyclic aliphatic or aromatic ring system together and/or the ring to which the groups R ^a , R ^b , R ^c and/or R ^d are bound;

I is 0, 1 , 2, 3 or 4;

m is 0, 1 , 2 or 3; and

n, o each independently are the same or different represents 0, 1 , 2,

3, 4 or 5;

wherein the dotted bond represents the bond to the functional structural element A.

Preferably, the residues R ^a , R ^b , R°, R ^d represent hydrogen (I, m, n und o = 0), a straigth chain alkyl or alkoxy group having 1 to 20 carbon atoms or a branched or cyclic alkyl or alkoxy group having 3 to 40 carbon atoms. Preferably, the index k of the general formula (III) is an integer of 2 or more, more preferably 3 or more.

According to a preferred aspect of the present invention, the weight ratio of the functional structure element A to the solubilizing structure element B in the formulae (I), (II) and (III) is preferably in the range of 2:1 to 1 :20, more preferably 1 :1 to 1 :3.

Preferred solubilising structure elements B include e.g. structure elements according to the following formulae:

Preferred solubilising structure elements B include e.g. structure elements according to the following formulae:

(L-llla1) ^■A (L-llla2) -20-

(L-llla1 1) (L-llla12)

(L-lllb1) (L-lllb2)

In the formulae above, the dotted bond represents the bond to the functional structural element A.

According to a special embodiment of the present invention, the OSC can be used for example as the active channel material in the semiconducting channel of an OFET, or as a layer element of an organic rectifying diode.

In case of OFET devices, where the OFET layer contains an OSC as the active channel material, it may be an n- or p-type OSC. The semiconducting channel may also be a composite of two or more OSC compounds of the same type, i.e. either n- or p-type. Furthermore, a p-type channel OSC compound may for example be mixed with an n-type OSC compound for the effect of doping the OSC layer. Multilayer semiconductors may also be used. For example, the OSC may be intrinsic near the insulator interface and a highly doped region can additionally be coated next to the intrinsic layer.

Preferred OSC compounds have a FET mobility of greater than 1x10 ^"5 cm ² V ^"1 s ^" \ very preferably greater than 1x10 ^"2 cm ² \A ¹ s ^"1 .

Especially preferred monomeric OSC compounds are selected from the group consisting of substituted oligoacenes such as pentacene, tetracene or anthracene, or heterocyclic derivatives thereof, like bis(trialkylsilyl- ethynyl) oligoacenes or bis(trialkylsilylethynyl) heteroacenes, as disclosed for example in US 6,690,029, WO 2005/055248 A1 or US 7,385,221. Particularly preferred monomeric OSC compounds are selected from formula M1 (polyacenes):

wherein each of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹ and R ¹² , which may be the same or different, independently represents: hydrogen; an optionally substituted Ci-C ₄₀ carbyl or hydrocarbyl group; an optionally substituted Ci-C ₄₀ alkoxy group; an optionally substituted C6-C40 aryloxy group; an optionally substituted C7-C40 alkylaryloxy group; an optionally substituted C ₂ -C ₄ o alkoxycarbonyl group; an optionally substituted C7-C40 aryloxycarbonyl group; a cyano group (-CN); a carbamoyl group

(-C(=0)NH ₂ ); a haloformyl group (-C(=0)-X, wherein X represents a halogen atom); a formyl group (-C(=0)-H); an isocyano group; an isocyanate group; a thiocyanate group or a thioisocyanate group; an optionally substituted amino group; a hydroxy group; a nitro group; a CF ₃ group; a halo group (CI, Br, F); or an optionally substituted silyl or alkynylsilyl group; and wherein independently each pair of R ¹ and R ² , R ² and R ³ , R ³ and R ⁴ , R ⁷ and R ⁸ , R ⁸ and R ⁹ , R ⁹ and R ¹⁰ , is optionally cross-bridged to form a C ₄ -C ₄₀ saturated or unsaturated ring, which saturated or unsaturated ring may be intervened by an oxygen atom, a sulphur atom or a group of the formula - N(R ^a )-, wherein R ^a is a hydrogen atom or an optionally substituted hydrocarbon group, or may optionally be substituted; and wherein one or more of the carbon atoms of the polyacene skeleton may optionally be substituted by a heteroatom selected from N, P, As, O, S, Se and Te; and wherein independently any two or more of the substituents R ¹ -R ¹² which are located on adjacent ring positions of the polyacene may, together, optionally constitute a further C -C ₄₀ saturated or unsaturated ring optionally intervened by O, S or -N(R ^a ), where R ^a is as defined above, or an aromatic ring system, fused to the polyacene; and wherein n is 0, 1 , 2, 3 or 4 preferably n is 0, 1 or 2, most preferably n is 0 or 2, meaning that the polyacene compound is a pentacene compound (if n=2) or a "pseudo pentacene" compound (if n=0).

Preferably, the compound according to formula M1 meets the requirements of formula (I), formula (II) and/or formula (III) and comprise a solubilizing structure element of formulae (L-l), (L-ll) and (L-lll), respectively.

Very preferred are compounds of formula M1 a (substituted pentacenes): wherein R ¹ , R ² , R ³ , R ⁴ ,R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹⁵ , R ¹⁶ , R ¹⁷ each independently are the same or different and each independently represents: H; an optionally substituted Ci-C ₄₀ carbyl or hydrocarbyl group; an optionally substituted Ci- C ₄₀ alkoxy group; an optionally substituted C ₆ -C ₄₀ aryloxy group; an optionally substituted C7-C40 alkylaryloxy group; an optionally substituted C ₂ -C ₄ o alkoxycarbonyl group; an optionally substituted C ₇ -C ₄ o aryloxy- carbonyl group; a cyano group (-CN); a carbamoyl group (-C(=0)NH ₂ ); a haloformyl group (-C(=0)-X, wherein X represents a halogen atom); a formyl group (-C(=0)-H); an isocyano group; an isocyanate group; a thiocyanate group or a thioisocyanate group; an optionally substituted amino group; a hydroxy group; a nitro group; a CF ₃ group; a halo group (CI, Br, F); or an optionally substituted silyl group; and A represents Silicon or Germanium; and wherein independently each pair of R ¹ and R ² , R ² and R ³ , R ³ and R ⁴ , R ⁷ and R ⁸ , R ⁸ and R ⁹ , R ⁹ and R ¹⁰ , R ¹⁵ and R ¹⁶ , and R ¹⁶ and R ¹⁷ is optionally cross-bridged with each other to form a C4-C40 saturated or unsaturated ring, which saturated or unsaturated ring is optionally intervened by an oxygen atom, a sulphur atom or a group of the formula -N(R ^a )-, wherein R ^a is a hydrogen atom or a hydrocarbon group, or is optionally substituted; and wherein one or more of the carbon atoms of the polyacene skeleton is optionally substituted by a heteroatom selected from N, P, As, O, S, Se and Te.

Preferably, the compound according to formula M1a meets the

requirements of formula (I), formula (II) and/or formula (III) and comprise a solubilizing structure element of formulae (L-l), (L-ll) and (L-lll),

respectively.

Further preferred are compounds of formula M1b (substituted

heteroacenes):

wherein R ² , R ³ , R ⁸ , R ⁹ , R ¹⁵ , R ¹⁶ , R ⁷ each independently are the same or different and each independently represents: H; an optionally substituted Ci-C ₄₀ carbyl or hydrocarbyl group; an optionally substituted C C ₄ o alkoxy group; an optionally substituted C ₆ -C ₄₀ aryloxy group; an optionally substituted C ₇ -C ₄₀ alkylaryloxy group; an optionally substituted C ₂ -C ₄₀ alkoxycarbonyl group; an optionally substituted C ₇ -C ₄₀ aryloxycarbonyl group; a cyano group (-CN); a carbamoyl group (-C(=0)NH ₂ ); a haloformyl group (-C(=0)-X, wherein X represents a halogen atom); a formyl group (-C(=0)-H); an isocyano group; an isocyanate group; a thiocyanate group or a thioisocyanate group; an optionally substituted amino group; a hydroxy group; a nitro group; a CF ₃ group; a halo group (CI, Br, F); or an optionally substituted silyl group; and A represents Silicon or Germanium; and wherein independently each pair of R ² and R ³ , R ⁸ and R ⁹ , R ¹⁵ and R ¹⁶ , and R ⁵ and R ⁷ is optionally cross-bridged with each other to form a C4-C40 saturated or unsaturated ring, which saturated or unsaturated ring is optionally intervened by an oxygen atom, a sulphur atom or a group of the formula -N(R ^a )-, wherein R ^a is a hydrogen atom or a hydrocarbon group, and is optionally substituted; and wherein one or more of the carbon atoms of the polyacene skeleton is optionally substituted by a heteroatom selected from N, P, As, O, S, Se and Te.

Especially preferred are compounds of subformula M1b, wherein at least one pair of R ² and R ³ , and R ⁸ and R ⁹ is cross-bridged with each other to form a C4-C40 saturated or unsaturated ring, which is intervened by an oxygen atom, a sulphur atom or a group of the formula -N(R ^a )-, wherein R ^a is a hydrogen atom or a hydrocarbon group, and which is optionally substituted.

Preferably, the compound according to formula M1b meets the

requirements of formula (I), formula (II) and/or formula (III) and comprise a solubilizing structure element of formulae (L-l), (L-ll) and (L-lll),

respectively.

Especially preferred are compounds of subformula M1b1 (silylethynylated heteroacenes):

wherein

one of Y and Y ² denotes -CH= or =CH- and the other denotes -X-, one of Y ³ and Y ⁴ denotes -CH= or =CH- and the other denotes -X-,

X is -O-. -S-. -Se- or -NR"'-,

R' is H, F, CI, Br, I, CN, straight-chain or branched alkyl or alkoxy that have 1 to 20, preferably 1 to 8 C-atoms and are optionally fluorinated or perfluorinated, optionally fluorinated or perfluorinated aryl having 6 to 30 C-atoms, preferably C ₆ F ₅ , or C0 ₂ R"", with R"" being H, optionally fluorinated alkyl having 1 to 20 C-atoms or optionally fluorinated aryl having 2 to 30, preferably 5 to 20 C-atoms,

R" is, in case of multiple occurrence independently of one another, cyclic, straight-chain or branched alkyl or alkoxy that have 1 to 20, preferably 1 to 8 C-atoms, or aryl having 2 to 30 C-atoms, all of which are optionally fluorinated or perfluorinated, with SiR" ₃ preferably being trialkylsilyl,

R'" is H or cyclic, straight-chain or branched alkyl with 1 to 10 C-atoms, preferably H,

m is O or l ,

o is O or l .

Especially preferred are compounds of formula M1b1 wherein m and o are 0, and/or X is S, and/or R' is F. ln a preferred embodiment the compound of subformula 1b1 is provided and used as a mixture of the anti- and syn-isomers of the following formulae

wherein X, R, R\ R" m and o have independently of each other one of the meanings given in formula 1b1 or one of the preferred meanings given above and below, X is preferably S, and m and o are preferably 0.

The term "carbyl group" as used above and below denotes any monovalent or multivalent organic radical moiety which comprises at least one carbon atom either without any non-carbon atoms (like for example -C≡C-), or optionally combined with at least one non-carbon atom such as N, O, S, P, Si, Se, As, Te or Ge (for example carbonyl etc.)- The term "hydrocarbyl group" denotes a carbyl group that does additionally contain one or more H atoms and optionally contains one or more hetero atoms like for example N, O, S, P, Si, Se, As, Te or Ge.

A carbyl or hydrocarbyl group comprising a chain of 3 or more C atoms may also be straight-chain, branched and/or cyclic, including spiro and/or fused rings.

Preferred carbyl and hydrocarbyl groups include alkyl, alkoxy,

alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy and alkoxycarbonyloxy, each of which is optionally substituted and has 1 to 40, preferably 1 to 25, very preferably 1 to 18 C atoms, furthermore optionally substituted aryl or aryloxy having 6 to 40, preferably 6 to 25 C atoms, furthermore alkylaryloxy, arylcarbonyl, aryloxycarbonyl, arylcarbonyloxy and aryloxycarbonyloxy, each of which is optionally substituted and has 6 to 40, preferably 7 to 40 C atoms, wherein all these groups optionally contain one or more hetero atoms, especially selected from N, O, S, P, Si, Se, As, Te and Ge.

The carbyl or hydrocarbyl group may be a saturated or unsaturated acyclic group, or a saturated or unsaturated cyclic group. Unsaturated acyclic or cyclic groups are preferred, especially aryl, alkenyl and alkynyl groups (especially ethynyl). Where the C1-C40 carbyl or hydrocarbyl group is acyclic, the group may be straight-chain or branched. The C C o carbyl or hydrocarbyl group includes for example: a Ci-C ₄₀ alkyl group, a C ₂ -C ₄ o alkenyl group, a C ₂ -C ₄₀ alkynyl group, a C ₃ -C ₄ o allyl group, a C ₄ -C ₄₀ alkyldienyl group, a C ₄ -C ₄₀ polyenyl group, a C ₆ -Ci ₈ aryl group, a C ₆ -C ₄₀ alkylaryl group, a C ₆ -C ₄₀ arylalkyl group, a C ₄ -C ₀ cycloalkyl group, a C ₄ -C ₄₀ cycloalkenyl group, and the like. Preferred among the foregoing groups are a C C ₂ o alkyl group, a C ₂ -C ₂ o alkenyl group, a C ₂ -C ₂₀ alkynyl group, a C ₃ - C ₂ o allyl group, a C ₄ -C ₂ o alkyldienyl group, a C ₆ -C ₁₂ aryl group and a C ₄ -C ₂₀ polyenyl group, respectively. Also included are combinations of groups having carbon atoms and groups having hetero atoms, like e.g. an alkynyl group, preferably ethynyl, that is substituted with a silyl group, preferably a trialkylsilyl group.

Aryl and heteroaryl preferably denote a mono-, bi- or tricyclic aromatic or heteroaromatic group with up to 25 C atoms that may also comprise condensed rings and is optionally substituted with one or more groups L, wherein L is halogen or an alkyl, alkoxy, alkylcarbonyl or alkoxycarbonyl group with 1 to 12 C atoms, wherein one or more H atoms may be replaced by F or CI.

Especially preferred aryl and heteroaryl groups are phenyl in which, in addition, one or more CH groups may be replaced by N, naphthalene, thiophene, selenophene, thienothiophene, dithienothiophene, fluorene and oxazole, all of which can be unsubstituted, mono- or polysubstituted with L as defined above.

Especially preferred substituents R, R ^s and R ^1"17 in the above formulae and subformulae are selected from straight chain, branched or cyclic alkyl having from 1 to 20 C atoms, which is unsubstituted or mono- or polysubstituted by F, CI, Br or I, and wherein one or more non-adjacent CH ₂ groups are optionally replaced, in each case independently from one another, by .0-, -S-, -NR ^b -, -SiR ^b R ^c -, -CX ¹ =CX ² - or -C≡C- in such a manner that O and/or S atoms are not linked directly to one another, or denotes optionally substituted aryl or heteroaryl preferably having from 1 to 30 C-atoms, with R ^b and R ^c being independently of each other H or alkyl having from 1 to 12 C-atoms, and X ¹ and X ² being independently of each other H, F, CI or CN.

R ^15"17 and R" are preferably identical or different groups selected from a Cr C ₄₀ -alkyl group, preferably C C ₄ -alkyl, most preferably methyl, ethyl, n- propyl or isopropyl, a C6-C o-aryl group, preferably phenyl, a C ₆ -C ₄ o- arylalkyl group, a C-i-C ₀ -alkoxy group, or a C ₆ -C ₄₀ -arylalkyloxy group, wherein all these groups are optionally substituted for example with one or more halogen atoms. Preferably, R ^15"17 and R" are each independently selected from optionally substituted

most preferably Ci _-3 -alkyl, for example isopropyl, and optionally substituted C6-io-aryl, preferably phenyl. Further preferred is a silyl group of formula - SiR ¹⁵ R ¹⁶ wherein R ¹⁵ is as defined above and R ¹⁶ forms a cyclic silyl alkyl group together with the Si atom, preferably having 1 to 8 C atoms.

In one preferred embodiment all of R ^15"17 , or all of R", are identical groups, for example identical, optionally substituted, alkyl groups, as in

triisopropylsilyl. Very preferably all of R ^15"17 , or all of R", are identical, optionally substituted Ci-io, more preferably C^, most preferably Ci _-3 alkyl groups. A preferred alkyl group in this case is isopropyl.

Preferred groups -SiR ¹⁵ R ¹⁶ R ¹⁷ and SiR" ₃ include, without limitation, trimethylsilyl, triethylsilyl, tripropylsilyl, dimethylethylsilyl, diethylmethylsilyl, dimethylpropylsilyl, dimethylisopropylsilyl, dipropylmethylsilyl,

diisopropylmethylsilyl, dipropylethylsilyl, diisopropylethylsilyl,

diethylisopropylsilyl, triisopropylsilyl, trimethoxysilyl, triethoxysilyl, triphenylsilyl, diphenylisopropylsilyl, diisopropylphenylsilyl,

diphenylethylsilyl, diethylphenylsilyl, diphenylmethylsilyl, triphenoxysilyl, dimethylmethoxysilyl, dimethylphenoxysilyl, methylmethoxyphenylsilyl, etc., wherein the alkyl, aryl or alkoxy group is optionally substituted.

According to a preferred embodiment of the present invention the OSC material is an organic light emitting material and/or charge transporting material. The organic light emitting materials and charge transporting materials can be selected from standard materials known to the skilled person and described in the literature. Organic light emitting material according to the present application means a material which emits light having a Amax in the range from 400 to 700 nm. Suitable phosphorescent compounds are, in particular, compounds which emit light, preferably in the visible region, on suitable excitation and in addition contain at least one atom having an atomic number greater than 20, preferably greater than 38 and less than 84, more preferably greater than 56 and less than 80. The phosphorescence emitters used are preferably compounds which contain copper, molybdenum, tungsten, rhenium, ruthenium, osmium, rhodium, iridium, palladium, platinum, silver, gold or europium, in particular compounds which contain iridium or platinum. Particularly preferred organic phosphorescent compounds are compounds of formulae (1) to (4):

formula (1) formula (2)

formula (3) ^formula ( ⁴ )

where

DCy is, identically or differently on each occurrence, a cyclic group which contains at least one donor atom, preferably nitrogen, carbon in the form of a carbene or phosphorus, via which the cyclic group is bonded to the metal, and which may in turn carry one or more substituents R ¹⁸ ; the groups DCy and CCy are connected to one another via a covalent bond;

CCy is, identically or differently on each occurrence, a cyclic group which contains a carbon atom via which the cyclic group is bonded to the metal and which may in turn carry one or more substituents R ⁸ ; A is, identically or differently on each occurrence, a monoanionic, bidentate chelating ligand, preferably a diketonate ligand;

R ¹⁸ are identically or differently at each instance, and are F, CI, Br, I, N0 ₂ , CN, a straight-chain, branched or cyclic alkyl or alkoxy group having from 1 to 20 carbon atoms, in which one or more nonadjacent CH2 groups may be replaced by -0-, -S-, -NR ¹⁹ -, -CONR ¹⁹ -, -CO-0-, -C=0-, -CH=CH- or -C≡C-, and in which one or more hydrogen atoms may be replaced by F, or an aryl or heteroaryl group which has from 4 to 14 carbon atoms and may be substituted by one or more

nonaromatic R ¹⁸ radicals, and a plurality of substituents R ⁸ , either on the same ring or on two different rings, may together in turn form a mono- or polycyclic, aliphatic or aromatic ring system; and

R ¹⁹ are identically or differently at each instance, and are a straight-chain, branched or cyclic alkyl or alkoxy group having from 1 to 20 carbon atoms, in which one or more nonadjacent CH ₂ groups may be replaced by -0-, -S-, -CO-O-, -C=0-, -CH=CH- or -C≡C-, and in which one or more hydrogen atoms may be replaced by F, or an aryl or heteroaryl group which has from 4 to 14 carbon atoms and may be substituted by one or more nonaromatic R ¹⁸ radicals.

Formation of ring systems between a plurality of radicals R ¹⁸ means that a bridge may also be present between the groups DCy and CCy.

Furthermore, formation of ring systems between a plurality of radicals R ¹⁸ means that a bridge may also be present between two or three ligands CCy-DCy or between one or two ligands CCy-DCy and the ligand A, giving a polydentate or polypodal ligand system.

Preferably, the semiconducting compounds according to formulae (1), (2), (3) and (4) meets the requirements of formula (I), formula (II) and/or formula (III) and comprise a solubilizing structure element of formulae (L-l), (L-ll) and (L-lll), respectively.

Examples of the emitters described above are revealed by the applications WO 00/70655, WO 01/41512, WO 02/02714, WO 02/15645, EP 1191613, EP 1191612, EP 1191614, WO 04/081017, WO 05/033244,

WO 05/042550, WO 05/1 13563, WO 06/008069, WO 06/061182,

WO 06/081973 and DE 102008027005. In general, all phosphorescent complexes as are 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 compounds without inventive step. In particular, it is known to the person skilled in the art which phosphorescent complexes emit with which emission colour.

Examples of preferred phosphorescent compounds are shown in the following table.

30

30

Preferred dopants are selected from the class of the monostyrylamines, the distyrylamines, the tristyrylamines, the tetrastyrylamines, the styryl- phosphines, 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. Corresponding phosphines and ethers are defined analogously to the amines. For the purposes of the present 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, particularly preferably having at least 14 aromatic ring atoms. Preferred examples thereof are aromatic anthraceneamines, aromatic anthracenediamines, aromatic pyreneamines, aromatic pyrenediamines, aromatic chryseneamines or aromatic chrysenediamines. An aromatic anthraceneamine 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 anthracenediamine 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 pyreneamines, pyrenediamines, chryseneamines and chrysenediamines are defined analogously thereto, where the diarylamino groups are preferably bonded to the pyrene in the -position or in the ,6-position. Further preferred dopants are selected from indenofluoreneamines or indenofluorenediamines, for example in accordance with WO 06/122630, benzoindenofluoreneamines or benzo- indenofluorenediamines, for example in accordance with WO 08/006449, and dibenzoindenofluoreneamines or dibenzoindenofluorenediamines, for example in accordance with WO 07/140847. Examples of dopants from the class of the styrylamines are substituted or unsubstituted tristilbeneamines or the dopants described in WO 06/000388, WO 06/058737,

WO 06/000389, WO 07/065549 and WO 07/1 156 0. Preference is furthermore given to the condensed hydrocarbons disclosed in

DE 102008035413.

Suitable dopants are furthermore the structures depicted in the following table, and the derivatives of these structures disclosed in JP 06/001973, WO 04/047499, WO 06/098080, WO 07/065678, US 2005/0260442 and WO 04/092111.

The proportion of the dopant in the mixture of the emitting layer is between 0.1 and 50.0 % by weight, preferably between 0.5 and 20.0 % by weight, particularly preferably between 1.0 and 10.0 % by weight. Correspondingly, the proportion of the host material is between 50.0 and 99.9 % by weight, preferably between 80.0 and 99.5 % by v, particularly preferably between 90.0 and 99.0 % by weight. Suitable host materials for this purpose are materials from various classes of substance. Preferred host materials are selected from the classes of the oligoarylenes (for example 2,2',7,7'-tetraphenylspirobifluorene in

accordance with EP 676461 or dinaphthylanthracene), in particular the oligoarylenes containing condensed aromatic groups, the oligoarylene- vinylenes (for example DPVBi or spiro-DPVBi in accordance with

EP 676461), the polypodal metal complexes (for example in accordance with WO 04/081017), the hole-conducting compounds (for example in accordance with WO 04/058911), the electron-conducting compounds, in particular ketones, phosphine oxides, sulfoxides, etc. (for example in accordance with WO 05/084081 and WO 05/084082), the atropisomers (for example in accordance with WO 06/048268), the boronic acid derivatives (for example in accordance with WO 06/1 7052) or the benzanthracenes (for example in accordance with WO 08/145239). Suitable host materials are furthermore also the benzo[c]phenanthrene compounds according to the invention which are described above. Apart from the compounds according to the invention, 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 oligoarylenevinylenes, the ketones, the phosphine oxides and the sulfoxides. Apart from the benzo[c]phenanthrene compounds according to the invention, 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 this invention, 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.

Suitable host materials are furthermore, for example, the materials depicted in the following table, and derivatives of these materials, as disclosed in WO 04/018587, WO 08/006449, US 5935721 , US 2005/0 81232,

JP 2000/273056, EP 681019, US 2004/0247937 and US 2005/02 1958.

For the purposes of this invention, a hole-injection layer is a layer which is directly adjacent to the anode. For the purposes of this invention, a hole- transport layer is a layer which is located between a hole-injection layer and an emission layer. It may be preferred for them to be doped with electron- acceptor compounds, for example with F ₄ -TCNQ or with compounds as described in EP 1476881 or EP 1596445.

Suitable charge-transport materials, as can be used in the hole-injection or hole-transport layer or in the electron-injection or electron-transport layer of the organic electroluminescent device according to the invention, are, for example, the compounds disclosed in Y. Shirota et al., Chem. Rev. 2007, 107(4), 953-1010, or other materials as employed in these layers in accordance with the prior art. Examples of preferred hole-transport materials which can be used in a hole-transport or hole-injection layer of the electroluminescent device according to the invention are indenofluoreneamines and derivatives (for example in accordance with WO 06/122630 or WO 06/100896), the amine derivatives as disclosed in EP 1661888, hexaazatriphenylene derivatives (for example in accordance with WO 01/049806), amine derivatives with condensed aromatics (for example in accordance with US 5,061 ,569), the amine derivatives as disclosed in WO 95/09147, monobenzoindenofluoren- eamines (for example in accordance with WO 08/006449) or dibenzo- indenofluoreneamines (for example in accordance with WO 07/140847). Suitable hole-transport and hole-injection materials are furthermore derivatives of the compounds depicted above, as disclosed in JP

2001/226331 , EP 676461 , EP 650955, WO 01/049806, US 4780536, WO 98/30071 , EP 891121 , EP 1661888, JP 2006/253445, EP 650955, WO 06/073054 and US 5061569.

Suitable hole-transport or hole-injection materials are furthermore, for example, the materials indicated in the following table.

Suitable electron-transport or electron-injection materials which can be used in the electroluminescent device according to the invention are, for example, the materials indicated in the following table. Suitable electron- transport and electron-injection materials are furthermore derivatives of the compounds depicted above, as disclosed in JP 2000/053957,

WO 03/060956, WO 04/028217 and WO 04/080975.

Suitable matrix materials for the compounds according to the invention are ketones, phosphine oxides, sulfoxides and sulfones, for example in accordance with WO 04/013080, WO 04/093207, WO 06/005627 or DE 102008033943, triarylamines, carbazole derivatives, for example CBP

(Ν,Ν-biscarbazolyl-biphenyl) or the carbazole derivatives disclosed in WO 05/039246, US 2005/0069729, JP 2004/288381 , EP 1205527 or WO 08/086851 , indolocarbazole derivatives, for example in accordance with WO 07/063754 or WO 08/056746, azacarbazoles, for example in accordance with EP 1617710, EP 1617711 , EP 1731584, JP 2005/347160, bipolar matrix materials, for example in accordance with WO 07/137725, silanes, for example in accordance with WO 05/111172, azaboroles or boronic esters, for example in accordance with WO 06/117052, triazine derivatives, for example in accordance with DE 102008036982,

WO 07/063754 or WO 08/056746, or zinc complexes, for example in accordance with DE 102007053771.

The organic semiconducting compound of the present invention preferably has a molecular weight of 5000 g/mol or less, especially a molecular weight of 2000 g/mol or less.

According to a special aspect of the present invention, the organic semiconducting compound may preferably have a molecular weight of at least 550 g/mol, especially at least 800 g/mol, particularly at least 900 g/mol and more preferably at least 950 g/mol. Astonishing improvements can be achieved with one or more functional compounds having a high solubility. Preferred organic functional compounds can comprise Hansen Solubility parameters of H _d in the range of 17.0 to 20.0 MPa ^{0 5} , H _p in the range of 2 to 10.0 MPa ^{0 5} and H _h in the range of 0.0 to 5.0 MPa ^{0 5} . More preferred functional compounds comprise Hansen Solubility parameters of H _d in the range of 17.5 to 19.0 MPa ^{0 5} , H _p in the range of 3.5 to 8.0 MPa ^{0 5} and H _h in the range of 3.0 to 10.0 MPa ^{0 5} .

Surprising effects can be achieved with functional compounds having a radius of at least 3.0 MPa ^{0 5} , preferably at least 4.5 MPa ^{0 5} and more preferably at least 5.0 MPa ⁰ ^determined according to Hansen Solubility parameters.

Especially preferred host materials, hole-transport materials, electron- or exciton-blocking materials, matrix materials for fluorescent or

phosphorescent compounds, hole-blocking materials or electron-transport materials comprise one or more compounds according to formula (H1 )

formula (H1) where the following applies to the symbols used:

Y is C=0 or C(R ² ) ₂ ;

X is on each occurrence, identically or differently, CR ²² or N;

R ²⁰ is on each occurrence, identically or differently, an aromatic or hetero- aromatic ring system having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R , or an N(Ar)2, Si(Ar)3, C(=0)Ar, OAr, ArSO, ArS0 ₂ , P(Ar) ₂ , P(0)(Ar) ₂ or B(Ar) ₂ group; is on each occurrence, identically or differently, an aromatic or hetero- aromatic ring system having 5 to 30 aromatic ring atoms, which may be substituted by one or more non-aromatic radicals R ²³ ; two radicals Ar here which are bonded to the same nitrogen, phosphorus or boron atom may also be linked to one another by a single bond or a bridge selected from B(R ²⁴ ), C(R ² ) ₂₎ Si(R ²⁴ ) ₂ , C=0, C=N R ²⁴ , C=C(R ²⁴ ) ₂ , O, S, S=0, S0 ₂ , N(R ²⁴ ), P(R ²⁴ ) and P(=0) R ²⁴ ;

is on each occurrence, identically or differently, H, D, F or a linear alkyl group having 1 to 20 C atoms or a branched or cyclic alkyl group having 3 to 20 C atoms; a plurality of radicals R ²¹ here may form a ring system with one another;

is on each occurrence, identically or differently, H, D, F, CN, a straight-chain alkyl, alkoxy or thioalkoxy group having 1 to 40 C atoms or a branched or cyclic alkyl, alkoxy or thioalkoxy group having 3 to 40 C atoms, each of which may be substituted by one or more radicals R ²⁴ , where one or more non-adjacent CH ₂ groups may be replaced by R ²⁴ C=C R ²⁴ , C≡C, O or S and where one or more H atoms may be replaced by F;

is on each occurrence, identically or differently, H, D, F, CI, Br, I, CHO, N(Ar) ₂ , C(=0)Ar, P(=0)(Ar) ₂ , S(=0)Ar, S(=0) ₂ Ar, CR ²² =CR ²² Ar, CN, N0 ₂ , Si(R ²⁴ ) ₃ , B(0 R ² ) ₂ , B(R ² ) ₂ , B(N(R ² ) ₂ ) ₂ , OS0 ₂ R ²⁴ , a straight- chain alkyl, alkoxy or thioalkoxy group having 1 to 40 C atoms or a branched or cyclic alkyl, alkoxy or thioalkoxy group having 3 to 40 C atoms, each of which may be substituted by one or more radicals R ²⁴ , where one or more non-adjacent CH ₂ groups may be replaced by R C=C R ²⁴ , C≡C, Si(R ²⁴ ) ₂ , Ge(R ²⁴ ) ₂ , Sn(R ² ) ₂ , C=0, C=S, C=Se, C=N R ²⁴ , P(=0)( R ²⁴ ), SO, S0 ₂ , R ²⁴ , O, S or CON R ²⁴ and where one or more H atoms may be replaced by F, CI, Br, I, CN or N0 ₂ , or an aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms, which may in each case be substituted by one or more radicals R ²⁴ , or an aryloxy or heteroaryloxy group having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R ²⁴ , or a combination of these systems; two or more adjacent substituents R here may also form a mono- or polycyclic, aliphatic or aromatic ring system with one another;

is on each occurrence, identically or differently, H, D or an aliphatic, aromatic and/or heteroaromatic hydrocarbon radical having 1 to 20 C atoms, in which, in addition, H atoms may be replaced by F; two or more adjacent substituents R ²⁴ here may also form a mono- or polycyclic, aliphatic or aromatic ring system with one another.

More preferably, compounds according to according to formula (H1a) be used

wherein the residue R has the same meaning as in formula (H1)

More preferably, compounds according to according to formula (Mb) can be used

wherein the residue R has the same meaning as in formula (M)

Preferably, the compounds according to formulae (H1), (H1a) and/or (Mb), meet the requirements of formula (I), formula (II) and/or formula (III) and comprise a solubilizing structure element of formulae (L-l), (L-ll) and (L-lll), respectively. Especially preferred host materials, hole-transport materials, electron- or exciton-blocking materials, matrix materials for fluorescent or phosphorescent compounds, hole-blocking materials or electron-transport materials comprise one or more compounds according to formula (H2a) and/or (H2b)

where the following applies to the symbols used:

Y* is C if a group X ² is bonded to the group Y, or is on each occurrence, identically or differently, CR ²⁵ or N if no group X ² is bonded to the group Y;

E is on each occurrence, identically or differently, a covalent single bond or a divalent bridge selected from N(R ²⁶ ), B(R ²⁶ ), C(R ²⁶ ) _2l O, Si(R ²⁶ ) ₂ , C=N R ²⁶ , C=C(R ²⁶ ) ₂ , S, S=0, S0 ₂ , P(R ²⁶ ) and P(=0) R ²⁶ ;

X ¹ is on each occurrence, identically or differently, a divalent bridge

selected from N(R ²⁶ ), B(R ²⁶ ), O, C(R ²⁶ ) ₂ , Si(R ²⁶ ) ₂ , C=N R ²⁶ ,

C=C(R ²⁶ ) ₂ , S, S=0, S0 ₂ , P(R ²⁶ ) and P(=0) R ²⁶ ;

X ² is on each occurrence, identically or differently, a divalent bridge

selected from N(R ²⁶ ), B(R ²⁶ ), C(R ²⁶ ) ₂ , Si(R ²⁶ ) ₂ , C=0, C=N R ²⁶ , C=C(R ⁶ ) ₂ , S, S=0, S0 ₂ , C R ²⁶ -C R ²⁶ , P(R ²⁶ ) and P(=0) R ²⁶ ;

X ³ is on each occurrence, identically or differently, a divalent bridge

selected from N, B, C(R ²⁶ ), Si(R ²⁶ ), P and P(=0); L is a divalent aromatic or heteroaromatic ring system having 5 to 40 aromatic ring atoms, which may be substituted by one or more radicals R ²⁶ ;

n, m are, identically or differently on each occurrence, 0 or 1 , with the

proviso that n + m = 1 or 2;

q is 1 , 2, 3, 4, 5 or 6;

R ²⁵ is on each occurrence, identically or differently, H, D, F, CI, Br, I,

N(Ar) ₂ , C(=0) Ar ⁴ , P(=0) Ar ⁴ ₂ , S(=0) Ar ⁴ , S(=0) ₂ Ar ⁴ , CR ²⁷ =C R ²⁷ Ar ⁴ , CN, N0 ₂ , Si(R ²⁷ ) ₃ , B(0 R ²⁷ ) ₂ , OS0 ₂ R ²⁷ , a straight-chain alkyl, alkoxy or thioalkoxy group having 1 to 40 C atoms or a branched or cyclic alkyl, alkoxy or thioalkoxy group having 3 to 40 C atoms, each of which may be substituted by one or more radicals R ²⁷ , where one or more non-adjacent CH ₂ groups may be replaced by R ²⁷ C=C R ²⁷ , C=C, Si(R ²⁷ ) ₂ , Ge(R ²⁷ ) _2> Sn(R ²⁷ ) ₂ , C=0, C=S, C=Se, C=N R ²⁷ , P(=0)( R ²⁷ ), SO, S0 ₂ , N R ²⁷ , O, S or CON R ²⁷ and where one or more H atoms may be replaced by D, F, CI, Br, I, CN or N0 ₂ , or an aryl or heteroaryl group having 5 to 40 ring atoms, which may in each case be substituted by one or more radicals R ²⁷ , or an aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms, which may in each case be substituted by one or more radicals R ²⁷ , or an aryloxy or heteroaryloxy group having 5 to 40 aromatic ring atoms, which may be substituted by one or more radicals R ²⁷ , or an aralkyl or heteroaralkyl group having 5 to 40 aromatic ring atoms, which may be substituted by one or more radicals R ²⁷ , or a combination of these systems; two or more substituents R here, together with the atoms to which they are bonded, may also form a mono- or polycyclic aliphatic or aromatic ring system with one another or, if they are bonded to Ar ⁴ , with Ar ⁴ ;

R ²⁶ is on each occurrence, identically or differently, H, D, F, CI, Br, I, CN, N0 ₂ , CF ₃ , B(OR ²⁷ ) ₂ , Si(R ²⁷ ) ₃ , a straight-chain alkyl, alkoxy or thioalkoxy group having 1 to 40 C atoms or a branched or cyclic alkyl, alkoxy or thioalkoxy group having 3 to 40 C atoms, or an alkenyl or alkynyl group having 2 to 40 C atoms, each of which may be substituted by one or more radicals R , where one or more non- adjacent CH ₂ groups may be replaced by -R ²⁷ C=CR ²⁷ -, -C≡C-, Si(R ²⁷ ) ₂ , Ge(R ²⁷ ) ₂ , Sn(R ²⁷ ) _2> C=0, C=S, C=Se, C=N R ²⁷ , -0-, -S-, -COO- or -CON R ²⁷ - and where one or more H atoms may be replaced by F, CI, Br, I, CN or N0 ₂ , or arylamines, or substituted or unsubstituted carbazoles, which may in each case be substituted by one or more radicals R ²⁷ , or an aryl or heteroaryl group having 5 to 40 ring atoms, which may be substituted by one or more aromatic, heteroaromatic or non-aromatic radicals R ²⁷ , or an aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms, which may be substituted by one or more non-aromatic radicals R ²⁷ , or an aryloxy or heteroaryloxy group having 5 to 40 aromatic ring atoms, which may be substituted by one or more radicals R ²⁷ , or an aralkyl or heteroaralkyl group having 5 to 40 aromatic ring atoms, which may be substituted by one or more radicals R ²⁷ , or a combination of these systems; two or more substituents R ²⁶ here may also form a mono- or polycyclic aliphatic or aromatic ring system with one another, together with the atoms to which they are bonded;

R ²⁷ is on each occurrence, identically or differently, H, D or an aliphatic hydrocarbon radical having 1 to 20 C atoms or an aryl or heteroaryl group having 5 to 40 ring atoms, or a combination of these groups;

Ar ⁴ is on each occurrence, identically or differently, an aromatic or

heteroaromatic ring system, preferably an aryl or heteroaryl group having 5 to 40 ring atoms, which may be substituted by one or more radicals R ²⁶ .

Preferably, the compounds according to formulae (H2a) and/or (H2b), meet the requirements of formula (I), formula (II) and/or formula (III) and comprise a solubilizing structure element of formulae (L-l), (L-ll) and (L-lll), respectively. Especially preferred host materials, hole-transport materials, electron- or exciton-blocking materials, matrix materials for fluorescent or

phosphorescent compounds, hole-blocking materials or electron-transport materials comprise one or more compounds according to formula (H3a) and/or formula (H3b)

formula (H 3a) and/or

formula (H3b)

where the following applies to the symbols and indices used: Ar ⁵ is a group of the following formula (H3c):

formula (H3c) where the dashed bond indicates the bond to the spirobifiuorene; Ar ⁶ is a group of the following formula (H3d):

formula (H3d) where the dashed bonds indicate the bonds to the spirobifiuorene;

R ²⁸ , R are on each occurrence, identically or differently, H, D, F, CI, Br, I,

CHO, N(R ³⁰ ) ₂ , N(Ar ⁷ ) ₂ , B(Ar ⁷ ) _2> C(=0)Ar ⁷ , P(=0)(Ar ⁷ ) ₂ , S(=0)Ar ⁷ , S(=0) ₂ Ar ⁷ , CR ³⁰ =CR ³⁰ Ar ⁷ _> CN, N0 ₂ , Si(R ³⁰ ) ₃ , B(OR ³⁰ ) _2> B(R ³⁰ ) _2> B(N(R ³⁰ ) ₂ )2, OS0 ₂ R ³⁰ , a straight-chain alkyl, alkenyl, alkynyl, alkoxy or thioalkoxy group having 1 to 40 C atoms or a branched or cyclic alkyl, alkenyl, alkynyl, alkoxy or thioalkoxy group having 3 to 40 C atoms, each of which may be substituted by one or more radicals R ³⁰ , where one or more non-adjacent CH ₂ groups may be replaced by R ³⁰ C=CR ³⁰ , C≡C, Si(R ³⁰ ) ₂ , Ge(R ³⁰ ) ₂ , Sn(R ³⁰ ) _2l C=0, C=S, C=Se, C=NR ³⁰ , P(=0)(R ³⁰ ), SO, S0 ₂ , NR ³⁰ , O, S or CONR ³⁰ and where one or more H atoms may be replaced by D, F, CI, Br, I, CN or N0 ₂ , or an aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms, which may in each case be substituted by one or more radicals R , or an aryloxy or heteroaryloxy group having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R ³⁰ , or a combination of these systems; two or more adjacent substituents R ²⁸ here may also form a mono- or polycyclic, aliphatic or aromatic ring system with one another;

is on each occurrence, identically or differently, an aromatic or heteroaromatic ring system having 5 to 30 aromatic ring atoms, which may be substituted by one or more radicals R ³⁰ ; two radicals Ar ⁷ here which are bonded to the same nitrogen, phosphorus or boron atom may also be linked to one another by a single bond or a bridge selected from B(R ³⁰ ), C(R ³⁰ ) ₂ , Si(R ³⁰ ) ₂ , C=0, C=NR ³⁰ , C=C(R ³⁰ ) ₂ , O, S, S=0, S0 ₂ , N(R ³⁰ ), P(R ³⁰ ) and P(=0)R ³⁰ ;

is on each occurrence, identically or differently, H, D or an aliphatic, aromatic and/or heteroaromatic hydrocarbon radical having 1 to 20 C atoms, in which, in addition, H atoms may be replaced by D or F; two or more adjacent substituents R ³⁰ here may also form a mono- or polycyclic, aliphatic or aromatic ring system with one another;

is 0 or 1 ;

is 0, 1 , 2 or 3;

is 0, 1 , 2, 3 or 4 if n = 0 in the same ring and is 0, 1 , 2 or 3 if n = 1 in the same ring.

Preferably, the compounds according to formulae (H3a) and/or (H3b), meet the requirements of formula (I), formula (II) and/or formula (III) and comprise a solubilizing structure element of formulae (L-l), (L-ll) and (L-lll), respectively. Preferred compounds having solubilising groups being useful for performing the present invention include

30

Further suitable compounds, their Hansen Solubility Parameters incl. their radiuses are mentioned in the following table:

30

According to a preferred embodiment, the organic semiconducting compounds (OSC) preferably have a molecular weight of at most 5000 g/mol, particularly at most 2000 g/mol, especially at most 1500 g/mol and more preferably at most 1000 g/mol. According to a special embodiment of the present invention, the formulation can comprise 0.1 to 10 % by weight, preferably 0.25 to 5 % more preferably 0.5 to 4 % by weight organic semiconducting compounds, preferably emitting materials and/or charge transporting materials.

The composition of the present invention comprises at least one solvent selected from dimethyl anisole. These compounds include 2,3-, 2,4-, 2,5-, 2,6-, 3,4- and 3,5- isomers of dimethylanisole. Preferably, the solvent includes 2,5-dimethylanisole, 2,6-dimethylanisole, 3,4-dimethylanisole, 3,5- dimethylanisole or a mixture of these solvents. The most preferred solvent is 3,4-dimethylanisole.

In addition thereto, the composition may comprise a further solvent. By using an additional solvent an astonishing improvement in solubility can be obtained, obtaining the correct balance of evaporation rate and boiling point is essential in order to maintain solubility whilst drying. Preferably, 1 ,2,4,5 tetra methyl benzene can be used as additional solvent.

Preferred organic solvents can comprise Hansen Solubility parameters of H _d in the range of 16.0 to 23.2 MPa ⁰⁵ , H _p in the range of 0.0 to 12.5 MPa ^{0 5} and H _h in the range of 0.0 to 14.2 MPa ^{0 5} . More preferred organic solvents comprise Hansen Solubility parameters of H _d in the range of 17.0 to 20.0 MPa ^{0 5} , H _p in the range of 2.0 to 8.0 MPa ^{0 5} and H _h in the range of 2.0 to 9.0 MPa ⁰⁵ .

Preferably the solvent has a boiling point or sublimation temperature of < 400°C, especially < 300°C, more preferably < 250°C, most preferably < 200°C, at the pressure employed, very preferably at atmospheric pressure (1013 hPa). Evaporation can also be accelerated e.g. by applying heat and/or reduced pressure. Unexpected improvements can be achieved by using solvents having a boiling point of at least 00°C, preferably at least 130°C. Usually, the organic solvent can comprise a surface tension in the range of 15 to 80 mN/m, especially in the range of 20 to 60 mN/m and preferably in the range of 25 to 40 mN/m. The surface tension can be measured using a FTA (First Ten Angstrom) 1000 contact angle goniometer at 25°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.

For the purpose for making a rough estimate, the surface tension can be calculated using the Hansen Solubility Parameters by the formula expound- ded in Hansen Solubility Parameters: A User's Handbook, Second Edition, C. M. Hansen (2007), Taylor and Francis Group, LLC (HSPiP manual).

Surface tension = 0.0146 x(2.28x^ H _d ² +^ H _P ² +^ H _h ² ) x MVol ⁰² , where:

H _d refers to Dispersion contribution

H _p refers to Polar contribution

H _h refers to Hydrogen bonding contribution

MVol refers to Molar Volume.

The Hansen Solubility Parameters can be determined according to the Hansen Solubility Parameters in Practice HSPiP 3 ^rd edition, (Software version 3.0.38) with reference to the Hansen Solubility Parameters: A User's Handbook, Second Edition, C. M. Hansen (2007), Taylor and Francis Group, LLC) as supplied by Hanson and Abbot et al.

Preferably, the solvent or the solvent blend has a viscosity in the range of 1.0 to 100 mPas, especially 1.2 to 10 mPas, more preferably in the range of 1.3 to 10 mPas and most preferably in the range of 1.4 to 8 mPas. The viscosity is determined at a temperature of 25°C by measuring on AR-G2 rheometer manufactured by TA Instruments. This measurement can be done over a shear range of 10 to 1000 s ^"1 using 40 mm parallel plate geometry. Preferably, the solvent can comprise a relative evaporation rate (Butyl acetate = 00) of at least 0.01 , particularly of at least 0.1, especially of at least 0.5, preferably of at least 1 , and most preferably of at least 2. The relative evaporation rate can be determined according to DIN 53170:2009- 08. For the purpose for making a rough estimate, the relative evaporation rate can be calculated using the Hansen Solubility Parameters with the HSPiP program as mentioned above and below.

Preferably, the solvent useful for the present invention may comprise at least 40 % by weight, especially at least 60 % by weight and more preferably at least 75 % by weight dimethylanisole, especially 2,5- dimethylanisole, 2,6-dimethylanisole, 3,4-dimethylanisole, 3,5-dimethyl- anisole or a mixture of these solvents, more preferably 3,4-dimethylanisole.

Preferably, the inert binder increases the solvent viscosity of at least 0.4 cps when dissolving 1 % w/w of the inert binder in said organic solvent.

The composition of the present invention can particularly comprise at least 70 % by weight, especially at least 80 % by weight and preferably at least 90 % by weight of organic solvents.

Preferably, the composition of the present invention may comprise at least 40 % by weight, especially at least 60 % by weight and more preferably at least 75 % by weight dimethylanisole, especially 2,5-dimethylanisole, 2,6- dimethylanisole, 3,4-dimethylanisole, 3,5-dimethylanisole or a mixture of these solvents, more preferably 3,4-dimethylanisole. According to a very preferred embodiment of the present invention, the solvent consists of 3,4-dimethylanisole.

Preferably, the composition has a viscosity in the range of 1.0 to 100 mPas, especially 1.2 to 40 mPas, more preferably in the range of 1.4 to 20 mPas and most preferably in the range of 1.5 to 15 mPas. The viscosity is determined at a temperature of 25°C by measuring on AR-G2 rheometer manufactured by TA Instruments. This is measured using a parallel plate geometry as mentioned above.

Preference is furthermore also given to solutions of non-conducting, electronically inert polymers (matrix polymers; inert polymeric binders) which comprise admixed low-molecular-weight, oligomeric, dendritic, linear or branched and/or polymeric organic and/or organometallic semiconductors. Preferably, the formulation may comprise 0.1 to 10 % more preferably 0.25 to 5% most preferably 0.3 to 3% by weight inert polymeric binders.

Optionally, the OSC formulation comprises one or more organic binders, pre-ferably polymeric binders to adjust the rheological properties, as described for example in WO 2005/055248 A1 , in particular an organic binder which has a low permittivity (ε) at 1 ,000 Hz of 3.3 or less, very preferably in a proportion of binder to OSC compounds from 20:1 to 1 :20, preferably 10:1 to 1 :10, especially 5:1 to 1:5, more preferably 1 :1 to 1 :5 by weight.

Preferably, the polymeric binder comprises a weight average molecular weight in the range of 1000 to 15,000,000 g/mol, especially 1500 to

12,000,000 g/mol, and most especially 1500 to 10,000,000 g/mol.

Surprising effects can be achieved with polymers having a weight average molecular weight of at least 10,000 g/mol, preferably at least 200,000 g/mol, especially at least 300,000 g/mol and more preferably at least 500,000 g/mol. According to a very preferred aspect of the present invention, the polymers can preferably have a weight average molecular weight of at least 1 ,000,000 g/mol and more preferably at least 2,000,000 g/mol.

The polymers being useful as inert binders can preferably have a weight average molecular weight of at most 20,000,000 g/mol, more preferably of at most 12,000,000 g/mol and most preferably at most 7,000,000 g/mol. In particular, the polymer can have a polydispersity index M _w /M _n in the range of 1.0 to 10.0, more preferably in the range of 1.0 to 5.0 and most preferably in the range of 1.0 to 3. Astonishing improvements can be achieved with preferable polymers having a polydispersity index Mw/M _n in the range of 1.0 to 2.0, especially 1.0 to 1.5 and more preferably 1.0 to 1.2.

According to a special aspect of the present invention, the polymeric binder may have a multi modal molecular weight distribution. Preferably, the polymer may have 2, 3, 4 or more maxima in the molecular weight distribution as determinable using GPC.

The binder is selected for example from polystyrene, poly( -methylstyrene), polyvinylcinnamate, poly(4-vinylbiphenyl) or poly(4-methylstyrene).

Polymeric binders preferably comprise repeating units derived from styrene and/or olefins. Preferred polymeric binders can comprise at least 80 %, especially 90 % and more preferably 99 % by weight of repeating units derived from styrene monomers and/or olefins.

The binder may also be a semiconducting binder selected for example from poly-arylamines, polyfluorenes, polythiophenes, polyspirobifluorenes, substituted polyvinylenephenylenes, polycarbazoles or polystilbenes, or copolymers thereof. According to a preferred embodiment of the present invention, an inert binder is a polymer having a glass transition temperature in the range of -70 to 160°C, more preferably, 0 to 150°C, especially 50 to 140°C and most preferably 70 to 130°C. The glass transition temperature can be determined by measuring the DSC of the polymer (DIN EN ISO 11357, heating rate 10°C per minute).

Usually, the polymeric binder is dispersible or soluble in the solvent of the present formulation as described above and below. Preferably, the polymeric binder is soluble in the organic solvent and the solubility of the polymeric binder in the solvent is at least 1 g/l, especially at least 5 g/l and more preferably at least 10 g/l.

According to a special embodiment of the present invention, the

composition of the present invention can comprise 0.05 to 10 % by weight, preferably 0.1 to 5 % more preferably 0.15 to 3 % by weight polymeric binder. Astonishing improvements can be achieved by using formulations preferably comprising 0.2 to 1 %, more preferably 0.25 to 0.6 % and most preferably 0.3 to 0.5 % by weight polymeric binder.

Astonishing improvements can be achieved by using a high molecular weight binder at a low content in the formulation. Using such approach surprisingly efficient devices having an excellent printing quality are obtainable.

The weight ratio of the semiconducting compound to the inert binder is preferably in the range of 30:1 to 1 :30, particularly in the range of 20:1 to 1 :5 and more preferably in the range of 5:1 to 1 :1 , if a binder is used. According to a special embodiment the polymeric binders preferably comprise repeating units derived from styrene and/or olefins. Preferred polymeric binders can comprise at least 80 %, especially 90 % and more preferably 99 % by weight of repeating units derived from styrene monomers and/or olefins.

Styrene monomers are well known in the art. These monomers include styrene, substituted styrenes with an alkyl substituent in the side chain, such as a-methylstyrene and α-ethylstyrene, substituted styrenes with an alkyl substituent on the ring such as vinyltoluene and p-methylstyrene, halogenated styrenes such as monochlorostyrenes, dichlorostyrenes, tribromostyrenes and tetrabromostyrenes.

Olefins are monomers consisting of hydrogen and carbon atoms. These monomers include ethylene, propylene, butylenes, isoprene and 1 ,3- butadiene.

According to a special aspect of the present invention, the polymeric binder is polystyrene having a weight average molecular weight of preferably at least 100,000 g/mol, especially at least 200,000, especially at least 300,000 g/mol and more preferably at least 500,000 g/mol. According to a very preferred aspect of the present invention, the polystyrene can preferably have a weight average molecular weight of at least 1 ,000,000 g/mol and more preferably at least 2,000,000 g/mol.

The polystyrene being useful as inert binders can preferably have a weight average molecular weight of at most 20,000,000 g/mol, more preferably of at most 12,000,000 g/mol and most preferably at most 7,000,000 g/mol.

The formulation according to the present invention may additionally comprise one or more further components like for example surface-active compounds, lubricating agents, conductive additives, 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, nanoparticles or inhibitors. However, these further components should not be oxidising or otherwise capable of chemically reacting with the OSC or have an electrically doping effect on the OSC. Surprising improvements can be achieved with volatile wetting agents. The term "volatile" as used above and below means that the agent can be removed from the organic semiconducting materials by evaporation, after these materials have been deposited onto a substrate of an OE device, under conditions (like temperature and/or reduced pressure) that do not significantly damage these materials or the OE device. Preferably this means that the wetting agent has a boiling point or sublimation temperature of < 350°C, more preferably < 300°C, most preferably < 250°C, at the pressure employed, very preferably at atmospheric pressure (1013 hPa). Evaporation can also be accelerated e.g. by applying heat and/or reduced pressure. Preferably, the wetting agents are not capable of chemically reacting with the OSC compounds. In particular they are selected from compounds that do not have a permanent doping effect on the OSC material (e.g. by oxidising or otherwise chemically reacting with the OSC material). Therefore, the formulation preferably should not contain additives, like e.g. oxidants or protonic or lewis acids, which react with the OSC materials by forming ionic products.

Surprising effects can be accomplished by formulations comprising volatile components having similar boiling points. Preferably, the difference of the boiling point of the wetting agent and the organic solvent is in the range of -50°C to 50°C, more preferably in the range of -30°C to 30°C and most preferably in the range of -20°C to 20°C.

Preferred wetting agents are non-aromatic compounds. With further preference the wetting agents are non-ionic compounds. Particular useful wetting agents comprise a surface tension of at most 35 mN/m, especially of at most 30 mN/m, and more preferably of at most 25 mN/m. The surface tension can be measured using a FTA (First Ten Angstrom) 1000 contact angle goniometer at 25°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.

According to a special aspect of the present invention, the difference of the surface tension of the organic solvent and the wetting agent is preferably at least 1 mN/m, especially at least 5 mN/m and more preferably at least 10 mN/m.

Unexpected improvements can be achieved by wetting agents comprising a molecular weight of at least 100 g/mol, especially at least 150 g/mol, preferably at least 80 g/mol and more preferably at least 200 g/mol.

Suitable and preferred wetting agents that do not oxidise or otherwise chemically react with the OSC materials are selected from the group consisting of siloxanes, alkanes, amines, alkenes, alkynes, alcohols and/or halogenated derivates of these compounds. Furthermore, fluoro ethers, fluoro esters and/or fluoro ketones can be used. More preferably, these compounds are selected from methyl siloxanes having 6 to 20 carbon atoms, especially 8 to 16 carbon atoms; C7-C14 alkanes, C7-C14 alkenes, C7-C14 alkynes, alcohols having 7 to 14 carbon atoms, fluoro ethers having 7 to 14 carbon atoms, fluoro esters having 7 to 14 carbon atoms and fluoro ketones having 7 to 14 carbon atoms. Most preferred wetting agents are methyl siloxanes having 8 to 14 carbon atoms.

Useful and preferred alkanes having 7 to 14 carbon atoms include heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, 3- methyl heptane, 4-ethyl heptane, 5-propyl decane, trimethyl cyclohexane and decalin. Halogenated alkanes having 7 to 14 carbon atoms include 1-chloro heptane, 1 ,2-dichloro octane, tetrafluoro octane, decafluoro dodecane, perfluoro nonane, 1 ,1 ,1-trifluoromethyl decane, and perfluoro methyl decalin.

Useful and preferred alkenes having 7 to 14 carbon atoms include heptene, octene, nonene, 1-decene, 4-decene, undecene, dodecene, tridecene, tetradecene, 3-methyl heptene, 4-ethyl heptene, 5-propyl decene, and trimethyl cyclohexene.

Halogenated alkenes having 7 to 14 carbon atoms include 1 ,2-dichloro octene, tetrafluoro octene, decafluoro dodecene, perfluoro nonene, and 1 , ,1-trifluoromethyl decene.

Useful and preferred alkynes having 7 to 14 carbon atoms include octyne, nonyne, 1-decyne, 4-decyne, dodecyne, tetradecyne, 3-methyl heptyne, 4- ethyl heptyne, 5-propyl decyne, and trimethyl cyclohexyne.

Halogenated alkynes having 7 to 14 carbon atoms include 1 ,2-dichloro octyne, tetrafluoro octyne, decafluoro dodecyne, perfluoro nonyne, and 1 ,1 ,1-trifluoromethyl decyne.

Useful and preferred alcanols having 7 to 14 carbon atoms include, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, 3-methyl heptanol, 3,5-dimethyl-1-hexyn-3-ol, 4-ethyl heptanol, 5-propyl decanol, trimethyl cyclohexanol and hydroxyl decalin.

Halogenated alkanols having 7 to 14 carbon atoms include 1-chloro heptanol, 1 ,2-dichloro octanol, tetrafluoro octanol, decafluoro dodecanol, perfluoro nonanol, 1,1,1-trifluoromethyl decanol, and 2-trifluoro methyl-1- hydroxy decalin. Useful and preferred fluoro ethers having 7 to 14 carbon atoms include 3- ethoxy-1 ,1 ,1 ,2,3,4,4,5,5,6,6,6 dodecafluoro-2-trifluoromethyl-hexane, 3- propoxy-1 , 1 ,1 , 2,3,4,4,5,5,6,6,6 dodecafluoro-2-trifluoromethyl-hexane, and 3-propoxy-1 ,1 , ,2,3,4,4,5,5,5 decafluoro-2-trifluoromethyl-pentane.

Useful and preferred fluoro esters having 7 to 14 carbon atoms include 3-(1 , 1 ,1 , 2,3,4,4,5,5,6,6,6 dodecafluoro-2-trifluoromethyl-hexyl) ethanoate, and 3-(1 ,1 ,1 ,2,3,4,4,5,5,5 decafluoro-2-trifluoromethyl-pentyl) propanoate.

Useful and preferred fluoro ketones having 7 to 14 carbon atoms include 3-(1 , 1 ,1 , 2,3,4,4,5, 5,6, 6,6 dodecafluoro-2-trifluoromethyl-hexyl) ethyl ketone, and 3-(1 , 1 ,1 , 2,3,4,4,5,5,5 decafluoro-2-trifluoromethyl-pentyl) propyl ketone.

Useful and preferred siloxanes include hexamethyl disiloxane, octamethyl trisiloxane, decamethyl tetrasiloxane, dodecamethyl pentasiloxane, and tetradecamethyl hexasiloxane.

Preferably, the formulation may comprise at most 5 % by weight, especially at most 3 % by weight of wetting additives. More preferably, the formulation comprises 0.01 to 4 % by weight, especially preferably 0.1 to 1 % by weight of wetting agent.

The formulation according to the present invention can be designed as an emulsion, dispersion or solution. Preferably, the present formulation is a solution (homogeneous mixture) comprising no considerable amounts of a second phase.

The formulation according to the present invention can be used for the preparation of organic electronic (OE) devices, for example transistors like OFETs or organic photovoltaic (OPV) devices like diodes or solar cells, or organic light emitting diodes (OLED). Especially preferred OE devices are OFETs. A preferred OFET according to the present invention comprises the following components:

- optionally a substrate (1),

- a gate electrode (2),

- an insulator layer comprising a dielectric material (3),

- an OSC layer (4)

- source and drain electrodes (5),

- optionally one or more protection or passivation layers (6).

Figure 1A exemplarily and schematically depicts a typical bottom gate (BG), top contact (TC) OFET device according to the present invention, comprising a substrate (1), a gate electrode (2), a layer of dielectric material (3) (also known as gate insulator layer), an OSC layer (4), and source and drain (S/D) electrodes (5), and an optional passivation or protection layer (6).

The device of Figure 1A can be prepared by a process comprising the steps of depositing a gate electrode (2) on a substrate (1), depositing a dielectric layer (3) on top of the gate electrode (2) and the substrate (1), depositing an OSC layer (4) on top of the dielectric layer (3), depositing S/D electrodes (5) on top of the OSC layer (4), and optionally depositing a passivation or protection layer (6) on top of the S/D electrodes (5) and the OSC layer (4).

Figure 1 B exemplarily and schematically depicts a typical bottom gate (BG), bottom contact (BC) OFET device according to the present invention, comprising a substrate (1), a gate electrode (2), a dielectric layer (3), S/D electrodes (5), an OSC layer (4), and an optional passivation or protection layer (6). The device of Figure 1B can be prepared by a process comprising the steps of depositing a gate electrode (2) on a substrate (1), depositing a dielectric layer (3) on top of the gate electrode (2) and the substrate (1), depositing S/D electrodes (5) on top of the dielectric layer (3), depositing an OSC layer (4) on top of the S/D electrodes (4) and the dielectric layer (3), and optionally depositing a passivation or protection layer (6) on top of the OSC layer (4).

Figure 2 exemplarily and schematically depicts a top gate (TG) OFET device according to the present invention, comprising a substrate (1), source and drain electrodes (5), an OSC layer (4), a dielectric layer (3), and a gate electrode (2), and an optional passivation or protection layer (6).

The device of Figure 2 can be prepared by a process comprising the steps of depositing S/D electrodes (5) on a substrate (1), depositing an OSC layer (4) on top of the S/D electrodes (4) and the substrate (1), depositing a dielectric layer (3) on top of the OSC layer (4), depositing a gate electrode (2) on top of the dielectric layer (3), and optionally depositing a passivation or protection layer (6) on top of the gate electrode (2) and the dielectric layer (3).

The passivation or protection layer (6) in the devices described in Figures 1A, 1 B and 2 has the purpose of protecting the OSC layer and the S/D or gate electrodes from further layers or devices that may be later provided thereon, and/or from environmental influence.

The distance between the source and drain electrodes (5), as indicated by the double arrow in Figures 1A, 1 B and 2, is the channel area.

In case of formulations for use in OPV cells, the formulation preferably comprises or contains, more preferably consists essentially of, very preferably exclusively of, a p-type semiconductor and a n-type semiconductor, or an acceptor and a donor material. A preferred material of this type is a blend or mixture of poly(3-substituted thiophene) or P3AT with a C ₆ o or C ₇₀ fullerene or modified C ₆ o molecule like PCBM [(6,6)-phenyl C61 -butyric acid methyl ester], as disclosed for example in WO 94/05045 A1 , wherein preferably the ratio of P3AT to fullerene is from 2:1 to 1 :2 by weight, more preferably from 1.2:1 to 1:1.2 by weight.

Figure 3 and Figure 4 exemplarily and schematically depict typical and preferred OPV devices according to the present invention [see also

Waldauf et al., Appl. Phys. Lett. 89, 233517 (2006)].

An OPV device as shown in Figure 3 preferably comprises:

- a low work function electrode (31) (for example a metal, such as

aluminum), and a high work function electrode (32) (for example ITO), one of which is transparent,

- a layer (33) (also referred to as "active layer") comprising a hole

transporting material and an electron transporting material, preferably selected from OSC materials, situated between the electrodes (31 ,32); the active layer can exist for example as a bilayer or two distinct layers or blend or mixture of p and n type semiconductor,

- an optional conducting polymer layer (34), for example comprising a blend of PEDOT:PSS (poly(3,4-ethylenedioxythiophene):

poly(styrenesulfonate)), situated between the active layer (33) and the high work function electrode (32), to modify the work function of the high work function electrode to provide an ohmic contact for holes,

- an optional coating (35) (for example of LiF) on the side of the low workfunction electrode (31) facing the active layer (33), to provide an ohmic contact for electrons.

An inverted OPV device as shown in Figure 4 preferably comprises: - a low work function electrode (41 ) (for example a metal, such as gold), and a high work function electrode (42) (for example ITO), one of which is transparent,

- a layer (43) (also referred to as "active layer") comprising a hole

transporting material and an electron transporting material, preferably selected from OSC materials, situated between the electrodes (41 ,42); the active layer can exist for example as a bilayer or two distinct layers or blend or mixture of p and n type semiconductor,

- an optional conducting polymer layer (44), for example comprising a blend of PEDOT.PSS, situated between the active layer (43) and the low work function electrode (41) to provide an ohmic contact for electrons,

- an optional coating (45) (for example of TiO _x ) on the side of the high workfunction electrode (42) facing the active layer (43), to provide an ohmic contact for holes.

The OPV devices of the present invent invention typically may comprise a p-type (electron donor) semiconductor and an n-type (electron acceptor) semiconductor. Preferably, the p-type semiconductor is for example a polymer like poly(3-alkyl-thiophene) (P3AT), preferably poly(3- hexylthiophene) (P3HT), or alternatively another selected from the groups of preferred polymeric and monomeric OSC material as listed above. The n-type semiconductor can be an inorganic material such as zinc oxide or cadmium selenide, or an organic material such as a fullerene derivate, for example (6,6)-phenyl C61 -butyric acid methyl ester, also known as "PCBM" or "PC ₆ iBM", as disclosed for example in G. Yu, J. Gao, J.C. Hummelen, F. Wudl, A.J. Heeger, Science 1995, Vol. 270, p. 1789 ff and having the structure shown below, or an structural analogous compound with e.g. a C ₇ i fullerene group (PC ₇₁ BM), or a polymer (see for example Coakley, K. M. and McGehee, M. D. Chem. Mater. 2004, 16, 4533).

PC ₆ iBM A preferred material of this type is a blend or mixture of a polymer like

P3HT or another polymer selected from the groups listed above, with a C ₆ o or C ₇ o fullerene or modified C60 fullerene like PC6 ₁ BM or PC7 ₁ BM.

Preferably the ratio polymenfullerene is from 2:1 to 1 :2 by weight, more preferably from 1.2:1 to 1 :1.2 by weight, most preferably 1 :1 by weight. For the blended mixture, an optional annealing step may be necessary to optimize blend morpohology and consequently OPV device performance.

During the process of preparing an OE device, the OSC layer is deposited onto a substrate, followed by removal of the solvent together with any volatile additive(s) present, to form a film or layer.

Various substrates may be used for the fabrication of OE devices, for example glass, ITO coated glass, ITO glass with pre coated layers including PEDOT, PANI etc, or plastics, plastics materials being preferred, examples including alkyd resins, allyl esters, benzocyclobutenes, butadiene-styrene, cellulose, cellulose acetate, epoxide, epoxy polymers, ethylene-chlorotrifluoro ethylene, ethylene-tetra-fluoroethylene, fibre glass enhanced plastic, fluorocarbon polymers, hexafluoropropylenevinylidene- fluoride copolymer, high density polyethylene, parylene, polyamide, polyimide, polyaramid, polydimethylsiloxane, polyethersulphone, polyethylene, polyethylenenaphthalate, polyethyleneterephthalate, polyketone, polymethylmethacrylate, polypropylene, polystyrene, polysulphone, polytetrafluoroethylene, polyurethanes, polyvinylchloride, silicone rubbers, silicones, and flexible films with ITO, or other conducting layers and barrier layers e.g. Vitex film.

Preferred substrate materials are polyethyleneterephthalate, polyimide, and polyethylenenaphthalate. The substrate may be any plastic material, metal or glass coated with the above materials. The substrate should preferably be homogeneous to ensure good pattern definition. The substrate may also be uniformly pre-aligned by extruding, stretching, rubbing or by

photochemical techniques to induce the orientation of the organic semiconductor in order to enhance carrier mobility.

The electrodes can be deposited by liquid coating, such as spray-, dip-, web- or spin-coating, or by vacuum deposition or vapor deposition methods. Suitable electrode materials and deposition methods are known to the person skilled in the art. Suitable electrode materials include, without limitation, inorganic or organic materials, or composites of the two.

Examples for suitable conductor or electrode materials include polyaniline, polypyrrole, PEDOT or doped conjugated polymers, further dispersions or pastes of graphite or particles of metal such as Au, Ag, Cu, Al, Ni or their mixtures as well as sputter coated or evaporated metals such as Cu, Cr, Pt/Pd or metal oxides such as indium tin oxide (ITO). Organometallic precursors may also be used deposited from a liquid phase.

Preferably, the substrate on surface on which the formulation according to the present invention is applied comprises a surface energy in the range of 130 to 25 mN m ^"1 more preferably in the range of 115 to 30 mN m ^" determined by measuring the contact angle of at least 2 solvents, e.g. water and methylene iodide, but other solvents can be used. These are typically measured using a contact angle goniometer such as a FTA 1000, at a temperature of 20 to 25°C (room temperature and at normal atmospheric pressure) the contact angle of the 2 solvents are then combined using a variety of mathematical models, typically Owens-Wendt geometric mean or Wu's harmonic mean. Preferably, the Owens-Wendt method is used.

Owens-Wendt formula

(1 + cos Θ) YLV = 2 V( Y ^d SV Y ^d LV ) + 2 V( γ ^ρ SV γ ^ρ LV )

Wu's Harmonic mean formula (1 + cos Θ) YLV = 4{ YD SVYD LV / ( γ° SV+γ ⁰ LV) + γ ^ρ SVY ^P LV / ( γ ^ρ SV+

Y ^P LV) }

Deposition of the OSC layer can be achieved by standard methods that are known to the skilled person and are described in the literature. Suitable and preferred deposition methods include liquid coating and printing techniques. Very preferred deposition methods include, without limitation, dip coating, spin coating, spray coating, aerosol jetting, ink jet printing, nozzle printing, gravure printing, doctor blade coating, roller printing, reverse-roller printing, flexographic printing, web printing, spray coating, dip coating, curtain coating, kiss coating, meyer bar coating, 2 roll nip fed coating, anilox coaters, knife coating or slot dye coating. Preferably, the OSC layer is applied with gravure printing, doctor blade coating, roller printing, reverse- roller printing, flexographic printing, web printing, anilox coaters. Gravure, flexographic and inkjet printing and variants of these printing methods are preferred. These include but or not limited to, micro gravure, reverse gravure.offset gravure, reverse roll etc. Both web fed(roll to roll) and sheetfed in both flatbed and the more conventional On the round' configurations can be used. For flexo printing the anilox can be either chromed steel or ceramic, preferably ceramic. The cell etch can vary between 2 cm ³ /m ² to 120 cm ³ /m ² but most pre-ferably between 3 cm ³ /m ² to 20 cm ³ /m ² and most preferably between 4 cm ³ /m ² to 18 cm ³ /m ² , however the dried film thickness will vary on the concentration of the active material and the transfer characteristics of said formulation. The cell configuration, i.e. shape, depth, cell wall linking can be adapted by a person skilled in the art to achieve an optimal printing result.

For gravure printing the chromed steel is preferably used but this does not exclude other materials. The engraving requirements are approximately 50% of those for the flexographic printing because there is one less transfer process involved.

The speed can vary significantly depending on the press type and configuration, for flatbed printing the print speed is typically very slow, typically 100 mm/minute or less. On roll to roll presses the speed can exceed 500 m/min.

According to a special aspect, an insulator layer can be deposited on a substrate in order to achieve a special type of an OE according to the present invention. Preferably, the insulator layer is deposited by solution processing, very preferably using a solution of a dielectric material, which is optionally cross-linkable, in one or more organic solvents. Preferably the solvent used for depositing the dielectric material is orthogonal to the solvent used for depositing the OSC material, and vice versa.

When spin coating is used as deposition method, the OSC or dielectric material is spun for example between 1000 and 2000 rpm for a period of for example 30 seconds to give a layer with a typical layer thickness between 0.5 and 1.5 μητι. After spin coating the film can be heated at an elevated temperature to remove all residual volatile solvents. If a cross-linkable dielectric is used, it is preferably cross-linked after deposition by exposure to electron beam or electromagnetic (actinic) radiation, like for example X-ray, UV or visible radiation. For example, actinic radiation can be used having a wavelength of from 50 nm to 700 nm, preferably from 200 to 450 nm, most preferably from 300 to 400 nm.

Suitable radiation dosages are typically in the range from 25 to 3,000 mJ/cm ² . Suitable radiation sources include mercury, mercury/xenon, mercury/halogen and xenon lamps, argon or xenon laser sources, x-ray, or e-beam. The exposure to actinic radiation will induce a cross-linking reaction in the cross-linkable groups of the dielectric material in the exposed regions. It is also possible for example to use a light source having a wavelength outside the absorption band of the cross-linkable groups, and to add a radiation sensitive photosensitizer to the cross-linkable material. Optionally the dielectric material layer is annealed after exposure to radiation, for example at a temperature from 70°C to 130°C, for example for a period of from 1 to 30 minutes, preferably from 1 to 10 minutes. The annealing step at elevated temperature can be used to complete the cross- linking reaction that was induced by the exposure of the cross-linkable groups of the dielectric material to photoradiation.

Removal of the solvent and any volatile additive(s) is preferably achieved by evaporation, for example by exposing the deposited layer to high temperature and/or reduced pressure, preferably at -50°C to 300°C, more preferably 20°C to 250°C. According to a special aspect of the present invention, the solvent(s) and any volatile additive can be evaporated under reduced pressure. Preferably either atmospheric pressure or reduced pressure the pressure for solvent evaporation ranges from 10 ^"3 mbar to 1 bar, especially from 10 ^"2 mbar to 100 mbar and more preferably from 0.1 mbar to 10 mbar. Moreover, the evaporation of the solvent can be preferably achieved below the boiling point of the solvent. The thickness of the dried OSC layer is preferably from 1 nm to 50 pm, especially from 2 to 1000 nm and more preferably 3 to 500 nm. Preferred layers comprising organic light emitting materials and/or charge

transporting materials can have a thickness in the range of 2 to 150 nm.

Further to the materials and methods as described above and below, the OE device and its components can be prepared from standard materials and standard methods, which are known to the person skilled in the art and described in the literature.

It will be appreciated that variations to the foregoing embodiments of the invention can be made while still falling within the scope of the 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. Unless the context clearly indicates otherwise, as used herein plural forms of the terms herein are to be construed as including the singular form and vice versa.

Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of the words, for example

"comprising" and "comprises", mean "including but not limited to", and are not intended to (and do not) exclude other components.

The term "polymer" includes homopolymers and copolymers, e.g.

statistical, alternating or block copolymers. In addition, the term "polymer" as used hereinafter does also include oligomers and dendrimers.

Dendrimers are typically branched macromolecular compounds consisting of a multifunctional core group onto which further branched monomers are added in a regular way giving a tree-like structure, as described e.g. in M. Fischer and F. Vogtle, Angew. Chem., Int. Ed. 1999, 38, 885.

The term "conjugated polymer" means a polymer containing in its backbone (or main chain) mainly C atoms with sp ² -hybridisation, or optionally sp- hybridisation, which may also be replaced by hetero atoms, enabling interaction of one π-orbital with another across an intervening σ-bond. In the simplest case this is for example a backbone with alternating carbon- carbon (or carbon-hetero atom) single and multiple (e.g. double or triple) bonds, but does also include polymers with units like 1 ,3-phenylene.

"Mainly" means in this connection that a polymer with naturally

(spontaneously) occurring defects, which may lead to interruption of the conjugation, is still regarded as a conjugated polymer. Also included in this meaning are polymers wherein the backbone comprises for example units like aryl amines, aryl phosphines and/or certain heterocycles (i.e.

conjugation via N-, 0-, P- or S-atoms) and/or metal organic complexes (i.e. conjugation via a metal atom). The term "conjugated linking group" means a group connecting two rings (usually aromatic rings) consisting of C atoms or hetero atoms with sp ² -hybridisation or sp-hybridisation. See also "lUPAC Compendium of Chemical terminology, Electronic version".

Unless stated otherwise, the molecular weight is given as the number average molecular weight M _n or as weight average molecular weight M _w , which unless stated otherwise are determined by gel permeation chromatography (GPC) against polystyrene standards.

The degree of polymerization (n) means the number average degree of polymerization, unless stated otherwise given as n = Mp/Mu, wherein Mu is the molecular weight of the single repeating unit.

The term "small molecule" means a monomeric, i.e. a non-polymeric compound.

Unless stated otherwise, percentages of solids are per cent by weight ("wt. %"), percentages or ratios of liquids (like e.g. in solvent mixtures) are per cent by volume ("vol. %"), and all temperatures are given in degrees Celsius (°C).

Unless stated otherwise, concentrations or proportions of mixture components, given in percentages or ppm are related to the entire formulation including the solvents. The invention will now be described in more detail by reference to the following examples, which are illustrative only and do not limit the scope of the present invention.

All process steps described above and below can be carried out using known techniques and standard equipment which are described in prior art and are well-known to the skilled person. Comparative Example 1

A printing ink was prepared by mixing a phosphorescent compound according to formula C-1

and host materials having the formula C-2

and host materials having the

form -3

0.0100 g of Compound C-1 was weighted into a glass vial, followed by weighting 0.0200 g of Compound C-2, and 0.0200 g of Compound C-3. To this 3 ml of anisole was added by using 3 1 ml aliquots from a Eppendorf pipette. A small magnetic stirrer bar was added and the glass vial was sealed. This was warmed to -35 to 40°C and stirred for 2 hours to ensure - I n complete dissolution of the solid materials. After dissolving the lid was removed and helium was bubbled through for 20 minutes in order to degas, after this the container was placed in a vacuum desicator and left overnight to remove the Helium.

2 ml of the ink was filtered using a 0.45 μ filter (25 mm diameter ex

Millipore) into a LCP cartridge for use with a Dimatix DMP2831 printer. The head of the cartridge was put into position and then inserted into the ink-jet printer.

A full ink jet test was performed to assess the print performance of the ink, ink-jet behaviour was observed and commented on. Ink-jet waveform was optimised, and the effects of changing the voltage/frequency and pulse width on droplet velocity were also assessed.

The prepared ink was printed onto a 25 mm x 25 mm glass slide that was cleaned by placing in methanol in an ultrasonic bath for 10 minutes at 70°C. After this the methanol was dried off and the substrate was placed on to a hot plate set at 150°C for 15 minutes. The glass slide was removed and a preparation of 0.5 % HIL-012 in Mesitylene was spin coated onto the slide at a speed of 1300 rpm to give a final HIL12 coating thickness of 20 nm.

The ink was printed using a 2 mm x 2 mm square pattern; this was printed at 20 μ, 40 μ, 60 μ, 80 μ and 100 μ drop spacing (ds), the different drop spacings were achieved by angulating the printing head. The printing was performed at different temperatures namely 25°C, 30°C, 40°C, 50°C and 60°C.

The jetting stability was poor. Nozzle plate wetting was moderate. A two droplet system was observed from this ink.The anisole based ink did not wet the HIL-012 coated substrate well, the swaths did not merge when using 40 μ, 60 μ, 80 μ and 100 μ ds. The printing performed better using 20 μ ds with better wetting but drying fronts seen on the film and significant coffee staining is evident.

Comparative example 2

Essentially, Comparative Example 1 was repeated. However, 4-methylani- sole has been used as solvent. The HIL-012 layer was wetted acceptable for 20 μ to 60 μ ds. The printing quality was acceptable for 40 μ to 60 μ ds. The jetting stability was moderately poor. Nozzle plate wetting was moderately poor. A two droplet system was observed from this ink.

However, the results are improved in comparison to the Comparative example 1.

Example 1

Essentially, Comparative Example 1 was repeated. However, 2,4-dimethyl- anisole has been used as solvent. The HIL-012 layer was wetted acceptable for 20 μ to 80 μ ds. The printing quality was acceptable for 40 μ to 60 μ ds. The jetting stability was fair. Nozzle plate wetting was slight. A two droplet system was observed from this ink. However, the results are improved in comparison to the Comparative example 2.

Example 2

Essentially, Comparative Example 1 was repeated. However, 2,5-dimethyl- anisole has been used as solvent. The HIL-012 layer was wetted acceptable for 20 μ to 80 μ ds. The printing quality was acceptable for 40 μ to 60 μ ds. The jetting stability was fair. Nozzle plate wetting was slight. The coalescence distance was 250 μιη (single droplets formed). However, the results are improved in comparison to the Example 1.

Example 3 Essentially, Comparative Example 1 was repeated. However, 2,6-dimethyl- anisole has been used as solvent. The HIL-0 2 layer was wetted acceptable for 20 μ to 80 μ ds. The printing quality was acceptable for 40 μ to 60 μ ds. The jetting stability was good. Nozzle plate wetting was fair. The coalescence distance was 250 pm. However, the results are improved in comparison to the Example 1.

Example 4

Essentially, Comparative Example 1 was repeated. However, 3,4-dimethyl- anisole has been used as solvent. The HIL-012 layer was wetted acceptable for 20 μ to 100 μ ds. The printing quality was good or at least acceptable for 40 μ to 80 μ ds depending on the printing temperature. The jetting stability was good. Nozzle plate wetting was good (none). The coalescence distance was 300 pm. However, the results are improved in comparison to the Examples 2 and 3, respectively.