Compositions comprising polymeric binders
View Patent ↗The present invention relates to novel compositions comprising light emitting materials and/or charge transport materials and a polymeric binder, to their use as conducting inks for the preparation of organic light emitting diode (OLED) devices, to methods for preparing OLED devices using the novel formulations, and to OLED devices prepared from such methods and formulations.
1. A composition comprising one or more organic light emitting materials and/or charge transport materials having a molecular weight of at most 5000 g/mol, one or more organic solvents, and one or more polymers, wherein said polymer is an inert binder which does not have semiconducting properties and wherein the weight ratio of the one or more polymers to the one or more light emitting materials and/or charge transport materials is in the range of 1:2 to 1:5.
2. The composition according to claim 1 , wherein said composition comprises a surface tension in the range of 20 mN/m to 60 mN/m.
3. The composition according to claim 1 , wherein said inert binder is a polymer comprising repeating units derived from styrene monomers and/or olefins.
4. The composition according to claim 1 , wherein said inert binder is a polymer having a weight average molecular weight of at least 100,000 g/mol.
5. The composition according to claim 1 , wherein the composition comprises a viscosity at 25° C. in the range of 1.5 to 100 mPas.
6. The composition according to claim 1 , wherein the inert binder is a polymer having a glass transition temperature in the range of −70 to 160° C.
7. The composition according to claim 1 , wherein said composition comprises in the range of 0.25 to 5% by weight of said inert binders.
8. The composition according to claim 1 , wherein said organic solvent is an aromatic compound.
9. The composition according to claim 8 , wherein said organic solvent is selected from the group consisting of aromatic ethers, aromatic esters, aromatic ketones, heteroaromatic solvents and aniline derivatives.
10. The composition according to claim 1 , wherein said organic solvent comprises a boiling point of at most 260° C.
11. The composition according to claim 1 , wherein said composition comprises at least 80% by weight of said organic solvents.
12. The composition according to claim 1 , wherein more organic light emitting materials and/or charge transport materials having a molecular weight of at most 5,000 g/mol is an organic phosphorescent compound which emits light and in addition contains at least one atom having an atomic number greater than 38.
13. The composition according to claim 12 , wherein the phosphorescent compound is a compound of formulae (1) to (4):
where
DCy is, identically or differently on each occurrence, a cyclic group which contains at least one donor atom, via which the cyclic group is bonded to the metal, and which may in turn carry one or more substituents R 1 ; 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 1 ;
A is, identically or differently on each occurrence, a monoanionic, bidentate chelating ligand;
R 1 are identically or differently at each instance, and are F, Cl, Br, I, NO 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 CH 2 groups may be replaced by —O—, —S—, —NR 2 —, —CONR 2 —, —CO—O—, —C═O—, —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 1 radicals, and a plurality of substituents R 1 , either on the same ring or on the two different rings, may together in turn form a mono- or polycyclic, aliphatic or aromatic ring system; and
R 2 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 —O—, —S—, —CO—O—, —C═O—, —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 1 radicals.
14. The composition according to claim 13 , wherein
DCy is, identically or differently on each occurrence, a cyclic group which contains at least 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 1 ; the groups DCy and CCy are connected to one another via a covalent bond; and
A is a diketonate ligand.
15. The composition according to claim 1 , wherein the composition comprises 0.5 to 5% by weight organic light emitting materials and/or charge transport materials having a molecular weight of at most 5000 g/mol.
16. A coating or printing ink for the preparation of OLED device which comprises the composition according to claim 1 .
17. An OLED device prepared from the composition according to claim 1 .