Formulation of an organic functional material

1. A formulation comprising at least one organic functional material selected from the group consisting of fluorescent emitters, phosphorescent emitters, host materials, exciton-blocking materials, electron-transport materials, electron-injection materials, hole-transporting materials, hole-injection materials, n-dopants, p-dopants, wide-band-gap materials, electron-blocking materials and hole-blocking materials;

and at least a first organic solvent, wherein said first organic solvent contains at least one norbornene group and is a solvent according to general formula (I)

wherein

R 1 , R 2 and R 3 are identical or different at each occurrence, and are H, D, F, Cl, Br, I, NO 2 , CN, a straight-chain alkyl or alkoxy group having from 1 to 20 carbon atoms or a branched or cyclic alkyl or alkoxy group having from 3 to 20 carbon atoms, in which one or more non-adjacent CH 2 groups may be replaced by —O—, —S—, —NR 5 —, —CONR 5 —, —CO—O— or —C═O—, 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 straight-chain alkyl or alkoxy group having from 1 to 20 carbon atoms or a branched or cyclic alkyl or alkoxy group having from 3 to 20 carbon atoms, in which one or more non-adjacent CH 2 groups may be replaced by —O—, —S—, —CO—O— or —C═O—, and in which one or more hydrogen atoms may be replaced by F, and a plurality of substituents R 5 , either on the same ring or on the two different rings, may together in turn form a mono- or polycyclic, aliphatic, aromatic or heteroaromatic ring system, which may be substituted by a plurality of substituents R 5 ;

Sp is a straight-chain alkylene group having from 1 to 20 carbon atoms or a branched alkylene group having from 3 to 20 carbon atoms, in which one or more non-adjacent CH 2 groups may be replaced by —O—, —S—, —NR 5 —, —CONR 5 —, —O—CO—, —CO—O— or —C═O—;

R 4 is H, D, F, Cl, Br, I, NO 2 , CN or a mono- or polycyclic, alicyclic or heterocyclic ring system, which has from 3 to 14 ring atoms, a mono- or polycyclic aromatic ring system, which has from 6 to 14 ring atoms, or a mono- or polycyclic heteroaromatic ring system, which has from 5 to 14 ring atoms, each of these ring systems may be substituted by one or more straight-chain alkyl or alkoxy group having from 1 to 20 carbon atoms or a branched or cyclic alkyl or alkoxy group having from 3 to 20 carbon atoms, in which one or more non-adjacent CH 2 groups may be replaced by —O—, —S—, —CO—O— or —C═O—, and in which one or more hydrogen atoms may be replaced by F;

R 5 are identical or different at each instance, and are a straight-chain alkyl or alkoxy group having from 1 to 20 carbon atoms or a branched or cyclic alkyl or alkoxy group having from 3 to 20 carbon atoms, in which one or more non-adjacent CH 2 groups may be replaced by —O—, —S—, —CO—O— or —C═O—, 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 straight-chain alkyl or alkoxy group having from 1 to 20 carbon atoms or a branched or cyclic alkyl or alkoxy group having from 3 to 20 carbon atoms, in which one or more non-adjacent CH 2 groups may be replaced by —O—, —S—, —CO—O— or —C═O—, and in which one or more hydrogen atoms may be replaced by F, and a plurality of substituents R 5 , 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, which may be substituted by a plurality of substituents R 5 .

2. The formulation according to claim 1 , wherein the first organic solvent, which contains at least one norbornene group, is a solvent according to general formula (I), wherein

R 1 , R 2 and R 3 are H;

Sp is a straight-chain alkylene group having from 1 to 20 carbon atoms or a branched alkylene group having from 3 to 20 in which one or more non-adjacent CH 2 groups may be replaced by —O—, —S—, —NR 5 —, —CONR 5 —, —O—CO—, —CO—O— or —C═O—;

R 4 is H, or a mono- or polycyclic, alicyclic or heterocyclic ring system, which has from 3 to 14 ring atoms, a mono- or polycyclic aromatic ring system, which has from 6 to 14 ring atoms, or a mono- or polycyclic heteroaromatic ring system, which has from 5 to 14 ring atoms, each of these ring systems may be substituted by one or more straight-chain alkyl or alkoxy group having from 1 to 20 carbon atoms or a branched or cyclic alkyl or alkoxy group having from 3 to 20 carbon atoms, in which one or more non-adjacent CH 2 groups may be replaced by —O—, —S—, —CO—O— or —C═O—, and in which one or more hydrogen atoms may be replaced by F;

R 5 are identical or different at each instance, and are a straight-chain alkyl or alkoxy group having from 1 to 20 carbon atoms or a branched or cyclic alkyl or alkoxy group having from 3 to 20 carbon atoms, in which one or more non-adjacent CH 2 groups may be replaced by —O—, —S—, —CO—O— or —C═O—, 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 straight-chain alkyl or alkoxy group having from 1 to 20 carbon atoms or a branched or cyclic alkyl or alkoxy group having from 3 to 20 carbon atoms, in which one or more non-adjacent CH 2 groups may be replaced by —O—, —S—, —CO—O— or —C═O—, and in which one or more hydrogen atoms may be replaced by F.

3. The formulation according to claim 1 , wherein the first organic solvent, which contains at least one norbornene group, is a solvent according to general formula (I), wherein

R 1 , R 2 and R 3 are H;

Sp is a straight-chain alkylene group having from 1 to 20 carbon atoms or a branched alkylene group having from 3 to 20 carbon atoms, in which one or more non-adjacent CH 2 groups may be replaced by —O—, —S—, —NR 5 —, —CONR 5 —, —O—CO—, —CO—O— or —C═O—;

R 4 is H;

R 5 are identical or different at each instance, and are a straight-chain alkyl or alkoxy group having from 1 to 20 carbon atoms or a branched or cyclic alkyl or alkoxy group having from 3 to 20 carbon atoms, in which one or more non-adjacent CH 2 groups may be replaced by —O—, —S—, —CO—O— or —C═O—, 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 straight-chain alkyl or alkoxy group having from 1 to 20 carbon atoms or a branched or cyclic alkyl or alkoxy group having from 3 to 20 carbon atoms, in which one or more non-adjacent CH 2 groups may be replaced by —O—, —S—, —CO—O— or —C═O—, and in which one or more hydrogen atoms may be replaced by F.

4. The formulation according to claim 1 , wherein the first organic solvent, which contains at least one norbornene group, is a solvent according to general formula (I), wherein

R 1 , R 2 and R 3 are H;

Sp is a straight-chain alkylene group having from 1 to 20 carbon atoms or a branched alkylene group having from 3 to 20 in which one or more nonadjacent CH 2 groups may be replaced by —O—, —S—, —NR 5 —, —CONR 5 —, —O—CO—, —CO—O— or —C═O—;

R 4 is a mono- or polycyclic, aromatic ring system, which has from 6 to 14 ring atoms and may be substituted by one or more nonaromatic R 5 radicals or a mono- or polycyclic, heteroaromatic ring system, which has from 5 to 14 ring atoms and may be substituted by one or more straight-chain alkyl or alkoxy group having from 1 to 20 carbon atoms or a branched or cyclic alkyl or alkoxy group having from 3 to 20 carbon atoms, in which one or more non-adjacent CH 2 groups may be replaced by —O—, —S—, —CO—O— or —C═O—, and in which one or more hydrogen atoms may be replaced by F;

R 5 are identical or different at each instance, and are a straight-chain alkyl or alkoxy group having from 1 to 20 carbon atoms or a branched or cyclic alkyl or alkoxy group having from 3 to 20 carbon atoms, in which one or more non-adjacent CH 2 groups may be replaced by —O—, —S—, —CO—O— or —C═O—, 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 straight-chain alkyl or alkoxy group having from 1 to 20 carbon atoms or a branched or cyclic alkyl or alkoxy group having from 3 to 20 carbon atoms, in which one or more non-adjacent CH 2 groups may be replaced by —O—, —S—, —CO—O— or —C═O—, and in which one or more hydrogen atoms may be replaced by F.

5. The formulation according to claim 1 , wherein the first organic solvent, which contains at least one norbornene group, is a solvent according to general formula (I), wherein

R 1 , R 2 and R 3 are H;

Sp is a straight-chain alkylene group having from 1 to 20 carbon atoms or a branched alkylene group having from 3 to 20 carbon atoms, in which one or more non-adjacent CH 2 groups may be replaced by —O—, —S—, —NR 5 —, —CONR 5 —, —O—CO—, —CO—O— or —C═O—;

R 4 is a mono- or polycyclic, alicyclic or heterocyclic ring system, which has from 3 to 14 ring atoms and may be a straight-chain alkyl or alkoxy group having from 1 to 20 carbon atoms or a branched or cyclic alkyl or alkoxy group having from 3 to 20 carbon atoms, in which one or more non-adjacent CH 2 groups may be replaced by —O—, —S—, —CO—O— or —C═O—, and in which one or more hydrogen atoms may be replaced by F;

R 5 are identical or different at each instance, and are a straight-chain alkyl or alkoxy group having from 1 to 20 carbon atoms or a branched or cyclic alkyl or alkoxy group having from 3 to 20 carbon atoms, in which one or more non-adjacent CH 2 groups may be replaced by —O—, —S—, —CO—O— or —C═O—, 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 straight-chain alkyl or alkoxy group having from 1 to 20 carbon atoms or a branched or cyclic alkyl or alkoxy group having from 3 to 20 carbon atoms, in which one or more non-adjacent CH 2 groups may be replaced by —O—, —S—, —CO—O— or —C═O—, and in which one or more hydrogen atoms may be replaced by F.

6. The formulation according to claim 1 , wherein the first solvent has a surface tension of ≥20 mN/m.

7. The formulation according to claim 1 , wherein the content of the first solvent is in the range from 50 to 100 vol.-%, based on the total amount of solvents in the formulation.

8. The formulation according to claim 1 , wherein the first solvent has a boiling point in the range from 100 to 400° C.

9. The formulation according to claim 1 , wherein the formulation comprises at least one second solvent which is different from the first solvent.

10. The formulation according to claim 9 , wherein the second solvent has a boiling point in the range from 100 to 400° C.

11. The formulation according to claim 9 , wherein the at least one organic functional material has a solubility in the first as well as in the second solvent in the range from 1 to 250 g/l.

12. The formulation according to claim 1 , wherein the formulation has a surface tension in the range from 1 to 70 mN/m.

13. The formulation according to claim 1 , wherein the formulation has a viscosity in the range from 1 to 50 mPa·s.

14. The formulation according to claim 1 , wherein the content of the at least one organic functional material in the formulation is in the range from 0.001 to 20 weight-%, based on the total weight of the formulation.

15. The formulation according to claim 1 , wherein the hole-injecting material or the hole-transporting material is a polymeric compound or a blend of a polymeric compound and a non-polymeric compound.

16. A process for the preparation of a formulation according to claim 1 , comprising mixing the at least one organic functional material and the first solvent.

17. A process for the preparation of an electroluminescent device comprising preparing at least one layer by applying a formulation according to claim 1 on a substrate and subsequently drying the formulation.