Materials for organic electroluminescent devices

1. A compound of formula I

wherein

R is selected on each occurrence, identically or differently, from the group consisting of F, CN, NO 2 , ArNAr 2 , NAr 2 , C(═O)Ar, C(═O)R 2 , P(═O)Ar 2 , S(═O)Ar, S(═O) 2 Ar, —CR 2 ═C(R 2 ) 2 and a mono- or polycyclic aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms, optionally substituted by one or more non-aromatic radicals R 1 ; two radicals Ar which are bonded to the same nitrogen or phosphorus atom are optionally linked to one another by a single bond or a bridge selected from B(R 2 ), C(R 2 ) 2 , Si(R 2 ) 2 , C═O, C═NR 2 , C═C(R 2 ) 2 , O, S, S═O, SO 2 , N(R 2 ), P(R 2 ) and P(═O)R 2 ;

R 1 is selected, identically or differently on each occurrence, from the group consisting of H, D, F, OH, CN, a straight-chain alkyl, alkoxy or thioalkoxy group having 1 to 40 C atoms and a branched or cyclic alkyl, alkoxy or thioalkoxy group having 3 to 40 C atoms or an alkenyl group having 2 to 40 C atoms, each of which is optionally substituted by one or more radicals R 2 , where one or more non-adjacent CH 2 groups is optionally replaced by R 2 C═CR 2 , C≡C, Si(R 2 ) 2 , C═O, C═S, C═NR 2 , P(═O)(R 2 ), SO, SO 2 , NR 2 , O or S and where one or more H atoms is optionally replaced by D, F, Cl, Br, I, CN or NO 2 ; where, in addition, the respective R 1 which is located in the vicinal position to the radical R, in the case where R is an aromatic or heteroaromatic ring system, is optionally a divalent unit which is linked to the group R;

Ar 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 1 ;

R 2 is selected on each occurrence, identically or differently, from the group consisting of H, D, F, CN and an aliphatic, aromatic or heteroaromatic hydrocarbon radical having 1 to 20 C atoms, in which, in addition, one or more H atoms may be replaced by 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; two or more adjacent substituents R 2 may also be linked to one another by a covalent bond or also, in the case where the R 2 involved are aromatic or heteroaromatic hydrocarbon radicals, by one or more divalent aliphatic hydrocarbon units.

2. The compound of claim 1 , wherein R is selected from the group consisting of NAr 2 , C(═O)R 2 , CR 2 ═CR 2 2 and a mono- or polycyclic aromatic or heteroaromatic ring system having 5 to 40 aromatic ring atoms, optionally substituted by one or more non-aromatic radicals R 1 ; where, in addition, two radicals Ar which are bonded to the same nitrogen atom are optionally linked to one another by a single bond or a bridge selected from C(R 2 ) 2 , C═O, O, S and N(R 2 ).

3. The compound of claim 1 , wherein R is on each occurrence, identically or differently, NAr 2 or a mono- or polycyclic aromatic or heteroaromatic ring system having 5 to 20 aromatic ring atoms.

4. The compound of claim 1 , wherein R is selected, identically or differently, from the group consisting of the following radicals:

where the dashed line in the groups is intended to indicate that the group is bonded at this position, and where s and q are each, independently of one another, 0 or 1, where, for s=0 or q=0, the R 1 in question is replaced by an H, and E is selected from the group consisting of C(R 1 ) 2 , NR 1 , O, C═O, S, S═O and S(O) 2 .

5. The compound of claim 1 , wherein R 1 is selected, identically or differently on each occurrence, from the group consisting of H, D, F, CN, a straight-chain alkyl, alkoxy or thioalkoxy group having 1 to 20 C atoms and a branched or cyclic alkyl, alkoxy or thioalkoxy group having 3 to 20 C atoms; where, in addition, the respective R 1 which is located in the vicinal position to the radical R is optionally a divalent unit, which is optionally linked to the aromatic or heteroaromatic ring system of the group R.

6. The compound of claim 1 , wherein Ar is an aromatic or heteroaromatic ring system having 5 to 14 aromatic ring atoms.

7. The compound of claim 1 , wherein said compound is a compound of formula II or III:

8. A process for preparing the compound of claim 1 comprising the step of coupling a spirobifluorene or a spirobifluorene derivative which is substituted in the 4,4′-position by a reactive leaving group to a functionalised aromatic compound or to a mono- or disubstituted amine.

9. A mixture comprising at least one compound according to claim 1 and at least one further compound.

10. A formulation or solution comprising at least one compound according to claim 1 and at least one solvent.

11. An electronic device comprising at least one compound according to claim 1 .

12. The electronic device of claim 11 , wherein said electronic device is selected from the group consisting of organic electroluminescent devices, organic field-effect transistors, organic thin-film transistors, organic light-emitting transistors, organic integrated circuits, organic solar cells, organic field-quench devices, light-emitting electrochemical cells, organic laser diodes, and organic photoreceptors.

13. The electronic device of claim 12 , wherein said electronic device is an organic electroluminescent device, and wherein the at least one compound of claim 1 is employed as host material for fluorescent or phosphorescent dopants.

14. The electronic device of claim 12 , wherein said electronic device is an organic electroluminescent device, and wherein the at least one compound of claim 1 is employed as emitting material, as hole-transport material, as hole-injection material, or as electron-transport material.

15. The compound of claim 1 , wherein R 1 is selected, identically or differently, from the group consisting of H, D, F, and CN.

16. The compound of claim 1 , wherein R 1 is in each case hydrogen.

17. A formulation or solution comprising at least one mixture according to claim 9 and at least one solvent.

18. An electronic device comprising at least one mixture according to claim 9 .

19. An electronic device comprising at least one solution or formulation according to claim 10 .