Compounds of the formula, where the following applies to the symbols and indices used: Ar is on each occurrence, identically or differently, an aryl group having 6 to 16 aromatic ring atoms, which may be substituted by one or more radicals R 1; R stands on each occurrence, identically or differently, for Si(R 2) 3, N(Ar 1) 2, C(=O)Ar 1, P(=O)(Ar 1) 2, a straight-chain alkyl or alkoxy group having 1 to 10 C atoms or a branched or cyclic alkyl or alkoxy group having 3 to 10 C atoms, each of which may be substituted by one or more radicals R 2, where one or more non-adjacent CH 2 groups may be replaced by -R 2 C=CR 2 - or -O- and where one or more H atoms may be replaced by F, or for an aryl group having 5 to 16 aromatic ring atoms, which may be substituted by one or more radicals R 2, or a combination of two, three or four of these systems; adjacent substituents R and R 1 here may also form a mono- or polycyclic, aliphatic ring system with one another; R 1 stands on each occurrence, identically or differently, for Si(R 2) 3, F, N(Ar 1) 2, a straight-chain alkyl or alkoxy group having 1 to 6 C atoms or a branched or cyclic alkyl or alkoxy group having 3 to 10 C atoms, where in each case one or more CH 2 groups may be replaced by -R 2 C=CR 2 - or -O- and where in each case one or more H atoms may be replaced by F, or for an aryl group having 5 to 14 aromatic ring atoms, which may be substituted by one or more radicals R 2, or a combination of two or three of these systems; two or more radicals R 1 here may also form a mono- or polycyclic, aliphatic ring system with one another or with an adjacent radical R; Ar 1 is on each occurrence, identically or differently, an aromatic ring system having 5 to 30 aromatic ring atoms, which may be substituted by one or more non-aromatic radicals R 1; two radicals Ar 1 here may also be connected to one another by a single bond or a group O, S, N(R 2) or C(R 2) 2; R 2 is on each occurrence, identically or differently, H or a hydrocarbon radical having 1 to 20 C atoms, which may be aliphatic or aromatic or a combination of aliphatic and aromatic and which may also be substituted by F; two or more radicals R 2 here may also form a mono- or polycyclic, aliphatic or aromatic ring system with one another; n is, identically or differently on each occurrence, 0, 1, 2 or 3; p is, identically or differently on each occurrence, 0, 1, 2, 3 or 4. Ar is on each occurrence, identically or differently, an aryl group having 6 to 16 aromatic ring atoms, which may be substituted by one or more radicals R 1; R stands on each occurrence, identically or differently, for Si(R 2) 3, N(Ar 1) 2, C(=O)Ar 1, P(=O)(Ar 1) 2, a straight-chain alkyl or alkoxy group having 1 to 10 C atoms or a branched or cyclic alkyl or alkoxy group having 3 to 10 C atoms, each of which may be substituted by one or more radicals R 2, where one or more non-adjacent CH 2 groups may be replaced by -R 2 C=CR 2 - or -O- and where one or more H atoms may be replaced by F, or for an aryl group having 5 to 16 aromatic ring atoms, which may be substituted by one or more radicals R 2, or a combination of two, three or four of these systems; adjacent substituents R and R 1 here may also form a mono- or polycyclic, aliphatic ring system with one another; R 1 stands on each occurrence, identically or differently, for Si(R 2) 3, F, N(Ar 1) 2, a straight-chain alkyl or alkoxy group having 1 to 6 C atoms or a branched or cyclic alkyl or alkoxy group having 3 to 10 C atoms, where in each case one or more CH 2 groups may be replaced by -R 2 C=CR 2 - or -O- and where in each case one or more H atoms may be replaced by F, or for an aryl group having 5 to 14 aromatic ring atoms, which may be substituted by one or more radicals R 2, or a combination of two or three of these systems; two or more radicals R 1 here may also form a mono- or polycyclic, aliphatic ring system with one another or with an adjacent radical R; Ar 1 is on each occurrence, identically or differently, an aromatic ring system having 5 to 30 aromatic ring atoms, which may be substituted by one or more non-aromatic radicals R 1; two radicals Ar 1 here may also be connected to one another by a single bond or a group O, S, N(R 2) or C(R 2) 2; R 2 is on each occurrence, identically or differently, H or a hydrocarbon radical having 1 to 20 C atoms, which may be aliphatic or aromatic or a combination of aliphatic and aromatic and which may also be substituted by F; two or more radicals R 2 here may also form a mono- or polycyclic, aliphatic or aromatic ring system with one another; n is, identically or differently on each occurrence, 0, 1, 2 or 3; p is, identically or differently on each occurrence, 0, 1, 2, 3 or 4.