Compound of the formula where: A is a group of the formula formula, which is bonded via the dashed bond; Ar 1 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; Y is on each occurrence, identically or differently, a single bond, BR 1, C(R 1) 2, Si(R 1) 2, NR 1, PR 1, P(=O)R 1, O, S, S=O oder S(=O) 2; B is selected on each occurrence, identically or differently, from H, a straight-chain alkyl group having 1 to 10 C atoms, a branched or cyclic alkyl group having 3 to 10 C atoms, which may in each case be substituted by one or more radicals R 1, and an aryl group having 6 to 14 aromatic ring atoms, which may in each case be substituted by one or more radicals R 1; R A is on each occurrence, identically or differently, F, CF 3, CN, or a group E, which is an aryl or heteroaryl group having 6 to 14 aromatic ring atoms, which may be substituted by one or more radicals R 1, and which contains, as constituents of the aromatic ring, one or more groups V, where the groups V are selected on each occurrence, identically or differently, from =N-, =C -, =C - and =C(CF 3)-, and where the heteroaryl group is not bonded via a nitrogen atom; R B is selected from H, a straight-chain alkyl group having 1 to 10 C atoms or a branched or cyclic alkyl group having 3 to 10 C atoms, which may in each case be substituted by one or more radicals R 1, and an aryl group having 6 to 14 aromatic ring atoms, which may be substituted by one or more radicals R 1; R 1 is on each occurrence, identically or differently, H, D, F, C(=O)R 2, CN, Si(R 2) 3, N(R 2) 2, P(=O)(R 2) 2, OR 2, S(=O)R 2, S(=O) 2 R 2, a straight-chain alkyl or alkoxy group having 1 to 20 C atoms or a branched or cyclic alkyl or alkoxy group hav-ing 3 to 20 C atoms, where the above-mentioned groups may in each case be substituted by one or more radicals R 2 and where one or more CH 2 groups in the above-mentioned groups may be replaced by -R 2 C=CR 2 -, -C=C-, Si(R 2) 2, C=O, C=NR 2, -C(=O)O-, -C(=O)NR 2 -, NR 2, P(=O)(R 2), -O-, -S-, SO or SO 2, or an aromatic or heteroaromatic ring system having 5 to 30 aromatic ring atoms, which may in each case be substituted by one or more radicals R 2, where two or more radicals R 1 may be linked to one another and may form a ring; R 2 is on each occurrence, identically or differently, H, D, F or an aliphatic, aromatic or heteroaromatic organic radical having 1 to 20 C atoms, in which, in addition, one or more H atoms may be replaced by D or F; two or more substituents R 2 here may be linked to one another and may form a ring; where the following compounds are excluded: A is a group of the formula formula, which is bonded via the dashed bond; Ar 1 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; Y is on each occurrence, identically or differently, a single bond, BR 1, C(R 1) 2, Si(R 1) 2, NR 1, PR 1, P(=O)R 1, O, S, S=O oder S(=O) 2; B is selected on each occurrence, identically or differently, from H, a straight-chain alkyl group having 1 to 10 C atoms, a branched or cyclic alkyl group having 3 to 10 C atoms, which may in each case be substituted by one or more radicals R 1, and an aryl group having 6 to 14 aromatic ring atoms, which may in each case be substituted by one or more radicals R 1; R A is on each occurrence, identically or differently, F, CF 3, CN, or a group E, which is an aryl or heteroaryl group having 6 to 14 aromatic ring atoms, which may be substituted by one or more radicals R 1, and which contains, as constituents of the aromatic ring, one or more groups V, where the groups V are selected on each occurrence, identically or differently, from =N-, =C -, =C - and =C(CF 3)-, and where the heteroaryl group is not bonded via a nitrogen atom; R B is selected from H, a straight-chain alkyl group having 1 to 10 C atoms or a branched or cyclic alkyl group having 3 to 10 C atoms, which may in each case be substituted by one or more radicals R 1, and an aryl group having 6 to 14 aromatic ring atoms, which may be substituted by one or more radicals R 1; R 1 is on each occurrence, identically or differently, H, D, F, C(=O)R 2, CN, Si(R 2) 3, N(R 2) 2, P(=O)(R 2) 2, OR 2, S(=O)R 2, S(=O) 2 R 2, a straight-chain alkyl or alkoxy group having 1 to 20 C atoms or a branched or cyclic alkyl or alkoxy group hav-ing 3 to 20 C atoms, where the above-mentioned groups may in each case be substituted by one or more radicals R 2 and where one or more CH 2 groups in the above-mentioned groups may be replaced by -R 2 C=CR 2 -, -C=C-, Si(R 2) 2, C=O, C=NR 2, -C(=O)O-, -C(=O)NR 2 -, NR 2, P(=O)(R 2), -O-, -S-, SO or SO 2, or an aromatic or heteroaromatic ring system having 5 to 30 aromatic ring atoms, which may in each case be substituted by one or more radicals R 2, where two or more radicals R 1 may be linked to one another and may form a ring; R 2 is on each occurrence, identically or differently, H, D, F or an aliphatic, aromatic or heteroaromatic organic radical having 1 to 20 C atoms, in which, in addition, one or more H atoms may be replaced by D or F; two or more substituents R 2 here may be linked to one another and may form a ring;