Compound of the formula, or, where the following applies to the symbols and indices used: Ar S stands on each occurrence, identically or differently, for an aromatic or heteroaromatic ring system having 5 to 25 aromatic ring atoms, which may in each case be substituted by one or more radicals R 1; X stands for CR 2, N; or X stands for C, if it is bonded to an adjacent group; R 0, R 1, R 2 stand on each occurrence, identically or differently, for H, D, F, a straight-chain alkyl, alkoxy or thioalkyl groups having 1 to 20 C atoms or branched or a cyclic alkyl, alkoxy or thioalkyl groups having 3 to 20 C atoms, each of which may be substituted by one or more radicals R, where one or more H atoms may be replaced by D or F, an aromatic or heteroaromatic ring systems having 5 to 30 aromatic ring atoms, which may in each case be substituted by one or more radicals R, where two radicals R 0 may form a ring system with one another, which may be substituted by one or more radicals R; R L stands on each occurrence, identically or differently, for H, D, F, a straight-chain alkyl group having 1 to 20 C atoms or branched or a cyclic alkyl group having 3 to 20 C atoms, each of which may be substituted by one or more radicals R, or an aromatic ring system having 5 to 25 aromatic ring atoms, which may in each case be substituted by one or more radicals R; R stands on each occurrence, identically or differently, for H, D, F, a straight-chain alkyl group having 1 to 10 C atoms or branched or cyclic alkyl group having 3 to 20 C atoms, each of which may be substituted by one or more radicals R', where one or more H atoms may be replaced by D or F, or an aromatic ring system having 6 to 18 aromatic ring atoms; Ar is an aromatic or heteroaromatic ring system having 5 to 24 aromatic ring atoms, which may in each case also be substituted by one or more radicals R'; R' stands on each occurrence, identically or differently, for H, D, F, a straight-chain alkyl group having 1 to 10 C atoms or branched or cyclic alkyl group having 3 to 10 C atoms, where one or more H atoms may be replaced by D or F, or an aromatic ring system having 5 to 18 C atoms; n, q, p are identically or differently an integer selected from 0 or 1; and r, s are identically or differently, equal to 0 or 1; with the proviso that r + s ≥ 1. Ar S stands on each occurrence, identically or differently, for an aromatic or heteroaromatic ring system having 5 to 25 aromatic ring atoms, which may in each case be substituted by one or more radicals R 1; X stands for CR 2, N; or X stands for C, if it is bonded to an adjacent group; R 0, R 1, R 2 stand on each occurrence, identically or differently, for H, D, F, a straight-chain alkyl, alkoxy or thioalkyl groups having 1 to 20 C atoms or branched or a cyclic alkyl, alkoxy or thioalkyl groups having 3 to 20 C atoms, each of which may be substituted by one or more radicals R, where one or more H atoms may be replaced by D or F, an aromatic or heteroaromatic ring systems having 5 to 30 aromatic ring atoms, which may in each case be substituted by one or more radicals R, where two radicals R 0 may form a ring system with one another, which may be substituted by one or more radicals R; R L stands on each occurrence, identically or differently, for H, D, F, a straight-chain alkyl group having 1 to 20 C atoms or branched or a cyclic alkyl group having 3 to 20 C atoms, each of which may be substituted by one or more radicals R, or an aromatic ring system having 5 to 25 aromatic ring atoms, which may in each case be substituted by one or more radicals R; R stands on each occurrence, identically or differently, for H, D, F, a straight-chain alkyl group having 1 to 10 C atoms or branched or cyclic alkyl group having 3 to 20 C atoms, each of which may be substituted by one or more radicals R', where one or more H atoms may be replaced by D or F, or an aromatic ring system having 6 to 18 aromatic ring atoms; Ar is an aromatic or heteroaromatic ring system having 5 to 24 aromatic ring atoms, which may in each case also be substituted by one or more radicals R'; R' stands on each occurrence, identically or differently, for H, D, F, a straight-chain alkyl group having 1 to 10 C atoms or branched or cyclic alkyl group having 3 to 10 C atoms, where one or more H atoms may be replaced by D or F, or an aromatic ring system having 5 to 18 C atoms; n, q, p are identically or differently an integer selected from 0 or 1; and r, s are identically or differently, equal to 0 or 1; with the proviso that r + s ≥ 1.