Compound comprising at least one structure of the formula: where the following applies to the symbols used: X 1, X 2, X 3, X 4, X 5, X 6, X 7, X 8, X 9, X 10, X 11, X 12, X 13, X 14, X 15, X 16 are CR 1; Ar is selected on each occurrence, identically or differently, from one of the formulae (R 1 -1) to (R 1 -95) where the following applies to the symbols used: Y is O, S or NR 2, preferably O or S; i is on each occurrence, independently, 0, 1 or 2; j is on each occurrence, independently, 0, 1, 2 or 3; h is on each occurrence, independently, 0, 1, 2, 3 or 4; g is on each occurrence, independently, 0, 1, 2, 3, 4 or 5; and the dashed bond marks the bonding position; R 1 is selected on each occurrence, identically or differently, from the group consisting of H, D, F, CN, N(Ar 1) 2, a straight-chain alkyl group having 1 to 8 C atoms, or a branched or cyclic alkyl group having 3 to 8 C atoms, or an alkenyl group having 2 to 8 C atoms, which may in each case be substituted by one or more radicals R 2, or an aromatic or heteroaromatic ring system having 6 to 24 aromatic ring atoms, which may in each case be substituted by one or more non-aromatic radicals R 1; Ar 1 is, identically or differently on each occurrence, an aromatic or heteroaromatic ring system having 5 to 40 aromatic ring atoms, which may in each case be substituted by one or more radicals R 2; R 2 is selected on each occurrence, identically or differently, from the group consisting of H, D, an aliphatic hydrocarbon radical having 1 to 10 C atoms, or an aromatic or heteroaromatic ring system having 5 to 30 aromatic ring atoms, which may be substituted by one or more alkyl groups having in each case 1 to 4 carbon atoms; where in formula at most 2 of the symbols X 1, X 2, X 3, X 4, X 5, X 6, X 7, X 8, X 9, X 10, X 11, X 12, X 13, X 14, X 15, X 16 are not equal to CH or CD. X 1, X 2, X 3, X 4, X 5, X 6, X 7, X 8, X 9, X 10, X 11, X 12, X 13, X 14, X 15, X 16 are CR 1; Ar is selected on each occurrence, identically or differently, from one of the formulae (R 1 -1) to (R 1 -95) Y is O, S or NR 2, preferably O or S; i is on each occurrence, independently, 0, 1 or 2; j is on each occurrence, independently, 0, 1, 2 or 3; h is on each occurrence, independently, 0, 1, 2, 3 or 4; g is on each occurrence, independently, 0, 1, 2, 3, 4 or 5; and R 1 is selected on each occurrence, identically or differently, from the group consisting of H, D, F, CN, N(Ar 1) 2, a straight-chain alkyl group having 1 to 8 C atoms, or a branched or cyclic alkyl group having 3 to 8 C atoms, or an alkenyl group having 2 to 8 C atoms, which may in each case be substituted by one or more radicals R 2, or an aromatic or heteroaromatic ring system having 6 to 24 aromatic ring atoms, which may in each case be substituted by one or more non-aromatic radicals R 1; Ar 1 is, identically or differently on each occurrence, an aromatic or heteroaromatic ring system having 5 to 40 aromatic ring atoms, which may in each case be substituted by one or more radicals R 2; R 2 is selected on each occurrence, identically or differently, from the group consisting of H, D, an aliphatic hydrocarbon radical having 1 to 10 C atoms, or an aromatic or heteroaromatic ring system having 5 to 30 aromatic ring atoms, which may be substituted by one or more alkyl groups having in each case 1 to 4 carbon atoms;