Electronic device, comprising anode, cathode and at least one organic layer, which comprises at least one compound of the formula (I-a) or where a group selected from the groups of the formulae where: E is selected on each occurrence, identically or differently, from a single bond, C(R 1) 2, Si(R 1) 2, C=O, O, S, S=O SO 2; Z is on each occurrence, identically or differently, CR 1 or N; W is selected on each occurrence, identically or differently, from C=O, O, S, S=O, SO 2 and NR 1; Ar 1 is selected on each occurrence, identically or differently, from aryl or heteroaryl groups having 6 to 13 aromatic ring atoms, which may be substituted by one or more radicals R 1; Ar 2 is selected on each occurrence, identically or differently, from aryl or heteroaryl groups having 6 to 13 aromatic ring atoms, which may be substituted by one or more radicals R 1; Y is a single bond; 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, 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 having 3 to 20 C atoms or an alkenyl or alkynyl group having 2 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=S, C=NR 2, -C(=O)O-, -C(=O)NR 2 -, NR 2, P(=O)(R 2), -O-, -S-, SO or SO 2 and where one or more H atoms in the above-mentioned groups may be replaced by D, F or CN, or an aromatic or heteroaromatic ring system having 5 to 30 aromatic ring atoms, which may be substituted by one or more radicals R 2, or an aryloxy or heteroaryloxy group having 5 to 30 aromatic ring atoms, which may be substituted by one or more radicals R 2; 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 may be linked to one another and form a ring; n is on each occurrence, identically or differently, 0, 1, 2, 3 or 4; i is equal to 0; k is on each occurrence, identically or differently, 0 or 1, where at least one index k per group of the formula (C-1) must be equal to 1; is bonded at the positions denoted by *, and where a group selected from groups of the formulae (A-1) and (A-2) must be bonded at at least one of the positions denoted by *, and where furthermore no condensed aryl or heteroaryl group having 14 or more aromatic ring atoms is present in the compound; or which comprises at least one compound of the formula (I-c) where R 1 is as defined above, where the compound may be substituted at all free positions by radicals R 1, where a group selected from the groups of the formulae (A-1), (A-2), and (C-2) is in each case bonded at the positions denoted by *, and where the groups at the two positions denoted by * in formula (I-c) are selected in accordance with one of the following embodiments (I-c-3), (I-c-4), (I-c-6) and (I-c-7): Embodiment Group in position * on the left Group in position * on the right formula (I-c-3) formula (A-1) formula (C-1) formula (I-c-4) formula (A-1) formula (C-2) formula (I-c-6) formula (A-2) formula (C-1) formula (I-c-7) formula (A-2) formula (C-2) E is selected on each occurrence, identically or differently, from a single bond, C(R 1) 2, Si(R 1) 2, C=O, O, S, S=O SO 2; Z is on each occurrence, identically or differently, CR 1 or N; W is selected on each occurrence, identically or differently, from C=O, O, S, S=O, SO 2 and NR 1; Ar 1 is selected on each occurrence, identically or differently, from aryl or heteroaryl groups having 6 to 13 aromatic ring atoms, which may be substituted by one or more radicals R 1; Ar 2 is selected on each occurrence, identically or differently, from aryl or heteroaryl groups having 6 to 13 aromatic ring atoms, which may be substituted by one or more radicals R 1; Y is a single bond; 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, 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 having 3 to 20 C atoms or an alkenyl or alkynyl group having 2 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=S, C=NR 2, -C(=O)O-, -C(=O)NR 2 -, NR 2, P(=O)(R 2), -O-, -S-, SO or SO 2 and where one or more H atoms in the above-mentioned groups may be replaced by D, F or CN, or an aromatic or heteroaromatic ring system having 5 to 30 aromatic ring atoms, which may be substituted by one or more radicals R 2, or an aryloxy or heteroaryloxy group having 5 to 30 aromatic ring atoms, which may be substituted by one or more radicals R 2; 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 may be linked to one another and form a ring; n is on each occurrence, identically or differently, 0, 1, 2, 3 or 4; i is equal to 0; k is on each occurrence, identically or differently, 0 or 1, where at least one index k per group of the formula (C-1) must be equal to 1;