Organic electroluminescent device, comprising at least one organic layer which comprises at least one aromatic boronic acid derivative, where the boron atom is trisubstituted and the boronic acid derivative is a cyclic boronic acid anhydride, a boronic acid ester, a boronic acid amide or a boronic acid amidoester, characterised in that the boronic acid derivative has a structure of the formula, where the following applies to the symbols used: Ar is on each occurrence, identically or differently, an aromatic or heteroaromatic ring system having 5 to 40 aromatic ring atoms, which may be substituted by one or more radicals R 1; B stands on each occurrence for a boron atom; X is on each occurrence, identically or differently, a group OR 2, or N(R 2) 2; Y is on each occurrence, identically or differently, X; R 1 is on each occurrence, identically or differently, F, Cl, Br, I, CN, a straight-chain alkyl, alkoxy or thioalkoxy chain having 1 to 40 C atoms or a branched or cyclic alkyl, alkoxy or thioalkoxy chain having 3 to 40 C atoms, each of which may be substituted by R 3 and in which one or more non-adjacent C atoms may be replaced by N-R 3, O, S, CO, O-CO-O, CO-O, -CR 3 =CR 3 - or -C≡C- and in which, in addition, one or more H atoms may be replaced by F, Cl, Br, I or CN, or an aromatic or heteroaromatic ring system having 5 to 40 aromatic ring atoms, which may also be substituted by one or more radicals R 3 or a combination of two, three or four of these systems; two or more radicals R 1 here may also form a mono- or polycyclic, aliphatic or aromatic ring system with one another; R 2 is on each occurrence, identically or differently, a straight-chain alkyl chain having 1 to 40 C atoms or a branched or cyclic alkyl chain having 3 to 40 C atoms, each of which may be substituted by R 3 and in which, in addition, one or more non-adjacent C atoms may be replaced by N-R 3, O, S, CO, O-CO-O, CO-O, -CR 3 =CR 3 - or -C≡C-, with the proviso that a heteroatom is not bonded directly to the oxygen or sulfur or nitrogen of the group X or Y, and in which one or more H atoms may be replaced by F, Cl, Br, I or CN, or an aromatic or heteroaromatic ring system having 5 to 40 aromatic ring atoms, which may also be substituted by one or more radicals R 3, or a combination of two, three or four of these systems; two radicals R 2 here together with B, X and Y may form a mono- or polycyclic, aliphatic or aromatic ring system; R 3 is on each occurrence, identically or differently, H or an aliphatic or aromatic hydrocarbon radical having 1 to 20 C atoms; n is on each occurrence, identically or differently, 1, 2, 3, 4, 5 or 6. Ar is on each occurrence, identically or differently, an aromatic or heteroaromatic ring system having 5 to 40 aromatic ring atoms, which may be substituted by one or more radicals R 1; B stands on each occurrence for a boron atom; X is on each occurrence, identically or differently, a group OR 2, or N(R 2) 2; Y is on each occurrence, identically or differently, X; R 1 is on each occurrence, identically or differently, F, Cl, Br, I, CN, a straight-chain alkyl, alkoxy or thioalkoxy chain having 1 to 40 C atoms or a branched or cyclic alkyl, alkoxy or thioalkoxy chain having 3 to 40 C atoms, each of which may be substituted by R 3 and in which one or more non-adjacent C atoms may be replaced by N-R 3, O, S, CO, O-CO-O, CO-O, -CR 3 =CR 3 - or -C≡C- and in which, in addition, one or more H atoms may be replaced by F, Cl, Br, I or CN, or an aromatic or heteroaromatic ring system having 5 to 40 aromatic ring atoms, which may also be substituted by one or more radicals R 3 or a combination of two, three or four of these systems; two or more radicals R 1 here may also form a mono- or polycyclic, aliphatic or aromatic ring system with one another; R 2 is on each occurrence, identically or differently, a straight-chain alkyl chain having 1 to 40 C atoms or a branched or cyclic alkyl chain having 3 to 40 C atoms, each of which may be substituted by R 3 and in which, in addition, one or more non-adjacent C atoms may be replaced by N-R 3, O, S, CO, O-CO-O, CO-O, -CR 3 =CR 3 - or -C≡C-, with the proviso that a heteroatom is not bonded directly to the oxygen or sulfur or nitrogen of the group X or Y, and in which one or more H atoms may be replaced by F, Cl, Br, I or CN, or an aromatic or heteroaromatic ring system having 5 to 40 aromatic ring atoms, which may also be substituted by one or more radicals R 3, or a combination of two, three or four of these systems; two radicals R 2 here together with B, X and Y may form a mono- or polycyclic, aliphatic or aromatic ring system; R 3 is on each occurrence, identically or differently, H or an aliphatic or aromatic hydrocarbon radical having 1 to 20 C atoms; n is on each occurrence, identically or differently, 1, 2, 3, 4, 5 or 6.