Electroluminescent polymers and use thereof

A polymer containing units of the formula (I)

• in which
• R is on each occurrence, identically or differently, H, a straight-chain alkyl chain having 1 to 40 C atoms, a branched alkyl chain having 3 to 40 C atoms or a cyclic alkyl chain having 3 to 40 C atoms, each of which is optionally substituted by R1 and in which, in addition, one or more non-adjacent C atoms is optionally replaced by ═N—R1, —O—, —S—, —O—CO—O—, —CO—O—, —CR1═CR1— or —C≡C— and in which, in addition, one or more H atoms is optionally replaced by F, Cl, Br, I or CN, or an aromatic ring system having 5 to 40 C atoms or a heteroaromatic ring system having 2 to 40 C atoms, which is optionally substituted by one or more radicals R1;
• the two radicals R here optionally form a further mono- or polycyclic, aromatic or aliphatic ring system with one another;
• R1 is on each occurrence, identically or differently, H, a straight-chain alkyl chain having 1 to 22 C atoms, a branched alkyl chain having 3 to 22 C atoms or a cyclic alkyl chain having 3 to 22 C atoms, in which, in addition, one or more non-adjacent C atoms is optionally replaced by ═N—R2, —O—, —S—, —O—CO—O—, —CO—O—, —CR2═CR2— or —C≡C— and in which, in addition, one or more H atoms is optionally replaced by F, Cl, Br, I or CN, or an aryl, heteroaryl, aryloxy or heteroaryloxy group having 5 to 40 C atoms, which is optionally substituted by one or more non-aromatic radicals R1;
• two or more of the radicals R1 here optionally form a ring system with one another and/or with R;
• or F, Cl, Br, I, CN, N(R2)2, Si(R2)3 or B(R2)2;
• R2 is on each occurrence, identically or differently, H or an aliphatic or aromatic hydrocarbon radical having 1 to 20 C atoms;
• X is on each occurrence, identically or differently, B, C, N, O, P, S, Se, P═O, S═O or SO2;
• n is on each occurrence, identically or differently, 0, 1, 2 or 3;
• m is on each occurrence, identically or differently, 0, 1 or 2;
• and
• the dashed bond denotes the link in the polymer and with the proviso that
• if X is O then there are no Rs present and if X is N or B, then there is only one R present and if X is S or P═O then there can be no Rs present.