Conjugated polymers, their preparation and use thereof

A polymer comprising at least 5 mol % of units of the formula (1),

• where the symbols used have the following meanings:
• X is identical or different on each occurrence and is in each case CR2, N(R1), —CR2—CR2— or —N(R1)—CR2—;
• Z is identical or different on each occurrence and is in each case CR or N;
• R is identical or different on each occurrence and is in each case H, a linear, branched or cyclic alkyl or alkoxy chain which has from 1 to 22 carbon atoms and in which one or more nonadjacent carbon atoms may also be replaced by N(R1)—, —O—, —S—, —O—CO—O—, —CO—O—, C═O, —C(R1)═C(R1)— or —C≡C—, where one or more H atoms may also be replaced by fluorine or an aromatic radical R1, an aromatic or heteroaromatic ring system or an aryloxy group having from 5 to 40 carbon atoms, in which one or more carbon atoms may also be replaced by O, S or N and which may also be substituted by one or more nonaromatic radicals R, where two or more of the radicals R may together also form an aromatic or aliphatic, monocyclic or polycyclic ring system, or fluorine, chlorine, CN, N(R1)2, Si(R1)3 or B(R1)2;
• R1 is identical or different on each occurrence and is in each case H, a linear, branched or cyclic alkyl chain which has from 1 to 22 carbon atoms and in which one or more nonadjacent carbon atoms may also be replaced by O, S, —CO—O—, —O—CO—O—, C═O, —CH═CH— or —C≡C—, where one or more H atoms may also be replaced by fluorine, an aryl, heteroaryl or aryloxy group which has from 5 to 40 carbon atoms and in which one or more carbon atoms may also be replaced by O, S or N, which may also be substituted by one or more nonaromatic radicals R1, where one or more radicals R1 or R1 and further radicals R may together also form an aromatic or aliphatic, monocyclic or polycyclic ring system;
• n is identical or different on each occurrence and is in each case 0 or 1;
• characterized in that the polymer further comprises at least 0.01 mol %, of units of the formula (2),
• where the symbols and indices have the following meanings:
• A is identical or different on each occurrence and is in each case S, O or N(R1);
• Z is identical or different on each occurrence and is in each case CR or N, with the proviso that the central unit (II) is not a quinoxaline, not a benzothiadiazole and not an unsubstituted anthracene and with the further proviso that at least one radical R is not hydrogen;
• m is identical or different on each occurrence and is in each case 1, 2 or 3;
• the further symbols are as described under the formula (1);
• and the broken-line bond in formula (1) and formula (2) as in all further formulae indicates the linkage in the polymer.