A conjugated polymer selected from the following formulae *-[(Ar 1 -U-Ar 2) x -(Ar 3) y] n -* IVa *-[(Ar 1 -U-Ar 2) x -(Ar 3 -Ar 3) y] n -* IVb *-[(Ar 1 -U-Ar 2) x -(Ar 3 -Ar 3 -Ar 3) y] n -* IVc *-[(Ar 1) a - b -(Ar 2) c -(Ar 3) d] n -* IVd *-([(Ar 1) a - b -(Ar 2) c -(Ar 3) d] x -[(Ar 1) a -(A c) b -(Ar 2) c -(Ar 3) d] y) n -* IVe *-[(U-Ar 1 -U) x -(Ar 2 -Ar 3) y] n -* IVf *-[(U-Ar 1 -U) x -(Ar 2 -Ar 3 -Ar 2) y] n -* IVg *-[ b -(Ar 1) a - b -(Ar 2) c] n -* IVh *-([ b -(Ar 1) a - b -(Ar 2) c] x -[(A c) b -(Ar 1) a -(A c) b -(Ar 2) d] y) n -* IVi *-[(U-Ar 1) x -(U-Ar 2) y -(U-Ar 3) z] n -* IVk wherein U is a unit selected from the following subformulae and wherein the other individual radicals have the following meanings: X and Y are independently of each other, and on each occurrence identically or differently, C(R 1 R 2), C=C(R 1 R 2), or C(=O), R 1 and R 2 are independently of each other H, straight-chain, branched or cyclic alkyl with 1 to 30 C atoms, in which one or more CH 2 groups are optionally replaced by -O-, -S-, -C(=O)-,-C(=S)-, -C(=O)-O-, -O-C(=O)-, -NR 0 -, -SiR 0 R 00 -, -CF 2 -,-CHR 0 =CR 00 -, -CY 1 =CY 2 - or -C≡C- in such a manner that O and/or S atoms are not linked directly to one another, and in which one or more H atoms are optionally replaced by F, Cl, Br, I or CN, or denote aryl, heteroaryl, aryloxy or heteroaryloxy with 4 to 20 ring atoms which is optionally substituted, preferably by halogen or by one or more of the aforementioned alkyl or cyclic alkyl groups, Y 1 and Y 2 are independently of each other H, F, Cl or CN, Ar 1, Ar 2, Ar 3 are, on each occurrence identically or differently, and independently of each other, aryl or heteroaryl that is different from U, preferably has 5 to 30 ring atoms and is optionally substituted, preferably by one or more groups R S, A c is an aryl or heteroaryl group that is different from U and Ar 1-3, has 5 to 30 ring atoms, is optionally substituted by one or more groups R S, and is selected from aryl or heteroaryl groups having electron acceptor properties, R S is on each occurrence identically or differently F, Br, Cl,-CN, -NC, -NCO, -NCS, -OCN, -SCN, -C NR 0 R 00,-C X 0, -C R 0, -NH 2, -NR 0 R 00, -SH, -SR 0, -SO 3 H,-SO 2 R 0, -OH, -NO 2, -CF 3, -SF 5, optionally substituted silyl, carbyl or hydrocarbyl with 1 to 40 C atoms that is optionally substituted and optionally comprises one or more hetero atoms, R 0 and R 00 are independently of each other H or optionally substituted C 1-40 carbyl or hydrocarbyl, X 0 is halogen, preferably F, Cl or Br, a, b, c are on each occurrence identically or differently 0, 1 or 2, d is on each occurrence identically or differently 0 or an integer from 1 to 10, n is an integer >1, x is > 0 and ≤ 1, y is ≥ 0 and < 1, z is ≥ 0 and < 1, x+y+z is 1, and wherein these polymers can be alternating or random copolymers, and wherein in formula IVd and IVe in at least one of the repeating units [(Ar 1) a - b -(Ar 2) c -(Ar 3) d] and in at least one of the repeating units [(Ar 1) a -(A c) b -(Ar 2) c -(Ar 3) d] b is at least 1 and wherein in formula IVh and IVi in at least one of the repeating units [ b -(Ar 1) a - b -(Ar 2) d] and in at least one of the repeating units [ b -(Ar 1) a - b -(Ar 2) d] b is at least 1. X and Y are independently of each other, and on each occurrence identically or differently, C(R 1 R 2), C=C(R 1 R 2), or C(=O), R 1 and R 2 are independently of each other H, straight-chain, branched or cyclic alkyl with 1 to 30 C atoms, in which one or more CH 2 groups are optionally replaced by -O-, -S-, -C(=O)-,-C(=S)-, -C(=O)-O-, -O-C(=O)-, -NR 0 -, -SiR 0 R 00 -, -CF 2 -,-CHR 0 =CR 00 -, -CY 1 =CY 2 - or -C≡C- in such a manner that O and/or S atoms are not linked directly to one another, and in which one or more H atoms are optionally replaced by F, Cl, Br, I or CN, or denote aryl, heteroaryl, aryloxy or heteroaryloxy with 4 to 20 ring atoms which is optionally substituted, preferably by halogen or by one or more of the aforementioned alkyl or cyclic alkyl groups, Y 1 and Y 2 are independently of each other H, F, Cl or CN, Ar 1, Ar 2, Ar 3 are, on each occurrence identically or differently, and independently of each other, aryl or heteroaryl that is different from U, preferably has 5 to 30 ring atoms and is optionally substituted, preferably by one or more groups R S, A c is an aryl or heteroaryl group that is different from U and Ar 1-3, has 5 to 30 ring atoms, is optionally substituted by one or more groups R S, and is selected from aryl or heteroaryl groups having electron acceptor properties, R S is on each occurrence identically or differently F, Br, Cl,-CN, -NC, -NCO, -NCS, -OCN, -SCN, -C NR 0 R 00,-C X 0, -C R 0, -NH 2, -NR 0 R 00, -SH, -SR 0, -SO 3 H,-SO 2 R 0, -OH, -NO 2, -CF 3, -SF 5, optionally substituted silyl, carbyl or hydrocarbyl with 1 to 40 C atoms that is optionally substituted and optionally comprises one or more hetero atoms, R 0 and R 00 are independently of each other H or optionally substituted C 1-40 carbyl or hydrocarbyl, X 0 is halogen, preferably F, Cl or Br, a, b, c are on each occurrence identically or differently 0, 1 or 2, d is on each occurrence identically or differently 0 or an integer from 1 to 10, n is an integer >1, x is > 0 and ≤ 1, y is ≥ 0 and < 1, z is ≥ 0 and < 1, x+y+z is 1, and