A blend containing an n-type organic semiconducting compound which does not contain a fullerene moiety, and further containing a p-type OSC compound which is a conjugated copolymer comprising donor and acceptor units that are distributed in random sequence along the polymer backbone wherein the n-type OSC compound is of formula NI wherein the individual radicals, independently of each other and on each occurrence identically or differently, have the following meanings Ar 1 wherein a group is not adjacent to another group Ar 2 Ar 3 Ar 4,5 arylene or heteroarylene that has from 5 to 20 ring atoms, is mono- or polycyclic, optionally contains fused rings, and is unsubstituted or substituted by one or more identical or different groups R 1 or L, or CY 1 =CY 2 or -C≡C-, U 1 CR 1 R 2, SiR 1 R 2, GeR 1 R 2, NR 1 or C=O, V 1 CR 3 or N, W 1 S, O, Se or C=O, R 1-3, 5-7 Z 1, H, F, Cl, CN, or 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 -, -CR 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, and in which one or more CH 2 or CH 3 groups are optionally replaced by a cationic or anionic group, or aryl, heteroaryl, arylalkyl, heteroarylalkyl, aryloxy or heteroaryloxy, wherein each of the aforementioned cyclic groups has 5 to 20 ring atoms, is mono- or polycyclic, does optionally contain fused rings, and is unsubstituted or substituted by one or more identical or different groups L, and the pair of R 1 and R 2 together with the C, Si or Ge atom to which they are attached, may also form a spiro group with 5 to 20 ring atoms which is mono- or polycyclic, does optionally contain fused rings, and is unsubstituted or substituted by one or more identical or different groups L, Z 1 an electron withdrawing group, R T1,T2 H, a carbyl or hydrocarbyl group with 1 to 30 C atoms that is optionally substituted by one or more groups L and optionally comprises one or more hetero atoms, wherein at least one of R T1 and R T2 is an electron withdrawing group, Y 1,2 H, F, Cl or CN, L F, Cl, -NO 2, -CN, -NC, -NCO, -NCS, -OCN, -SCN, R 0, OR 0, SR 0, -C(=O)X 0, -C(=O)R 0, -C(=O)-OR 0, -O-C(=O)-R 0, -NH 2,-NHR 0, -NR 0 R 00, -C(=O)NHR 0, -C(=O)NR 0 R 00, -SO 3 R 0,-SO 2 R 0, -OH, -NO 2, -CF 3, -SF 5, or optionally substituted silyl, or carbyl or hydrocarbyl with 1 to 30 C atoms that is optionally substituted and optionally comprises one or more hetero atoms, preferably F, Cl, -CN, R 0, -OR 0, -SR 0, -C(=O)-R 0, -C(=O)-OR 0, -O-C(=O)-R 0, -O-C(=O)-OR 0, -C(=O)-NHR 0, or -C(=O)-NR 0 R 00, R 0, R 00 H or straight-chain or branched alkyl with 1 to 20 C atoms that is optionally fluorinated, X 0 halogen, a, b, c 0, 1, 2 or 3, i 0, 1, 2 or 3, k 0 or an integer from 1 to 10, m 0 or an integer from 1 to 10. Ar 1 wherein a group is not adjacent to another group Ar 2 Ar 3 Ar 4,5 arylene or heteroarylene that has from 5 to 20 ring atoms, is mono- or polycyclic, optionally contains fused rings, and is unsubstituted or substituted by one or more identical or different groups R 1 or L, or CY 1 =CY 2 or -C≡C-, U 1 CR 1 R 2, SiR 1 R 2, GeR 1 R 2, NR 1 or C=O, V 1 CR 3 or N, W 1 S, O, Se or C=O, R 1-3, 5-7 Z 1, H, F, Cl, CN, or 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 -, -CR 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, and in which one or more CH 2 or CH 3 groups are optionally replaced by a cationic or anionic group, or aryl, heteroaryl, arylalkyl, heteroarylalkyl, aryloxy or heteroaryloxy, wherein each of the aforementioned cyclic groups has 5 to 20 ring atoms, is mono- or polycyclic, does optionally contain fused rings, and is unsubstituted or substituted by one or more identical or different groups L, and the pair of R 1 and R 2 together with the C, Si or Ge atom to which they are attached, may also form a spiro group with 5 to 20 ring atoms which is mono- or polycyclic, does optionally contain fused rings, and is unsubstituted or substituted by one or more identical or different groups L, Z 1 an electron withdrawing group, R T1,T2 H, a carbyl or hydrocarbyl group with 1 to 30 C atoms that is optionally substituted by one or more groups L and optionally comprises one or more hetero atoms, wherein at least one of R T1 and R T2 is an electron withdrawing group, Y 1,2 H, F, Cl or CN, L F, Cl, -NO 2, -CN, -NC, -NCO, -NCS, -OCN, -SCN, R 0, OR 0, SR 0, -C(=O)X 0, -C(=O)R 0, -C(=O)-OR 0, -O-C(=O)-R 0, -NH 2,-NHR 0, -NR 0 R 00, -C(=O)NHR 0, -C(=O)NR 0 R 00, -SO 3 R 0,-SO 2 R 0, -OH, -NO 2, -CF 3, -SF 5, or optionally substituted silyl, or carbyl or hydrocarbyl with 1 to 30 C atoms that is optionally substituted and optionally comprises one or more hetero atoms, preferably F, Cl, -CN, R 0, -OR 0, -SR 0, -C(=O)-R 0, -C(=O)-OR 0, -O-C(=O)-R 0, -O-C(=O)-OR 0, -C(=O)-NHR 0, or -C(=O)-NR 0 R 00, R 0, R 00 H or straight-chain or branched alkyl with 1 to 20 C atoms that is optionally fluorinated, X 0 halogen, a, b, c 0, 1, 2 or 3, i 0, 1, 2 or 3, k 0 or an integer from 1 to 10, m 0 or an integer from 1 to 10.