TECHNOLOGY FOCUS - POLYMERS - Preferred Components: Units of formula (I) are represented by formulae (Ia), (Ib), or (Ic). Compound of formula (I) is a polymer containing greater than or equal to 1 units of formula -((Ar 1) a(U) b(Ar 2) c(Ar 3) d)- (II) and greater than or equal to 1 units of formula -((Ar 1) a(D) b(Ar 2) c(Ar 3) d)- (III). Polymer is represented by formula asterisk-((A) x(B') y) n-asterisk (IV) e.g. formulae asterisk-((Ar 1UAr 2) x-(Ar 3) y) n-asterisk (IVa), asterisk-((Ar 1UAr 2) x-(Ar 3Ar 3) y) n-asterisk (IVb), asterisk-((Ar 1UAr 2) x-(Ar 3Ar 3Ar 3) y) n-asterisk (IVc), asterisk-((Ar 1) a(U) b(Ar 2) c(Ar 3) d) n-asterisk (IVd), or asterisk-(((Ar 1) a(U) b(Ar 2) c(Ar 3) d) x-((Ar 1) a(D) b(Ar 2) c(Ar 3) d) y) n-asterisk (IVe) which can be alternating or random copolymers. Polymer is represented by formula R 5-chain-R 6(V). Polymer is represented by formulae (IV1)-(IV10). Compound is represented by formulae (VI1)-(VI3). Compound is represented by formulae (VII1)-(VII4). Mixture or polymer blend contains greater than or equal to 1 n-type organic semiconductor compounds e.g. (substituted) fullerene.A=formula (I);X 0=F, Cl, or Br;a-c=0, 1, or 2 provided that b is greater than or equal to 1;d=1-10;D=5-30C aryl or heteroaryl other than U and Ar 1-Ar 3optionally substituted by RS;B'=unit other than A and contains greater than or equal to 1 optionally substituted aryl or heteroaryl groups, preferably formula (III);x, y=0-1;x+y=1;n= greater than or equal to 1;chain=formulae (IV) or (IVa)-(IVe);R 5, R 6=H, F, Br, Cl, I, -CH 2Cl, -CHO, -CR'=CR'' 2, -SiR'R''R''', -SiR'X'X'', -SiR'R''X', -SnR'R''R''', -BR'R'', -B(OR')(OR''), -B(OH 2), O, SO 2R', -CCH, -CCSiR' 3, -ZnX', P'-Sp-, or endcap group;X', X''=halo;R', R'', R'''=R 0;R'+R'', R'+R''', R''+R'''=ring;E=optionally substituted 3-30C aryl or heteroaryl, CY 1=CY 2, or -CC-;p=0, 1, 2, 3, or 4;X=O, S, or Se; andR=R 7. Preferred Definitions:    X 1-X 4=S;    G 1, G 2=-CN, -C(O)ORA, -C(O)RA, -C(O)N(RA-RB), 1-20C perfluoroalkyl, -SO 3RA, or -NO;    RA, RB=H, 1-20C alkyl, 3-30C cyclic alkyl provided that greater than or equal to 1 H are optionally substituted by F, or optionally substituted 4-20C aryl, heteroaryl, aryloxy, or heteroaryloxy;    R 1, R 2=1-30C (cyclic) alkyl optionally substituted by F;    R 0, R 00=H or optionally substituted 1-40C carbyl or hydrocarbyl;    Ar 1-Ar 2=formulae (D1)-(D94);    X 11, X 12=S provided that the other is Se;    R 11-R 18=H or R 1;    Ar 3=formulae (A1)-(A44); and    R 5, R 6=halo, stannyl, or boronate.