NOVELTY - A polymer (P1) comprising diketopyrrolopyrrole repeating units is new.    USE - For producing the organic semiconductor material, for forming layer or components for semiconductor devices selected from photovoltaic (PV) devices, photodiodes, or organic field effect transistors (all claimed), or for solar cells.    ADVANTAGE - The polymers have excellent solubility in organic solvents, excellent film-forming properties, high efficiency of energy conservation, field-effect mobility, good on/off current ratios, and excellent stability.    DETAILED DESCRIPTION - A polymer (P1) comprising diketopyrrolopyrrole and thiophene units selected from at least one repeating unit of formula -(A1-D1)-, and at least one repeating unit selected from -(B1-D1)-, -(A1-E1)-, and -(B1-E1)-; or having diketopyrrolopyrrole repeating units of formula (iii) or (iv), is new.    Ar23=group of formula (vii) or -Ar25-Ar26-Ar27-(Ar28-Ar29)s- (viii);    Ar30=group of formula (ix) or Ar38-Ar33-Ar34-Ar35-(Ar36-Ar37)y-Ar39 (x);    Ar26 and Ar26a=4-18C alkyl;    A1=group of formula (i), (v) or (vi);    a, b, p, or q=0-2;    s, t y and w=0 or 1;    u or v=1 or 2;    Ar1, Ar2, Ar21, Ar21a, Ar24, Ar24a, Ar25, Ar27, Ar29, Ar31, Ar31a, Ar34, Ar36, Ar38, and Ar39=thiophene-2,5-diyl or a group of formula (xi);    Ar3 and Ar3a=thiophene-2,5-diyl, or a group of formula selected from (xi)-(xiii);    Ar2, Ar2a, Ar22, Ar22a, Ar26, Ar28, Ar32, Ar32a, Ar33, Ar35, and Ar37=group of formula (xii) or (xiii);    X1 and X2=N or CH;    X3 and X4=N or CR3a;    R1, R2, R24 and R25=H, 1-100C alkyl (preferably 6-24C alkyl, 6-24C aryl, especially phenyl or 1- or 2-naphthyl (both optionally mono- to tri-substituted by 1-8C alkyl, 1-8C thioalkoxy, 1-8C alkoxy, or pentafluorophenyl));    R3 and R3a=1-25C alkyl (preferably 4-25C alkyl (optionally interrupted by at least one O);    B1, D1 and E1=group of formula (i), (ii), or -(Ar4)k-(Ar5)l-(Ar6)r-(Ar7)z- (xiv);    k=1;    l, r and z=0 or 1;    Ar4-Ar7=group of formula selected from (xv)-(xviii), or thiazolo(5,4-d)thiazol-2,5-diyl;    X5 and X6=N or CR14;    c and c1=1-3;    Ar8 and Ar8a=thiophene-2,5-diyl or a group of formula (xi);    R1a and R2a=H, 1-36C alkyl (preferably 6-24C alkyl), 6-24C aryl (preferably phenyl or 1- or 2-naphthyl (all optionally mono- to tri-substituted by 1-8C alkyl, 1-8C thioalkoxy, 1-8C alkoxy, or pentafluorophenyl));    R14, R14a, R17 and R17a=H, or 1-25 alkyl (preferably 6-25C alkyl (optionally interrupted by at least one O)).    Provided that:    (1) one of X1 and X2 is N and the other is CH;    (2) one of X3 and X4 is N and the other is CR3a;    (3) in case where B1, D1 and E1 are a group of formula (i), then they are different from A1; and    (4) one of X5 and X6 is N and the other is CR14.    INDEPENDENT CLAIMS are included for the following:    (1) an organic semiconductor material (M1), its layer or component, comprising the polymer (P1);    (2) a semiconductor device (S1) comprising the polymer (P1), or the organic semiconductor material (M1), its layer or component;    (3) preparation of the organic semiconductor device (S1) involving applying a solution and/or dispersion of the polymer (P1) in an organic solvent to a suitable substrate and removing the solvent; and    (4) preparation of the polymer (P1).