NOVELTY - Polymer comprising at least one repeating unit of substituted diketopyrrolopyrrole moiety, is new.    USE - The polymer is useful in an organic semiconductor material, which is used in a semiconductor device including an organic photovoltaic device (solar cell), photodiode, or organic field effect transistor (all claimed).    ADVANTAGE - The polymer: exhibits excellent solubility in organic solvents; excellent film-forming properties; exhibits high efficiency of energy conversion; exhibits excellent field-effect mobility; and provides the device with good on/off current ratios and/or excellent stability.    DETAILED DESCRIPTION - Polymer comprising at least one repeating unit of substituted diketopyrrolopyrrole moiety of formula (-A-D-) (I), ((-A-D-)x-(B1-D-)y) (II) or ((-A-D-)r-(B1-D-)s-(A-E-)t-(B1-E-)u-) (III), is new.    x, r, t = 0.995-0.005;    y, s, u = 0.005-0.995;    x+y = 1;    r+s+t+u = 1;    A = substituted diketopyrrolopyrrole moiety; and    B1, D, E = e.g. substituted benzo(1,2-b;4,5-b')dithiophene moiety, substituted 2,3-dihydro-1,6-dithia-dicyclopenta(b,g)naphthalene moiety, substituted 3,8-dithia-dicyclopenta(a,f)naphthalene moiety, substituted 1,6-dithia-dicyclopenta(a,f)naphthalene moiety, substituted 9H-carbazole moiety, substituted 9H-fluorene moiety, substituted toluene moiety, substituted naphthalene moiety, substituted dithiophenyl moiety, benzo(1,2,5)thiadiazole moiety, substituted thiophenyl moieties, substituted pyrene moiety, substituted pyrene moiety and substituted diketopyrrolopyrrole moiety.    With provisos Full definitions are given in the DEFINITIONS (Full Definitions) Field. INDEPENDENT CLAIMS are also included or:    (1) an organic semiconductor material, layer or component, comprising the polymer;    (2) a semiconductor device, comprising the polymer or the organic semiconductor material, layer or component;    (3) substituted 2,5-dihydro-pyrrolo(3,4-c)pyrrole-1,4-dione compounds of formula (VI); and    (4) preparing the organic semiconductor device, comprising applying a solution and/or dispersion of the polymer in an organic solvent to a suitable substrate and removing the solvent.    X11 = ZnX12, -SnR207R208R209;    R207, R208, R209 = H or 1-6C alkyl, where two radicals optionally form a common ring and these radicals are optionally branched;    X12 = halo, (preferably I, or Br), -OS(O)2CF3, -OS(O)2-aryl, preferably 4-methyl benzene sulfonyl, -OS(O)2CH3, -B(OH)2, -B(OH)3-, -BF3, -B(OY1)2, 2-methyl-benzo(1,3,2)dioxa-borole moiety of formula (VIa) or dioxa-borane moiety of formula (VIb);    Y2 = 2-10C alkylene -CY3Y4-CY5Y6 or -CY7Y8-CY9Y10-CY11Y12-;    Y3-Y11 = H, or 1-10C alkyl, preferably -C(CH3)2C(CH3)2-, -C(CH3)2CH2C(CH3)2- or -CH2C(CH3)2 CH2-;    Y13, Y14 = H or 1-10C alkyl; and    Y1 = 1-10C alkyl.