NOVELTY - A semiconductor device including diode, photodiode, organic FET, solar cell, or device containing diode, photodiode, organic FET and/or solar cell, comprises layer comprising ketopyrrole compound or corresponding oligomer or polymer.    USE - A semiconductor device including diode, photodiode, organic FET, solar cell, or device containing diode, photodiode, organic FET and/or solar cell.    ADVANTAGE - The ketopyrroles show good solubility in organic solvents and excellent film forming properties. High efficiency of energy conversion, excellent field-effect mobility, good on/off current ratios and/or excellent stability can be observed when ketopyrroles are used in semiconductor devices or organic photovoltaic devices (solar cells).    DETAILED DESCRIPTION - A semiconductor device including diode, photodiode, organic FET, solar cell, or device containing diode, photodiode, organic FET and/or solar cell, comprises layer comprising ketopyrrole compound of formula (I) or corresponding oligomer or polymer comprising repeating units of formula (Ia).    a, b, c, d, e, f=0-3;    A, A', R1, R2=H or E; 1-25C alkyl, 2-25C alkenyl or 2-24C alkynyl (all optionally substituted by E and/or in any C,C-single bond, if present, interrupted by D); cycloalkyl optionally substituted by E 1-3 times by 1-8C alkyl, 1-8C thioalkoxy or 1-8C alkoxy; cycloalkyl optionally condensed 1 or 2 times by Ph optionally substituted by E, preferably Ph substituted 1-3 times by 1-4C alkyl, halo, NO2 or CN cycloalkenyl group; or ketone, aldehyde, ester, carbamoyl, silyl, siloxanyl, Ar10 or -CR5R6-(CgH2g)Ar10;    g=0-4;or    R2+Ar1+vinyl moiety=aryl or heteroaryl optionally substituted by G;    X=CR;    R=R1 or ketopyrrole moiety of formula (Ib);    g=0 or 1;    Ar'=tetravalent residue connected to the rest of molecule by 2 chemical double bonds, preferably quinoid 5-10C ring systems including =C5H4= and =C(G)-Ar5-C(G')=;or    Ar1, Ar2, Ar2', Ar3, Ar3', Ar4, Ar4', Ar5=5-15C divalent carbocyclic moieties, 2-15C divalent heterocyclic moieties or 1-8 heteroatoms including O, N, S or Si (each containing conjugated or cross-conjugated double and/or triple bonds); or ethylenic or ethinic moieties (both optionally substituted by E);    R5, R6=H, F, CN, 1-4C alkyl optionally substituted by F, Cl or Br; or Ph optionally substituted 1-3 times with 1-4C alkyl;    Ar10=aryl or heteroaryl optionally substituted by G particularly Ph 1- or 2-naphthyl optionally substituted 1-3 times with 1-8C alkyl, 1-6C thioalkoxy and/or 1-8C alkoxy;    D=-CO-, -COO-, -S-, -SO-, -SO1-, -OP(O)(OR29)O-, -OP(O)(R'29)O-, -O-, -NR25-, -CR23=CR24- or -CC-;    E=-OR29, -SR29, -SOR29, -SO2R29, -NR25R26, -COR28, -COOR27, -CONR25R26 -CN, NO2, -OP(O)(OR29)2, -OP(O)(R'29)2, -Si(R'29)3 or halo;    G, G'=E, 1-18C alkyl optionally interrupted by D, or 1-18C alkoxy substituted by E and/or interrupted by D if containing greater than or equal to 2C;    R23, R24, R25, R26, R27, R28, R29=H, 1-18C alkoxy, 1-18C alkyl, 2-18C alkyl interrupted by -O-, or 6-18C aryl optionally substituted by 1-18C alkyl;and    R'29=R29 except H, or tautomer, oligomer or polymer.    INDEPENDENT CLAIMS are included for:    (1) preparation of organic semiconductor device comprising applying solution and/or dispersion of ketopyrrole compound of formula (I) and/or (Ia) in organic solvent to suitable substrate, and removing solvent; and    (2) use of ketopyrrole compound of formula (I) and/or (Ia) as charge-transport, semiconducting, electric conducting, photoconducting, light emitting material, surface-modifying material, electrode material in batteries, alignment layer, or in organic FETs, integrated circuits, thin film transistors, displays, radio frequency identification tags, electro- or photoluminescent devices, backlights of displays, photovoltaic or sensor devices, charge injection layers, Schottky diodes, memory devices including ferroelectric FET, planarizing layers, antistatics, conductive substrates or patterns, photoconductors or electrophotographic applications (recording).