TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Device: The device comprises cathode; optionally a transition layer; the photovoltaic layer; optionally a smoothing layer; anode; substrate; and optionally further comprises middle electrode; optionally a further electrode; optionally a transition layer; further photovoltaic layer; optionally a smoothing layer.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The stabilizing agent is selected from a UV absorbing agent and anti-radical agent (preferably hydroxybenzophenones, hydroxyphenyl benzotriazoles, oxalic acid anilides, hydroxyphenyl triazines, merocyanines and/or hindered phenols). The UV absorbing agent is selected from 7 compounds as given in the specification e.g. 2-hydroxybenzophenone of formula (I), 2-hydroxyphenylbenzotriazole of formula (IIa), (IIb) or (IIc) (including their E,E-, E,Z- and Z,Z-geometrical isomers) (preferably 67 compounds are given in the specification e.g. 4-hydroxy, 4-methoxy, 4-octyloxy, 4-decyloxy, 4-dodecyloxy, 4-benzyloxy, and 2'-hydroxy-4,4'-dimethoxy derivative of the 2-hydroxybenzophenone; 2-(2'-hydroxy-5'-methylphenyl)-benzotriazole, 2-(3',5'-di-tert-butyl-2'-hydroxyphenyl)benzotriazole, 2-(5'-tert-butyl-2'-hydroxyphenyl)benzotriazole, 2-(2'-hydroxy-5'-(1,1,3,3-tetramethylbutyl)phenyl)benzotriazole, 2-(3',5'-di-tert-butyl-2'-hydroxyphenyl)-5-chloro-benzotriazole, 2-(3'-tert-butyl-2'-hydroxy-5'-methylphenyl)-5-chloro-benzotriazole, 2-(3'-sec-butyl-5'-tert-butyl-2'-hydroxyphenyl)benzotriazole, 2-(2'-hydroxy-4'-octyloxyphenyl)benzotriazole, 2-(3',5'-di-tert-amyl-2'-hydroxyphenyl)benzotriazole, 2-(3',5'-bis-( alpha , alpha -dimethylbenzyl)-2'-hydroxyphenyl)benzotriazole, 2-(3'-tert-butyl-2'-hydroxy-5'-(2- octyloxycarbonylethyl)phenyl)-5-chloro-benzotriazole or 2-(3'-tert-butyl-5'-(2-(2- ethylhexyloxy)-carbonylethyl)-2'-hydroxyphenyl)-5-chloro-benzotriazole). The anti-radical agent is a compound of (III). The mixture additionally comprises at least one electron acceptor material. The electron acceptor material is an optionally suitably modified fullerene (preferably having 60-96 carbon atoms), where in the mixture, the weight ratio of the electron acceptor material relative to the diketopyrrolopyrrole polymer is 0.1:1-10:1 (preferably 0.5:1-3:1, especially 0.8:1-2:1).v=1-3;w=1 or 2;Z1=H, halo, OH or 1-12C alkoxy;R1=H, 1-24C alkyl, 1-4C phenylalkyl, 5-8C cycloalkyl or group of formula -C(R4)(R5)-CnH2n+1-m-(M1)m (i);R4,R5=1-5C alkyl;orR4+CnH2n+1-m-(M1)m=5-12C cycloalkyl;m,n1=1 or 2;n=2-20;M1=group of formula -COOR6;R6=H, 1-12C alkyl, 1-20C 1-4C alkoxy-1-20C-alkyl or phenyl-1-4C alkyl;R2=H, halo, 1-18C alkyl, 2-4C alkyl (substituted by 2-6C alkanoyloxy or 3-6C alkenoyloxy), or phenyl-1-4C alkyl;R3=H, Cl, 1-4C alkyl or 1-4C alkoxy or -COOR6;T=H or 1-6C alkyl;T1=H, Cl or 1-4C alkyl or 1-4C alkoxy;T2=Cl, group of formula -N(T4)(T5) (ii) or -N(T6)-T10-N(T6)- (iii);T3=H, 1-18C alkyl (optionally mono- to tri-substituted by OH or -OCOT6), 3-18C alkyl (interrupted at least one time by -O- or -NT6- and optionally substituted by OH or -OCOT6), 5-12C cycloalkyl (optionally substituted by OH and/or 1-4C alkyl), 2-18C alkenyl (optionally substituted by OH), phenyl-1-4C alkyl, or radical of the formula -CH2CH(OH)-T7 or group of formula (v);T4,T5=H, 1-8C alkyl, 3-18C alkyl (interrupted at least one times by -O- or -NT6-), 5-12C cycloalkyl, phenyl (optionally substituted by 1-4C alkyl), 3-8C alkenyl, phenyl-1-4C alkyl or hydroxy-2-4C alkyl;T6=H, 1-18C alkyl, 5-12C cycloalkyl, 3-8C alkenyl, phenyl (optionally substituted by 1-4C alkyl) or phenyl-1-4C alkyl;T7=H, 1-18C alkyl, phenyl (optionally substituted by OH), phenyl-1-4C alkyl, or -CH2OT8;T8=1-18C alkyl, 3-8C alkenyl, 5-10 cycloalkyl, phenyl (optionally substituted by 1-4C alkyl) or phenyl-1-4C alkyl;T9=2-8C alkylene, 4-8C alkenylene, 4C alkynylene, cyclohexylene, 2-8C alkylene (interrupted at least one time by -O-, or group of formula -CH2CH(OH)CH2OT11OCH2CH(OH)CH2- or -CH2-C(CH2OH)2-CH2-;T10=2-20C alkylene (interrupted by at least one time by -O-) or cyclohexylene;T11=2-8C alkylene, 2-18C alkylene (interrupted at least one times by -O-), 1,3-cyclohexylene, 1,4-cyclohexylene, 1,3-phenylene or 1,4-phenylene;orNT10+NT6=piperazine ring;R'2=1-12C alkyl;k=1-4;G1=H, 1-22C alkyl, 1-22C alkylthio, 2-22C alkylthioalkyl, 5-7C cycloalkyl, phenyl, 7-9C phenylalkyl or SO3M2;G2=1-22C alkyl, 5-7C cycloalkyl, phenyl, or 7-9C phenylalkyl;Q1=-Cm1H2m1-, -CH-(Cm1H2m1+1), -Cm1H2m1-NH, group of formula (vi) or (vii);T'=-Cn2H2n2-, -(CH2)n2-O-CH2-, phenylene, -Cn2H2n2-NH-C(O)- or group of formula (viii);V1=-O- or -NH-;a=0-2;b,c,d,g=0 or 1;e=1-4;f=1-3;m1,n2,p=1-3;q=0-3;G3=K1-K5;K1=H, 1-22C alkyl, 5-7C cycloalkyl, 1-22C alkylthio, 2-22C alkylthioalkyl, 2-18C alkenyl, 1-18C phenylalkyl, M2, SO3M2, group of formula (ix)-(xi);K2=propyl (substituted by OH and/or 2-22C alkanoyloxy);M2=alkali, ammonium or H;K3=direct bond, -CH2-, -group of formula (xviii) or -S-;K4=group of formula (xii), (xiii), (xv), (xiv) or (xvi);K5=group of formula (xvii);G4=H or 1-22C alkyl.Provided that at least one of R1 and R2 is other than H; when n1 is 1, then T2 is Cl or group (ii), when n1 is 2, then T2 is group (iii); when e is 1, then G3 is K1 or K2; when e is 2, then b and c is 0 or 1 and G3 is K3 or K2; when e is 3, then b and c is 0 or 1 and G3 is K4; when e is 4, then b and c is 0 or 1 and G3 is K5.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The diketopyrrolopyrrole polymer has at least one diketopyrrolopyrrole (DPP) skeletons of the formula (V) in the repeating unit. The diketopyrrolopyrrole polymer comprises at least one repeating unit of formula (V). The diketopyrrolopyrrole polymer is selected from 63 compounds as given in the specification e.g. compound of formulae (ia)-(id). The average molecular weight of the diketopyrrolopyrrole polymer as determined by high temperature gel permeation chromatography using polystyrene standards, is 4000-2000000 Daltons (preferably 10000-1000000, especially 10000-100000) Daltons. The mixture comprising the diketopyrrolopyrrole polymer and the stabilizing agent with a weight ratio of stabilizing agent relative to the diketopyrrolopyrrole polymer of 0.0001:1-0.1:1 (preferably 0.001:1-0.05:1, especially 0.005:1-0.025:1).R1a,R2a=H, 1-10C alkyl, -COOR106 or 1-100C alkyl (optionally substituted by halo, OH, nitro, -CN or 6-18C aryl, and/or interrupted by -O-, -COO-, -OCO-, or -S-), 7-100C arylalkyl, carbamoyl, 5-12C cycloalkyl (optionally mono- to tri-substituted by 1-8C alkyl or 1-8C alkoxy), 6-24C aryl (preferably phenyl or 1- or 2-naphthyl (optionally mono- to tri-substituted by 1-8C alkyl, 1-25C thioalkoxy or 1-25C alkoxy)) or pentafluorophenyl;R106=1-50C alkyl (preferably 4-25C alkyl);R'1a,R'2a=H, 1-100C alkyl, such as 6-24C alkyl (optionally substituted by halo, OH, nitro, -CN or 6-18C aryl or is interrupted by -O-, -COO-, -OCO-, or -S-), COO-1-50C alkyl, 7-10C arylalkyl, carbamoyl, 5-12C cycloalkyl (optionally mono- to tri-substituted by 1-8C alkyl or 1-8C alkoxy), 6-24C aryl (preferably phenyl or 1- or 2-naphthyl (optionally mono- to tri-substituted by 1-8C alkyl, 1-8C thioalkoxy or 1-8C alkoxy)), or pentafluorophenyl (preferably 8-36C alkyl groups (optionally branched));Ar=12 groups are given in the specification e.g. 1,4-phenylen-diyl, 1,3-phenylen-diyl, biphenyl-4,4'-diyl, biphenyl-3-yl (optionally substituted), thiophen-2,5-diyl (substituted by R'6) or phenylen-1,4-diyl (substituted at position 3 by R32);R'6=H, 1-18C alkyl or 1-18C alkoxy;R32=methyl, Cl, or methoxy;R1b,R2b=1-36C alkyl, preferably 8-36C alkyl);n3=4-1000 (preferably 4-200, especially 5-100);R1c=8-38C alkyl;R3b,R15,R'15=1-18C alkyl (preferably 4-18C alkyl);y=0.995-0.005 (preferably 0.99-0.01). EXAMPLE - No suitable example given.