TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The device such as an organic photovoltaic device comprising an anode (22), a cathode (26), optionally at least one anode interlayer, optionally at least one cathode interlayer, and the photoactive layer in between the anode and the cathode.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The electron-acceptor polymer is of formulae (I)-(VIII) or a random copolymer of formula (r1) or (r2). The electron-donor polymer: has an alternating push-pull structure of formula (-D1a-Q1a-); is an alternating copolymer which is is 22 thiophene copolymer e.g. substituted thiophene copolymer of formulae (v1)-(v5); and a random copolymer which is 17 thiophene copolymer e.g. substituted thiophene copolymer formulae (u1)-(u5).A1a, A2a = optionally substituted fused ring, preferably perylen-1,3,4,7,9,10-hexayl, perylen-1,3,4,5,9,10-hexayl, naphthalen-1,2,4,5,6,8-hexayl, anthracen-2,3,6,7,9,10-hexayl, coronen-1,3,6,7,10,12-hexayl or 3,15-dithianonacyclo(20.6.2.0(2,6).0(7,27).0(10,26).0(13,25).0(14,18).0(19,24).0(23,28))triaconta-1(28),2(6),4,7(27),8,10,12,14(18),16,19,21,23,25,29-tetradecaen-4,9,11,16,21,30-hexayl;R1a, R2a = 1-30C alkyl, 2-30C alkenyl, 1-30C haloalkyl, 6-20C aryl or 5-14 membered heteroaryl, where the 6-20C aryl and 5-14 membered heteroaryl optionally are substituted with alkyl, 2-30C alkenyl or 1-30C haloalkyl, preferably sec-butyl, 1-methyl-butyl, 1-methyl-pentyl, 1-methyl-heptyl, 1-ethyl-pentyl, 2-ethyl-hexyl, 3,7-dimethyl-octyl, 3,7-dimethyl-oct-6-enyl, 2-octyl-dodecyl, 2-hexyl-decyl, 2-butyl-hexyl or 1-hexyl-heptyl;M1a, M2a = repeating unit comprising at least one conjugated moiety that does not include arylene diimide, where at least one is true i.e. A2a is different from A1a, R2a is different from R1a, or M2a is different from M1a;p, q = 0.1-0.9;p+q = 1;n = 2-5000, preferably 5-5000;R1b, R2b = H, F, Cl, -CN or -L1a-R1c;L1a = -O-, -S-, -C(O), -C(O)O- or covalent bond;R1c = 6-20C alkyl, 6-20C alkenyl or 6-20C haloalkyl;m = 1-6;D1a = donor subunit comprising a bridged dithiophene moiety, where the bridged dithiophene moiety is of formulae (a1)-(a10) or (s1)-(s6) or dithieno(3,2-b;2',3'-d)thiophen-2,6-diyl;Q1a = acceptor subunit comprising an electron-poor conjugated moiety of formulae (w1)-(w15), where either D1a or Q1a comprises at least one thienyl;R3a = optionally branched 6-40C alkyl;Q2a = S-substituted bicyclyl moiety of formula (b1), where the S-substituted bicyclyl moiety is benzo(b)thiophen-2-yl, naphtho(2,3-b)thiophen-2-yl, benzo(1,2-b;5,4-b')dithiophen-2-yl, 7H-5( lambda 4)-benzo(1,2-b;4,5-b')dithiophen-2-yl, thieno(2,3-b)thiophen-2-yl, 3b,6a-dihydro-dithieno(2,3-b;3',2'-d)thiophen-2-yl, 6,6a-dihydro-3bH-5( lambda (4))-dithieno(2,3-b;3',4'-d)thiophen-2-yl, benzo(b)thieno(3,2-d)thiophen-2-yl, 6H-4( lambda (4))-thieno(3,2-b)thiophen-2-yl, 7aH-4( lambda (4))-dithieno(3,2-b;2',3'-d)thiophen-2-yl, 7,7a-dihydro-6( lambda (4),4( lambda (4))-dithieno(3,2-b;3',4'-d)thiophen-2-yl or benzo(b)thieno(2,3-d)thiophen-2-yl (all optionally substituted by 1-2 R4b);R4b = 3-40 alkyl;R1d = 3-40C alkyl, 3-40C alkenyl or 3-40C haloalkyl;R1f = H, F, Cl, -CN, -S(O)2-1-20C alkyl, -C(O)-O-1-20C alkyl, -C(O)-1-20C alkyl, 1-20C alkyl, 2-20C alkenyl, 1-20C alkoxy, 1-20C alkylthio or 1-20C haloalkyl;R1n = L1a-R1j, -L1a-Ar1j or -L1a-Ar1j-Ar1j;L1a = -O-, -S- or covalent bond;R1j = 3-40C alkyl, 3-40C alkenyl or 3-40C haloalkyl;Ar1j = 5-14 membered heteroaryl (optionally substituted with 1-2 R1j);R1m = H or R2j;R2j = 6-20C alkyl, 6-20C alkenyl or 6-20C haloalkyl;Z1a = electron-poor conjugated moiety of formulae (w1)-(w15);x, y = 0.1-0.9, preferably 0.2-0.8;x+y = 1;R1p = optionally branched 3-40C alkyl;R2p = H or 6-20C alkyl;r = 0 or 1;R1w = 6-20 alkyl;R2f = H, F, Cl, C(O)R1e, C(O)OR1e or S(O)2R1e; andR1e = optionally branched 6-20C alkyl.