TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: In the solar cell, one of the cathode and the anode includes one of indium tin oxide, indium-doped zinc oxide, tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, and the other of the cathode and the anode includes one of aluminum, silver, gold, and lithium.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The electron acceptor includes: one of a fullerene and a fullerene derivative; and one of C60, C70, C74, C76, C78, C82, C84, C720, C860, 1-(3-methoxy-carbonyl)propyl-1-phenyl(6,6) C61 (PCBM), C71-PCBM, C84-PCBM and/or bis-PCBM.    TECHNOLOGY FOCUS - POLYMERS - Preparation: No preparation method is given. Preferred Components: The polymer further comprises: a benzo(1,2-b;4,5-b')dithiophene moiety of formula (II); a thieno(3,4-b)thiophene moiety of formula (V); and a benzo(1,2-b;4,5-b')dithiophene moiety of formula (VI). (I) and (II): are included at a mole ratio of 1:0.5 to 1:2.5; and form a repeating unit, where the repeating unit includes one of a repeating unit having a benzo(1,2-b;4,5-b')dithiophene structure of formulae (III) and/or (IV). (V) and (VI) form a repeating unit, where the repeating unit includes a benzo(1,2-b;4,5-b')dithiophene repeating unit of formula (VII). The polymer includes one of a copolymer having a benzo(1,2-b;4,5-b')dithiophene structure of formulae (VIII) and/or (IX). The polymer has: a bandgap of 1.2-2.5 electron volt (eV); and a number average molecular weight of 1000-800000 (preferably 2000-100000). In formula (II):X3, X4 = 1-20C aliphatic, 1-20C alkoxy, 1-20C ketone, 1-20C ester (all optionally substituted), H, halo, hydroxyl, thiol and/or -SR101;R101 = 1-20C aliphatic, 2-30C aromatic or 2-30C heterocycloalkyl (all optionally substituted);R1, R2 = 1-20C alkyl, 3-20C cycloalkyl, 1-20C alkoxy, 6-30C aryl, 2-30C heteroaryl (all optionally substituted), H, organic group including at least one of -O-, -S-, -SO2-, -CO-, -OCO-, -COO-, -CH=CH-, and -CC-, and/or -SiR102R103; andR102, R103 = 1-20C alkyl, 3-20C cycloalkyl, 1-20C alkoxy, 6-30C aryl, 2-30C heteroaryl (all optionally substituted), and/or H.In formula (V):X12, X13 = 1-20C alkyl, 3-20C cycloalkyl, 6-30C aryl, 2-30C heteroaryl, 1-20C alkoxy, 1-30C ketone, 1-20C ester (all optionally substituted), H and/or halo.In formula (VI):X10, X11 = 1-20C aliphatic, 1-20C alkoxy, 1-20C ketone, 1-20C ester (all optionally substituted), H, halo, hydroxyl, thiol and/or -SR104;R104 = 1-20C aliphatic, 2-30C aromatic or 2-30C heterocycloalkyl (all optionally substituted);R5, R6 = 1-20C alkyl, 3-20C cycloalkyl, 1-20C alkoxy, 6-30C aryl, 2-30C heteroaryl (all optionally substituted), H, organic group including at least one of -O-, -S-, -SO2-, -CO-, -OCO-, -COO-, -CH=CH-, and -CC-, and/or -SiR105R106; andR105, R106 = 1-20C alkyl, 3-20C cycloalkyl, 1-20C alkoxy, 6-30C aryl, 2-30C heteroaryl (all optionally substituted) and/or H.In formula (III) and (IV):X2 = H, halo and/or optionally substituted 1-20C alkyl;X3, X4 = 1-20C alkyl, 1-20C alkoxy (both optionally substituted) or -SR101;R101 = optionally substituted 1-20C alkyl;X7-X9 = optionally substituted divalent 1-10C aliphatic;R1, R2 = H or optionally substituted 1-10C alkyl; andR3, R4 = H or optionally substituted 1-10C aliphatic.In formula (VII):X10, X11 = H or optionally substituted 1-20C alkoxy;X12, X13 = 1-20C ketone, 1-20C aryl (both optionally substituted), H or halo; andR5, R6 = H or optionally substituted 1-20C alkyl.In formula (VIII) and (IX):X2 = H, halo and/or optionally substituted 1-20C alkyl;X3, X4 = 1-20C alkyl, 1-20C alkoxy (both optionally substituted) or -SR101;R101 = optionally substituted 1-20C alkyl;X7-X9 = optionally substituted divalent 1-10C aliphatic;X10, X11 = H or optionally substituted 1-20C alkoxy;X12, X13 = 1-30C ketone, 1-30C aryl (both optionally substituted), H or halo;R1-R6 = H or optionally substituted 1-10C alkyl; andx, y = 0-10. EXAMPLE - No suitable example given.