TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Component: The photoactive material further comprises an electron acceptor material from a fullerene, e.g. 61C-phenyl-butyric acid methyl ester (PCBM).    TECHNOLOGY FOCUS - POLYMERS - Preferred Component: The photovoltaic cell includes a photoactive material comprising a polymer including two comonomer repeat units. The first comonomer repeat unit comprises a cyclopentadithiophene moiety (preferred), a silacyclopentadithiophene moiety, a cyclopentadithiazole moiety, a thiazolothiazole moiety, or a thiazole moiety. The cyclopentadithiophene moiety is substituted with substituent(s) from 1-20C alkyl, 1-20C alkoxy, 3-20C cycloalkyl, 1-20C heterocycloalkyl, (hetero)aryl, halo, CN, OR, C(O)R, C(O)OR, or SO2R. The cyclopentadithiophene moiety is substituted with hexyl, 2-ethylhexyl, or 3,7-dimethyloctyl. The first comonomer repeat unit comprises a cyclopentadithiophene moiety of formula (1).The second comonomer repeat unit comprises a benzothiadiazole moiety, a thiadiazoloquinoxaline moiety, a cyclopentadithiophene dioxide moiety, a cyclopentadithiophene monoxide moiety, a benzoisothiazole moiety, a benzothiazole moiety, a thiophene dioxide moiety, a cyclopentadithiophene dioxide moiety, a cyclopentadithiophene tetraoxide moiety, a thienothiophene moiety, a thienothiophene tetraoxide moiety, a dithienothiophene moiety, a dithienothiophene dioxide moiety, a dithienothiophene tetraoxide moiety, a tetrahydroisoindole moiety, a thienothiophene dioxide moiety, a dithienothiophene dioxide moiety, a fluorene moiety, a silole moiety, a cyclopentadithiophene moiety, a fluorenone moiety, a thiazole moiety, a selenophene moiety, a thiazolothiazole moiety, a cyclopentadithiazole moiety, a naphthothiadiazole moiety, a thienopyrazine moiety, a silacyclopentadithiophene moiety, an oxazole moiety, an imidazole moiety, a pyrimidine moiety, a benzoxazole moiety, or a benzimidazole moiety, of formulae (2-34) respectively. The second comonomer repeat unit is preferably 3,4-benzo-1,2,5-thiadiazole moiety.The polymer further comprises a third comonomer repeat unit comprising a thiophene moiety or a fluorene moiety which is substituted with substituent(s) from 1-20C alkyl, 1-20C alkoxy, (hetero)aryl, 3-20C cycloalkyl, or 3-20C heterocycloalkyl.R=H, 1-20C alkyl, 1-20C alkoxy, (hetero)aryl, 3-20C cycloalkyl, or 1-20C heterocycloalkyl; andR1-R4=H, 1-20C alkyl, 1-20C alkoxy, 3-20C cycloalkyl, 1-20C heterocycloalkyl, (hetero)aryl, halo, CN, OR, C(O)R, C(O)OR, or SO2R, preferably hexyl, 2-ethylhexyl, or 3,7-dimethyloctyl (for R1 and R2)X, Y= CH2, O, or S;R5-R6= H, 1-20C alkyl, 1-20C alkoxy, 3-20C cycloalkyl, 1-20C heterocycloalkyl, aryl, heteroaryl, halo, CN, OR, C(O)R, C(O)OR, or SO2R; andR7-R8=H, 1-20C alkyl, 1-20C alkoxy, aryl, heteroaryl, 3-20C cycloalkyl, or 3-20C heterocycloalkyl.