TECHNOLOGY FOCUS - ELECTRONICS - Preferred Components: The hole extracting layer comprises a metal oxide or an organic electron accepting transport material. The active layer comprises a bulk heterojunction (BHJ) active layer that comprises an electron-donating material and an electron-accepting material. The polymer solar cell further comprises a cathode interlayer situated between the active layer and the transparent cathode.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The metal oxide comprises molybdenum trioxide, vanadium pentoxide, nickel oxide or tungsten trioxide. The metal oxide comprises many nanoparticles. The transparent cathode comprises indium-tin-oxide (ITO), ITO/silver/ITO, aluminum doped zinc oxide/metal, a thin metal layer, doped or undoped single walled carbon nanotubes or patterned metal nanowires that comprise gold, silver, or copper. The thin metal layer comprises silver, gold, palladium, platinum, titanium, vanadium, zinc, tin, aluminum, cobalt, nickel, copper or chromium. The anode comprises a metal or a metal alloy, where the metal comprises silver, calcium, aluminum, magnesium, titanium, tungsten or gold. The cathode interlayer comprises zinc oxide, lithium fluoride, lithium cobalt oxide, cesium fluoride, cesium carbonate, titanium dioxide or a polar or ionic polymer. The polar or ionic polymer comprises polyethylene oxide.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The organic electron accepting transport material comprises 1,4,5,8,9,12-hexaazatriphenylene-2,3,6,7,10,11-hexanitrile, copper hexadecafluorophthalocyanine, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane, 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA), fluoro-substituted PTCDA, cyano-substituted PTCDA, naphthalene-tetracarboxylic-dianhydride (NTCDA), fluoro-substituted NTCDA, cyano-substituted NTCDA or 3,4,9,10-perylene tetracarboxylic bisbenzimidazole. The hole transport/electron blocking layer comprises 4,4,4'' tris(N-(3-methylphenyl)-N-phenyl amino)tri phenyl amine, poly(9,9-dioctylfluorene-co-N-(4-(3-methylpropyl))diphenylamine) (TFB), poly(N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine), 4,4'-bis(N-(p-tolyl)-N-phenyl-amino)biphenyl, 4,4'-bis(N-(1-naphthyl)-N-phenyl-amino)biphenyl, 4,4'-(bis-((4-di-n-hexylamino)benzylideneamino))stilbene, 4,4'-(bis-((4-diphenylamino) benzylideneamino))stilbene or TFB analogue. The electron-donating material comprises poly((4,4'-bis(2-ethylhexyl)dithienol (3,2-b:2',3'-d)silole)-2,6-diyl-alt-(2,1,3-benzothiadiazole)-4, 7-diyl) (DTSBTD), poly(3-hexylthiophene), poly(2,7-(9-(2'-ethylhexyl)-9-hexyl-fluorene)-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)) (PFDTBT), poly(2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta(2,1-b;3,4-6')dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)) (PCPDTBT), poly(p-phenylene ethynylene)-alt-poly(p-phenylene-vinylene), poly((2,7-(9-(2,-ethylhexyl)-9-hexyl-fluorene)-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole))-co-(2,7-(9-(2'-ethylhexyl)-9-hexyl-fluorene)-alt-2,5-thiophene)) (APFO-5), poly(4,8-bis-alkyloxybenzo(1,2-b:4,5-b')dithiophene-2,6-diyl-alt-(alkylthieno(3,4-b)thiophene-2-(2-ethyl-1-hexanone)-2,6-diyl) (PBDTTT-C), poly(4,8-bis-alkyloxybenzo(1,2-b:4,5-b')dithiophene-2,6-diyl-alt-(thieno(3,4-b)thiophene-2-carboxylate)-2,6-diyl) (PBDTTT-E), poly(N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1,3'-benzothiadiazole)) (PCDTBT), aluminum phthalocyanine chloride or copper phthalocyanine. The electron-accepting material comprises (6,6)-phenyl-C71 butyric acid methyl ester (PC70 BM), (6,6)-phenyl-C61 butyric acid methyl ester (PC60BM), zinc oxide nanoparticles, N-alkyl or N-aryl perylenediimides, perylenediimide containing polymers, poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-(1-cyanovinylene)phenylene) (CNPPV), titanium dioxide nanoparticles or cadmium/lead-based nanoparticles.