TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The photoactive region comprises donor material and acceptor material. The acceptor has lowest unoccupied molecular orbital energy (LUMO-1). The electron conducting exciton blocking layer has lowest unoccupied molecular orbital energy (LUMO-2). The lowest unoccupied molecular orbital energy and lowest unoccupied molecular orbital energy are aligned to permit electron transport directly from the acceptor material to the cathode. The blocking region further comprises wide-gap electron conducting exciton blocking material. The electrode comprises transparent conducting oxides, thin metal layers, transparent conducting polymers or non-metallic material, or metallic material chosen from silver, gold, titanium, tin, and aluminum. The conducting oxides are chosen from indium tin oxide, tin oxide, gallium indium tin oxide, zinc oxide, and zinc indium tin oxide. The thin metal layers are silver, aluminum or silver. Preferred Properties: The energy gap between primary lowest unoccupied molecular orbital energy and secondary lowest unoccupied molecular orbital energy is 0.3 eV or less. The blocking region has thickness of 10-100 nm. The electron conducting material has thickness of 2-10 nm. The wide-gap electron conducting exciton blocking material has thickness of 5-100 nm.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The donor material comprises squarine, boron subphthalocyanine chloride, copper phthalocyanine, chloroaluminum phthalocyanine, poly(3-hexylthiophene), tin phthalocyanine, pentacene, tetracene or diindenoperylene. The acceptor material is fullerene (C60), fullerene (C70), 3,4,9,10-perylenetetracarboxylic dianhydride, perfluorinated copper phthalocyanine, butyric acid methyl ester or acceptor (PC70BM). The electron conducting material comprises 3,4,9,10-perylenetetracarboxylic bisbenzimidazole. The wide-gap electron conducting exciton blocking material comprises 1,4,5,8-napthalene-tetracarboxylic-dianhydride. Preferred Properties: The thickness of 1,4,5,8-napthalene-tetracarboxylic-dianhydride is 5-100 nm. The thickness of 3,4,9,10-perylenetetracarboxylic bisbenzimidazole is 5 nm or less.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The transparent conductive polymers comprise polyanaline, 3,4-polyethylenedioxythiophene and polystyrenesulfonate.