TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Cell: The organic solar cell further comprises at least one of an electron transporting layer (ETL) and a hole transporting layer (HTL) between the photoactive layer and one of the first electrode and the second electrode. Preferred Method: The forming a photoactive layer involves mixing a photoactive material, an ultraviolet (UV) absorber, and a solvent to provide a mixture, and coating the mixture on the one surface of the first electrode.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The ultraviolet (UV) absorber absorbs light having a wavelength of 100-400 (preferably 200-330, especially 250-325) nm. The ultraviolet (UV) absorber emits light having a wavelength of 150-500 (preferably 320-450). The photoactive layer contains the ultraviolet (UV) absorber (0.01-30, preferably 0.1-10 parts by weight). The photoactive layer includes bi-layer structure, a multi-junction structure and a bulk heterojunction (BHJ) structure. The photoactive material comprises a p-type semiconductor material, and an n-type semiconductor material. The photoactive material comprises at least two of phthalocyanine, tin (II) phthalocyanine (SnPc), copper phthalocyanine, triarylamine, bezidine, pyrazoline, styrylamine, hydrazone, carbazole, thiophene, 3,4-ethylenedioxythiophene (EDOT), pyrrole, phenanthrene, tetracene, naphthalene, rubrene, 1,4,5,8-naphthalene-tetracarboxylic dianhydride (NTCDA), 8-hydroxyquinoline aluminum salt, fullerene (C60, C70, C74, C76, C78, C82, C84, C720, and/or C860), 1-(3-methoxy-carbonyl)propyl-1-phenyl(6,6)C61 (PCBM), C71-PCBM, C84-PCBM, bis-PCBM, perylene, CdS, CdTe, CdSe, ZnO, and/or its derivative. The solvent for providing the photoactive layer comprises deionized water, methanol, ethanol, propanol, 1-butanol, isopropanol, 2-methoxyethanol, 2-ethoxyethanol, 2-propoxyethanol 2-butoxyethanol, methylcellosolve, ethylcellosolve, diethylene glycol methylether, diethylene glycol ethylether, dipropylene glycol methylether, toluene, xylene, hexane, heptane, octane, ethylacetate, butylacetate, diethylene glycol dimethylether, diethylene glycol dimethylethylether, methylmethoxy propionate, ethylethoxy propionate, ethyl lactate, propylene glycol methyletheracetate, propylene glycol methylether, propylene glycol propylether, methylcellosolve acetate, ethylcellosolve acetate, diethylene glycol methylacetate, diethylene glycol ethylacetate, acetone, chloroform, methylisobutylketone, cyclohexanone, dimethyl formamide(DMF), N,N-dimethyl acetamide(DMAc), N-methyl-2-pyrrolidone, gamma-butyrolactone, diethylether, ethylene glycol dimethylether, diglyme, tetrahydrofuran, chlorobenzene, dichlorobenzene, acetylacetone, acetonitrile, bromobenzene, 1-chloronaphthalene, fluorobenzene, 1,2,4-trichlorobenzene, 2-bromothiophene, benzaldehyde, acetophenone, ethylene dichloride, 1,1,2,2-tetrachloroethane, odobenzene, 1-bromonaphthalene, nitrobenzene, pyridine, di-(2-chloroethyl)ether, benzyl acetate, cyclohexyl chloride, tetrahydronaphthalene, 1-iodonaphthalene, cyclohexanone, 1,1,2-trichloroethane, trichloroethylene, 2-chlorothiophene, 1,1,1-trichloroethane, styrene, diethyl sulfide, methylene diiodide, 1,1,2,2-tetrabromoethane, 1-chlorobutane, ethyl benzene, butanethiol, benzene, thiophene, methylene dichloride, 1,4-dioxane, cyclohexylamine, furan, carbon tetrachloride, tetrahydrofuran, N-methylpyrrolidine, methyl ethyl ketone, methyl isobutyl ketone, cyclohexane, and/or 2-nitropropane. The photoactive material and ultraviolet (UV) absorber have a radius of interaction (Ra) of less than or equal to 7 (preferably less than or equal to 5). The ultraviolet (UV) absorber comprises olefin compound of formula (I).R1-R4=1-30C alkyl, 3-30C cycloalkyl group, 2-30C heterocycloalkyl (all optionally substituted), or H;n1 and n2=0-5.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The photoactive material comprises at least two of polyaniline, polypyrrole, polythiophene, poly(p-phenylenevinylene), poly(2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene) (MEH-PPV), poly(2-methoxy-5-(3,7-dimethyloctyloxy)-1,4-phenylene-vinylene) (MDMO-PPV), pentacene, poly(3,4-ethylenedioxythiophene) (PEDOT), poly(3-alkylthiophene), poly((4,8-bis(octyloxy)benzo(1,2-b:4,5-b')dithiophene-2,6-diyl)(2-((dodecyloxy)carbon yl)thieno(3,4-b)thiophenediyl)) (PTB1), poly((4,8-bis(2-ethylhexyloxy)benzo(1,2-b:4,5-b')dithiophene-2,6-diyl)(2-((2-ethylhexyloxy)carbonyl)-3-fluorothieno(3,4-b)thiophenediyl)) (PTB7) and/or its derivative. SPECIFIC COMPOUNDS - 1 Compound is specified as compound (I) i.e. (E)-1,2-diphenylethene.