TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The electron acceptor material and electron donor material are heat-treated, after treating with nonsolvent. Preferred Composition: The penetration depth of the nonsolvent with respect to optically active layer is 5-50%. The alkane-based nonsolvent is chosen from N-butane, N-pentane, N-hexane, N-octane, isooctane, N-dodecane, dichloromethane, cyclohexane and methylcyclohexane. The halohydrocarbon-based nonsolvent is chosen from methane, dichloromethane, methylene chloride, 1,1-dichloroethylene, ethylene dichloride, chloroform, 1,1-dichloroethane, trichloroethylene, carbon tetrachloride, chlorobenzene, O-dichlorobenzene and 1,1,2-trichlorobenzene fluorotrifluoranthene. The ether-based nonsolvent is chosen from tetrahydrofuran, 1,4-dioxane, diethylether and dibenzyl ether. The ketone-based nonsolvent is chosen from acetone, methyl ethyl ketone, cyclohexanone, diethylketone, acetophenone, methyl isobutyl ketone, methylisoamylketone, isophorone and di(isobutyl)ketone. The ester-based nonsolvent is chosen from ethylene carbonate, methyl acetate, ethyl formate, propylene-1,2- carbonate, ethyl acetate, diethyl carbonate, diethyl sulfate, N-butyl acetate, isobutyl acetate, 2- ethoxyethylacetate, isoamylacetate and isobutyl isobutyrate. The sulfur-based nonsolvent is chosen from carbon disulfide, dimethyl sulfoxide and ethanethiol. The alcohol-based nonsolvent is chosen from methanol, ethanol, allyl alcohol, 1-propanol, isopropanol, 1-butanol, 2-butanol, isobutanol, benzyl alcohol, cyclohexanol, diacetone alcohol, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, 2-methoxyethanol and 1-decanol, preferably methanol or 2-methoxyethanol. The acid-based nonsolvent is chosen from formic acid, acetic acid, benzene acid, oleic acid and stearic acid. The phenol-based nonsolvent is chosen from phenol, resorcinol, m-cresol and methyl salicylate. The polyol-based nonsolvent is chosen from ethylene glycol, glycerol, propylene glycol, diethylene glycol, triethyleneglycol and dipropylene glycol. The electron acceptor material is fullerene derivative, preferably 60-90C fullerene derivative with lowest unoccupied molecular orbit energy level of -2 eV to 6 eV. The electron donor material comprises electron donor having group of formulae (a)-(p) and electron acceptor having group of formulae (q)-(x). The electron acceptor material is preferably methyl-(6,6)-phenyl C61-butyrate. The organic layer comprises buffer layer having thickness of 1-60 nm.a=0-4;b=0-6;c=0-8;d,e=0-3;f,g=0-2;X1-X3=CRR', NR, O, SiRR', PR, S, GeRR', Se or Te;Y1-Y5=CR, N, SiR, P or GeR;R,R',R2-R5=H, D, halo, nitrile, nitro, imido, amide, hydroxy, or alkyl, cycloalkyl, alkoxy, aryloxy, alkyloxy, alkyl sulfoxy, aryl sulfoxy, alkenyl, silyl, boron, alkylamine, aralkylamine, arylamine, amine, heteroaryl, aryl, fluorenyl, carbazole or heterocyclyl (having heteroatom chosen from N, O or S) (all optionally substituted);andor R2+R3,R+R',R4+R5=condensed ring.    TECHNOLOGY FOCUS - POLYMERS - Preferred Composition: The electron donor material further contains a polymer having unit (A) of formula (a), (k) or (p), unit (B) of formula (i) and unit (C) of formula (ii). The electron donor material is preferably poly(3-hexylthiophene) or polymer having unit of formula (iii). The ratio of electron donor material and electron acceptor material is 1:10-10:1.x,y=more than 0 and less than 1;x+y=1;n=1-10000;X4,X5=X1;andR10-R12=H, or alkoxy or alkyl (both optionally substituted).Preferred Property: The thickness of the optically active layer is 50-300 nm.