TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Compound: The buffer layer contains bathocupuroine. The electron-accepting compound is fullerene and/or fullerene compound. Preferred Composition: The organic photoelectric transducer contains fullerene derivative (10 weight parts or more) dissolved with respect to dichlorobenzene (90 weight parts), and/or xylene (90 weight parts).    TECHNOLOGY FOCUS - POLYMERS - Preferred Compounds: The polymer further contains thiophene-containing compound of formula (4 and 5). The thiophene-containing repeating unit (2), and another thiophene-containing repeating unit (3) are connected to form a sulfur-containing repeating unit of formula (6). Alternately, the alkoxy group-containing repeating unit (1b), and thiophene-containing repeating unit (3) are connected to form sulfur-containing repeating unit of formula (1c). The alkyl group-containing repeating unit (1) is of formula (7). The thiophene-containing repeating unit (3) is of formula (8).R3,R4=same as defined above;m,n=1-3;m+n=3-6;E,F=optionally substituted naphthalene ring, or optionally substituted benzene ring;R11-R14=same as R1-R4;R23,R24=same as defined above;anda,b=3-6.The difference between the maximum number of carbons in the carbon principle chain contained in the alkyl group (R11 or R12) and the maximum number of carbons in the carbon principle chain contained in the alkyl group (R13 or R14) is 2 or more. Preferred Composition: The content of alkyl group-containing repeating unit (7) is 50 mol% or more with respect to whole of thiophene-containing repeating unit (8). Preferred Property: The polymer has number average molecular weight of 103-108, based on polystyrene conversion. Preferred Layer: An organic photoelectric transducer formed using polymer has a secondary organic layer containing electron donar, and a primary organic layer provided between a pair of transparent or semi-transparent electrode, and electrode. The primary organic layer contains electron-accepting compound. The electron donar is a polymer. The organic photoelectric transducer further has a buffer layer provided between the primary organic layer and the electrodes. An organic thin film formed using the polymer contains antioxidant and/or ultraviolet absorber. Preferred Definitions:    R1-R4,R21-R24=5-20C linear or branched alkyl;and    C,D=optionally substituted naphthalene ring.    EXAMPLE - 9,9-dihexyl fluorene-2,7-diboronic-acid ester (8.012 g), and 5,5""-3,4"-dihexyl-(alpha )penta thiophene (13.16) of formula (Ia) were reacted, to obtain penta thienyl-fluorene copolymer (polymer A) (12.21) having number average molecular weight of 4.5x 104 based on polystyrene conversion. An organic photoelectric transducer formed using the obtained penta thienyl-fluorene copolymer had excellent charge transportability, and photoelectric conversion efficiency.    t=degree of polymerization.