TECHNOLOGY FOCUS - ELECTRONICS - Preferred Cell: The photoelectric cell has a layer containing the composition or organic semiconductor polymer provided between electrodes, hole transportation layer provided between first electrode and the layer containing the polymer, electron carrying layer between second electrode and the layer containing the polymer. The first electrode is transparent electrode, and the second electrode is a metal electrode.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Compound: The n-type organic semiconductor compound is fullerene or its derivative(s), preferably phenyl-61C-butyric acid ester, diphenyl-62C-bis(butyric acid ester), phenyl-71C-butyric acid ester, phenyl-85C-butyric acid ester, or thienyl-61C-butyric acid ester.    TECHNOLOGY FOCUS - POLYMERS - Preparation: No general preparation given. Preferred Polymer: The structural unit (I) is of formula (I-1), (I-2) or (I-3). The polymer further contains structural unit of formula (II).Z1,Z2=S, O, Se or Te;Y'=C(R21) or N;andR',R21=H or substituent.The organic semiconductor polymer is copolymer. EXAMPLE - 7,7-Dihexyl-4,10-bis(tris(propan-2-yl)silyl)-3,11-dithia-5,9-diaza-7-silatricyclo(6.3.0.02,6)undeca-1(8),2(6),4,9-tetraene (1.35 g) was dissolved in dry tetrahydrofuran (27 mL), and reacted with N-bromo succinimide (0.73 g) at room temperature for 4 hours. The solvent was depressurizingly distilled, and purified to obtain 4,10-dibromo-7,7-dihexyl-3,11-dithia-5,9-diaza-7-silatricyclo(6.3.0.02,6)undeca-1(8),2(6),4,9-tetraene (0.94 g) with yield of 90%. The obtained compound dissolved in dimethylformamide was reacted with N,N-dimethylformamide (10 mL) containing bis(1,5-cyclooctadiene)nickel (0) (0.44 g), 1,5-cyclooctadiene (0.75 mL) and 2,2'-bipyridyl (0.27 g) in nitrogen atmosphere, at 60 degrees C for 24 hours. Mixture of hydrochloric acid and methanol was added to the reaction mixture and the obtained solid was washed with disodium ethylenediaminetetraacetate aqueous solution, sodium-diethyldithiocarbamate aqueous solution and methanol, and dried under reduced pressure to obtain polymer (0.47 g).