TECHNOLOGY FOCUS - POLYMERS - Preparation (disclosed): The high-molecular compound is obtained by carrying out polymerization by Stille coupling of a dithienyl-dihydropyrrolo-pyrrole-dione derivative of formula (III) and bisthieno-pyran derivative of formula (IV).Z=bromo, iodo or chloro;andZ2=organic tin residue.Preferred Composition: The quantity of electron-accepting compound contained in the functional layer is 10-1000 parts weight with respect to 100 parts weight of high-molecular compound. The electron-accepting compound is a fullerene derivative. Preferred Definitions:    Q,R=H, 1-20C alkyl, or phenyl.    EXAMPLE - (In mg) 3,6-bis-(5-bromo-thiophen-2-yl)-2,5-dihexyl-2,5-dihydro-pyrrolo(3,4-c)pyrrole-1,4-dione (115), 7-(dibutyl-pentyl-stannanyl)-5,5-bis-(3,7-dimethyl-octyl)-2-tributylstannanyl-5H-4-oxa-1,8-dithia-as-indacene (200), and toluene (16 ml) were mixed to obtain a toluene solution, which was bubbled with argon for 30 minutes. Tris(2-tolyl)phosphine (5.2) and tris(dibenzylidene acetone)dipalladium (2.61) were added and stirred at 100 degrees C for 5 hours. Phenyl bromide (100) was added to the reaction liquid and stirred for 5 hours. The reaction mixture was cooled to 25 degrees C and poured into methanol (300 mL). The precipitated polymer was filtered and extracted using methanol, acetone and hexane for 5 hours. The polymer was dissolved in toluene (100 mL), and sodium diethyldithiocarbamate (3 g) and water (100 mL) were added and stirred for 8 hours. The organic layer was washed with water (50 ml), 3 wt.% acetic acid aqueous solution (50 mL), water (50 mL), 5 wt.% potassium fluoride aqueous solution (50 mL), and water (50 mL). The obtained solution was poured into methanol and polymer was deposited. The polymer was filtered, dried, and dissolved in o-dichlorobenzene (50 mL). The obtained solution was poured into methanol, and polymer was deposited, filtered and dried to obtain purified polymer (83). The polymer provides thin-film transistor having excellent field effect mobility.