TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Component: The metal catalyst is dichloro(1,3-bis(diphenylphosphino)propane)nickel(II).    TECHNOLOGY FOCUS - POLYMERS - Preparation (Claimed): A thiophene group-containing compound of formula (2) is reacted with a halo-containing compound of formula (3) in the presence of a metal catalyst, to obtain thiophene/phenylene co-oligomer of formula (4). A thiophene group-containing compound of formula (5) is reacted with a halo-containing compound of formula (6) in presence of the metal catalyst, to obtain thiophene/phenylene co-oligomer of formula (7). A phenyl/alkyl-containing compound of formula: Y3-B' (8) is reacted with a halo-containing compound of formula (9) in presence of the metal catalyst, to obtain thiophene/phenylene co-oligomer of formula (10).n,p=0 or 1;Y1-Y3=substituent in which cross-coupling of chloro, bromo or iodo is possible;andX1-X3=chloro, bromo or iodo.Preferred Polymer: The thiophene/phenylene co-oligomer (1) is preferably of formula (13). Preferred Method: The thiophene/phenylene co-oligomer of formula (13) is prepared by reacting a benzene-containing compound of formula (11) with a halo-containing compound of formula (12) in the presence of metal catalyst.Y4=Y1;andX4,X5=X1. EXAMPLE - Magnesium (in g) (0.88) and cyclopentyl methyl ether (15 ml) were added to a flask (100 ml), and a solution of 2-bromo-5-phenyl thiophene (7.9) and cyclopentyl methyl ether (15 ml) was then added in an amount of 1/10, under nitrogen atmosphere. The remaining amount of cyclopentyl methyl-ether solution of 2-bromo-5-phenyl thiophene was dripped for 1 hour and stirred, to obtain cyclopentyl methyl-ether solution of 5-phenyl-2- thienyl magnesium bromide. The obtained solution was dripped into a mixture of 2-(4-bromophenyl)-4-hexylthiophene (9.7), dichloro(1,3-bis(diphenylphosphino)propane)nickel(II) (0.81) and cyclopentyl methyl ether (60 ml) and stirred for 4 hours. Then, 2.5% hydrochloric acid (90 ml) was added, stirred for 30 minutes, heated, and liquid-separation was carried out. The separated organic layer was filtered, dried and purified using silica-gel column chromatography, to obtain 2-(4-(4-hexyl-2-thienyl)phenyl)-5-phenylthiophene (9.8) having melting point of 173 degrees C, with yield of 80%.