TECHNOLOGY FOCUS - POLYMERS - Preparation (disclosed): The new polymer containing fused selenophene ring is obtained by carrying out co-polymerization between boronic ester or organotin reagent of selenopheno(3,2-b)thiophene and selenopheno(3,2-b)selenophene with an aromatic dibromide or diiodide, in the presence of a palladium catalyst and a phosphine ligand. Preferred Polymer: The polymer containing fused selenophene ring is preferably of formula (2), more preferably polymer chosen from 24 compounds such as of formulae (3-7).R1,R2,X1,X2,Ar,m,n,P',Sp=as mentioned above;R3,R4=R1, -CH2Cl, -CHO, -CH=CH2-SiR'R"R"', -SnR'R"R"', -BR'R", -B(OR')(OR"), -B(OH)2, or P'-Sp;R',R",R"'=R0;andR=R1.R' and R" may also form a ring together with the hetero atom to which they are attached. Preferred Composition: A polymer blend is obtained using the polymer containing fused selenophene ring, and polymer(s) chosen from polymers having semiconducting, charge transport, hole/electron transport, hole/electron blocking, electrically conducting, photoconducting or light-emitting properties. A formulation is obtained using the polymer blend and organic solvent(s). Preferred Definitions:    m=1;    Ar=selenophene-2,5-diyl, thiophene-2,5-diyl, thieno(3,2-b)thiophene-2,5-diyl, thieno(2,3-b)thiophene-2,5-diyl, selenopheno(3,2-b)selenophene-2,5-diyl, selenopheno(2,3-b)selenophene-2,5-diyl, selenopheno(3,2-b)thiophene-2,5-diyl, selenopheno(2,3-b)thiophene-2,5-diyl, 1,4-phenylene, pyridine-2,5-diyl, pyrimidine-2,5-diyl, p-p'-biphenyl, naphthalene-2,6-diyl, benzo(1,2-b:4,5-b')dithiophene-2,6-diyl, 2,2-dithiophene, 2,2-diselenophene, thiazole, or oxazole, all of which are unsubstituted, mono- or polysubstituted by R1;    Ar=-CH=CH- or -C?=C-;and    R1,R2=straight-chain, 1-20C alkyl, 1-20C alkoxy, 2-20C alkenyl, 2-20C alkynyl, 1-20C thioalkyl, 1-20C silyl, 1-20C ester, 1-20C amino, 1-20C fluoroalkyl, or optionally substituted (hetero)aryl.    EXAMPLE - To a solution of selenopheno(3,2-b)thiophene (in g) (1.01) in anhydrous tetrahydrofuran (30 ml) was added butyl lithium solution (1.6 M in hexane, 7.5 mL) dropwise at -78 degrees C. The mixture was stirred for 1 hour, and 2-isopropoxy-4,4,5,5-tetramethyl-(1,3,2)dioxaborolane (2.24) was added. The resultant mixture was allowed to warm to 23 degrees C and stirred overnight. The reaction mixture was poured into saturated ammonium chloride solution and stirred for 10 minutes, then extracted with ethyl acetate (3x 30 mL). The combined extracts were washed with water and brine, and dried over sodium sulfate. The solvent was removed under reduced pressure to give off-white solid, which was re-crystallized with tetrahydrofuran/acetonitrile, to afford 2,5-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)selenopheno(3,2-b)thiophene as white crystals (0.73) with a yield of 31%. 2,5-Bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)selenopheno(3,2-b)thiophene (0.25) and 5,5'-dibromo-4,4'-dihexadecyl-2,2'-bithiophene (0.43) were dissolved in toluene (10 mL). Tris(dibenzylideneacetone)dipalladium (0) (6.4 mg), tris(t-butyl)phosphine-tetrafluoroborate (7.6 mg) and Aliquat 336 (RTM: N-methyl-N,N-dioctyloctan-1-aminium chloride) (0.5). The reaction mixture was degassed (via bubbling nitrogen) with stirring. A degassed solution of potassium carbonate (2 mL) was added via syringe to the stirred reaction mixture. The resultant mixture was heated at reflux and stirred for 20 hours. After cooling to 23 degrees C, the reaction mixture was precipitated from a mixture of 37% hydrochloric acid (2 mL) and methanol (50 mL) and stirred for 10 minutes. The precipitate was filtered off and washed with water and acetone, to give a crude polymer. The crude polymer was further purified by washing via Soxhlet extraction with methanol for 5 hours, acetone for 15 hours and iso-hexane for 7 hours before drying in vacuo. The polymer was dissolved in hot chlorobenzene (10 mL) and precipitated from methanol (50 mL). The polymer was collected by filtration, washed with acetone, and dried in vacuo to yield poly(5,5'-(4,4'-dihexadecyl(2,2')bithiophene)-co-(selenopheno(3,2-b)thiophene)) as a dark red solid (0.37) with a yield of 82%. The polymer had a number average molecular weight of 29300 g/mol and a weight average molecular weight of 73500 g/mol.