NOVELTY - A conjugated polymer comprising benzothiophene divalent unit(s) (I), is new.    USE - New conjugated polymer is used for mixture or polymer blend, and composition used as charge transport, semiconducting, electrical conducting, photoconducting or light emitting material for device such as organic field effect transistors, thin film transistors, organic light emitting diodes, organic light emitting transistors, organic photovoltaic devices e.g. bulk heterojunction organic photovoltaic device or inverted bulk heterojunction organic photovoltaic device, organic solar cells, laser diodes, Schottky diodes, photoconductors and photodetectors, components such as charge injection layers, charge transport layers, interlayers, planarizing layers, antistatic films, polymer electrolyte membranes, conducting substrates and conducting patterns, and assembly such as integrated circuits, radio frequency identification tags, security markings or security devices, flat panel displays or backlights, electrophotographic devices, electrophotographic recording devices, organic memory devices, sensor devices, biosensors and biochips (all claimed).    ADVANTAGE - The new conjugated polymer comprising benzothiophene divalent unit(s), has semiconducting property, charge transport property, hole/electron transport property, hole/electron blocking property, electrically conducting property, photoconducting property and light emitting properties.    DETAILED DESCRIPTION - A conjugated polymer comprising benzothiophene divalent unit(s) of formula (I), is new.    X1-X3,X=O or S;    R1,R2=linear, branched or cyclic 1-20C alkyl, in which non-adjacent carbon atom(s) are optionally replaced by -O-, -S-, -C(O)-, -C(S)-, -C(O)-O-, -C(S)-O-, - C(S)-S-, -C(O)-S-, -O-C(O)-, -O-C(S)-, -S-C(S)-, -S-C(O)-, - CH=CH- or -CC- and optionally substituted by F, CI, Br, I or CN;and    R3,R4=H, halo or optionally substituted carbyl or hydrocarbyl in which one or more carbon(s) are optionally replaced by heteroatom.    INDEPENDENT CLAIMS are included for the following:    (1) mixture or polymer blend, which comprises conjugated polymer comprising benzothiophene divalent unit(s) (I) and one or more compounds or polymers having semiconducting, charge transport, hole/electron transport, hole/electron blocking, electrically conducting, photoconducting or light emitting properties;    (2) composition, which comprises conjugated polymer comprising benzothiophene divalent unit(s), mixtures or polymer blends, and solvent(s), preferably organic solvents;    (3) benzothiophene-type monomer of formula: R5-(Ar1)a-U'-(Ar2)b-R6 (a); and    (4) preparation of polymer having benzothiophene divalent unit(s).    R5,R6=Cl, Br, I, O-tosylate, O-triflate, O-mesylate, O-nonaflate, -SiMe2F, -SiMeF2, -O-SO2Z1, -B(OZ2)2 , -CZ3=C(Z3)2, -CCH, - CCSi(Z1)3, -ZnX0 or -Sn(Z4)3;    X0=Cl, Br or I;    Z1-Z4=alkyl and aryl (both optionally substituted);and    or two of Z2=ring.