NOVELTY - Polymer comprising at least one unit of substituted indacenodibenzothiophene compounds (I) is new.    USE - The polymer, mixture, polymer blend or formulation is useful as charge transport, semiconducting, electrically conducting, photoconducting or light emitting material in optical, electrooptical, electronic, electroluminescent or photoluminescent device, or its component, or in assembly comprising such a device or component, where the device is organic FETs, thin film transistors, organic LEDs, organic light emitting transistors, organic photovoltaic devices, organic photodetectors, organic solar cells, laser diodes, Schottky diodes, and photoconductors, the component is charge injection layers, charge transport layers, interlayers, planarizing layers, antistatic films, polymer electrolyte membranes, conducting substrates, conducting patterns, and the assembly is integrated circuits, radio frequency identification tags or security markings or security devices containing them, flat panel displays or backlights, electrophotographic devices, electrophotographic recording devices, organic memory devices, sensor devices, biosensors and biochips, bulk heterojunction (BHJ) photovoltaic device or inverted BHJ OPV device (all claimed).    ADVANTAGE - (I): have mesogenic or liquid crystalline properties and forms oriented anisotropic film that are useful as alignment layers to induce or enhance alignment in a liquid crystal medium provided onto the anisotropic film; The polymer: provides organic semiconducting materials at low cost and the materials showing good processability, high stability, good solubility in organic solvents, high charge carrier mobility and low bandgap.    DETAILED DESCRIPTION - Polymer comprising at least one unit of substituted indacenodibenzothiophene compounds of formula (I) is new.    X1, X2 = C(R1R2) or C=C(R1R2) (both preferred), Si(R1R2) or C=O;    A1 = benzothiophene-2,6,7-triyl, benzothiophene-2,4,5-triyl or benzothiophene-2,5,6-triyl, where thiophene ring is optionally substituted in 3-position by R1;    A2 = benzothiophene-2,6,7-triyl, benzothiophene-2,4,5-triyl or benzothiophene-2,5,6-triyl where thiophene ring is optionally substituted in 3-position by R1;    B1 = phenylene or thieno(3,2-b)thiophene-2,3,5,6-tetrayl;    R1, R2 = H, straight-chain, branched or cyclic 1-30C alkyl in which at least one non-adjacent CH2 is is optionally replaced by -O-, -S-, -C(O)-, -C(S)-, -C(O)-O-, -O-C(O)-, -NR10-, -SiR10R110-, -CF2-, -CHR10CR110-, -CY1=CY2- or -CC- in such a manner that O and/or S atoms are not linked directly to one another, and in which at least one H is optionally replaced by halo or CN, aryl, heteroaryl, aryloxy or heteroaryloxy with 4-20C ring atoms which is optionally substituted by halo or at least one alkyl or cyclic alkyl;    Y1, Y2 = H, F, Cl or CN; and    R10, R110 = H or optionally substituted 1-40C carbyl or hydrocarbyl, preferably 1-12C alkyl.    INDEPENDENT CLAIMS are also included for:    (1) preparing the polymer;    (2) a mixture or polymer blend comprising (I) and at least one compound or polymer having semiconducting, charge transport, hole/electron transport, hole/electron blocking, electrically conducting, photoconducting or light emitting properties;    (3) a formulation comprising at least one the polymer, the mixture or polymer blend, and at least one solvent, preferably organic solvent; and    (4) a monomer of formula (R7-(Ar1)a-U1-(Ar2)c-R8) (VI).    R7, R8 = Cl, Br, I, O-tosylate, O-triflate, O-mesylate, O-nonaflate, -Si-(CH3)2F, -Si-(CH3)F2, -O-SO2Z1, -B(OZ2)2 , -CZ3=C(Z3)2, -CCH, -CCSi(Z1)3, -ZnX1z or -Sn(Z4)3; either    Z1-Z4 = alkyl or aryl (both optionally substituted; or    Z2Z2 = cyclyl; and    X1z = halo, preferably Cl, Br or I.