NOVELTY - Polymer (A) comprising fused benzo compound (I), is new.    USE - The polymers are useful as charge transport, semiconducting, electrically conducting, photoconducting or light emitting material in optical, electro optical, electronic, electroluminescent or photoluminescent components or devices, where the component or device includes organic field effect transistors, thin film transistors, integrated circuits, logic circuits, capacitors, radio frequency identification tags, devices or components, organic LED, organic light emitting transistors, flat panel displays, backlights of displays, organic photovoltaic devices, solar cells, laser diodes, photoconductors, photodetectors, electrophotographic devices, electrophotographic recording devices, organic memory devices, sensor devices, charge injection layers, charge transport layers or interlayers in polymer LED, schottky diodes, planarizing layers, antistatic films, polymer electrolyte membranes, conducting substrates, conducting patterns, electrode materials in batteries, alignment layers, biosensors, biochips, security markings, security devices, or components or devices for detecting and discriminating DNA sequences.    ADVANTAGE - The polymers have improved bandgap, charge carrier mobility, solubility, processability, oxidative stability and long life time, and are easily synthesizing in an economical manner.    DETAILED DESCRIPTION - Polymer (A) comprising fused benzo compound of formula (I), is new.    W1 = S, Se, O or NRX;    E1, E2 = -O-C(O)- or -C(O)-O-;    Rx = H or 1-30C alkyl, in which one or more non-adjacent C atoms are optionally replaced by -O-, -S-, -C(O)-, -C(O)-O-, -O-C(O)-, O-C(O)-O-, -CH=CH- or -C=C-, and one or more H atoms are optionally replaced by F, Cl, Br, I or CN;    U1 = not defined; and    R1, R2 = 1-40C carbyl or hydrocarbyl (both optionally substituted).    INDEPENDENT CLAIMS are included for:    (1) a mixture or blend comprising (A);    (2) a formulation comprising (A), mixtures or blends, and one or more solvents, preferably organic solvents;    (3) monomer having a structure of formula (R4-Ar1-U1-Ar2-R5) (Ia); and    (4) the preparation of (A).