NOVELTY - A polymer comprising one or more divalent units (I) is new.    USE - Polymer used as charge transport, semiconducting, electrically conducting, photoconducting or light emitting material in optical, electrooptical, electronic, electroluminescent or photoluminescent components or devices. Component or device is organic field effect transistors (OFET), thin film transistors (TET), integrated circuits (IC), logic circuits, capacitors, radio frequency identification (RFID) tags, devices or components, organic light emitting diodes (OLED), organic light emitting transistors (OLET), flat panel displays, backlights of displays, organic photovoltaic devices (OPV), organic solar cells (O-SC), photodiodes, laser diodes, photoconductors, photodetectors, electrophotographic devices, electrophotographic recording devices, organic memory devices, sensor devices, charge injection layers, charge transport layers or interlayers in polymer light emitting diodes (PLED5), Schottky diodes, planarizing layers, antistatic films, polymer electrolyte membranes (PEM), conducting substrates, conducting patterns, electrode materials in batteries, alignment layers, biosensors, biochips, security markings, security devices, and components or devices for detecting and discriminating DNA sequences.    ADVANTAGE - The polymer is easy to synthesize, especially by methods suitable for mass production. It also exhibits good processibility, high stability, good solubility in organic solvents, high charge carrier mobility, and low bandgap.    DETAILED DESCRIPTION - Polymer comprising one or more divalent units of formula (I) is new.    X1, X2=O or S; and    R1, R2=H, halo, or optionally substituted carbyl or hydrocarbyl group, where one or more C atoms are optionally replaced by hetero atom.    INDEPENDENT CLAIMS are included for:    (1) mixture or blend comprising the above polymers and one or more compounds or polymers having semiconducting, charge transport, hole/electron transport, hole/electron blocking, electrically conducting, photoconducting or light emitting properties; and    (2) formulation comprising one or more polymers, mixtures or blends, and one or more solvents, preferably selected from organic solvents; and    (3) process of preparing the polymer.