NOVELTY - Polymer (A) containing 0.01-100 mol.% of one or more substituted thiophene or furan structural units (I) and/or (II), is new.    USE - (A), blends or solution is useful in organic electronic device, which is organic- or polymeric light emitting diode (OLED, PLED) organic integrated circuits, organic field-effect transistors, organic thin-film transistors, organic solar cells, organic laser diodes, organic photovoltaic elements or devices, and organic photoreceptors, preferably PLED (all claimed). (A) is useful as semiconductors.    ADVANTAGE - (A) exhibits improved efficiency and a longer lifetime, particularly when used in OLED.    DETAILED DESCRIPTION - Polymer (A) containing 0.01-100 mol.% of one or more substituted thiophene or furan structural units of formula (I) and/or (II), is new.    Either R1-R10 = H, halo (F, Cl, Br or I), CN, NO2, NCS, NCO, OCN, SCN, SF5, Si(R)3, 1-22C alkyl or 1-22C alkoxy, where in alkyl- or alkoxy group, one or more non-adjacent carbon atoms can be replaced by C(R)=C(R), C?=C, N(R), O, S, CO, CO-O, O-CO or O-CO-O, and one or more H atoms can be replaced by 5-40C (hetero)aryl or 5-40C hetero(aryloxy) (both optionally substituted by one or more non-aromatic groups of R1-R10) or F; or    two or more radicals of R1-R10 = aliphatic or aromatic, mono- or polycyclic ring system, or condensed-ring system (with benzene or thiophene ring in (I) and/or (II));    R = H, halo or 1-22C alkyl (in which one or more non-adjacent carbon atoms can be replaced by O, S, CO, CO-O, O-CO or O-CO-O, and one or more H atoms can be replaced by 5-40C (hetero)aryl or 5-40C hetero(aryloxy) (both optionally substituted by one or more non-aromatic groups of R1-R10) or F); and    X = S or O, where at least one of R1-R10 denotes the link in the polymer.    INDEPENDENT CLAIMS are included for:    (1) the preparation of (A);    (2) substituted thiophene or furan compounds (I) and (II), which are copolymerize under conditions of C-C or C-N linking reactions;    (3) mixtures (blends) of one or more polymer with another polymeric, oligomeric, dendritic and/or low molecular weight substances;    (4) solutions and formulations of one or more polymer or blends in one or more solvents; and    (5) organic electronic device with one or more active layers, where at least one of these active layers contains one or more polymers or blends.    Two of R1-R10 = functional groups comprising Cl, Br, I, O-tosylate, O-triflate, O-SO2R22, B(OR22)2 or Sn(R22)3; and either    R22 = H, or aliphatic or aromatic 1-20C hydrocarbon radical; or    two or more of R22 = ring system.