NOVELTY - Polymer comprising substituted 2,7-pyrene-diyl structural units (I), is new.    USE - The polymer or the mixture is useful in at least one active layer of an organic electronic device, preferably an organic electroluminescent device (organic light-emitting diode) (preferred), organic light-emitting electrochemical cell, organic integrated circuit, organic field-effect transistor, organic thin-film transistor, organic solar cell, organic laser diode, organic photovoltaic element or organic photovoltaic device and an organic photoreceptor (all claimed).    ADVANTAGE - The polymer exhibits large band gap which achieves a deeper blue singlet emission for display applications with large color space, and increases service life, efficiency and quality of the organic electroluminescent devices.    DETAILED DESCRIPTION - Polymer comprising substituted 2,7-pyrene-diyl structural units of formula (I), is new.    R1 = 1-40C alkyl or 1-40C (thio)alkoxy (both linear) or 3-40C alkyl or 3-40C (thio)alkoxy (both branched or cyclic) (in all groups at least one H is optionally replaced by R2, and at least one non-adjacent CH2 group is optionally replaced by O, S, Si(R2)2, Ge(R2)2, BR2, NR2, PR2, CO, C=S, C=Se, C=NR2, PO(R2), PS(R2), R2C=CR2, CC, SO, SO2, COO, O(CO)O or CONR2), mono- or polycyclic and (hetero)aromatic ring, H, D, F, Cl, Br, I, OH or N(R2)2; and    R2 = 1-40C alkyl or 1-40C (thio)alkoxy (both linear) or 3-40C alkyl or 3-40C (thio)alkoxy (both branched or cyclic) (in all groups at least one H is optionally replaced by F, and at least one non-adjacent CH2 group is optionally replaced by O, CO, COO or O(CO)O), mono- or polycyclic and (hetero)aromatic ring, H or F.    INDEPENDENT CLAIMS are also included for:    (1) substituted pyrene compounds of formula (II);    (2) a mixture comprising the above polymer and additionally polymeric-, oligomeric-, dendritic- or low molecular weight substances; and    (3) a formulation comprising the polymer and at least one solvent.    X = leaving group suitable for polymerization reaction.