NOVELTY - Polymer (A), comprising at least one (hetero)aryl-containing structural units (I), is new.    USE - (A) is useful as hole transport-, hole injection-, emitter-, electron transport-, electron injection-, charge blocking- and/or charge generating-layer(s) in electronic devices including electroluminescent devices (such as organic/polymer LED), organic integrated circuit, organic field effect transistor, organic thin film transistor, organic light emitting transistor, organic solar cells, organic optical detector, organic photoreceptor, organic field-quench device, light emitting electrochemical cell or organic laser diode. (II) is useful for preparing crosslinkable and/or crosslinked polymers (all claimed).    ADVANTAGE - (A): is easily crosslinkable (due to the presence of suitable functional groups for crosslinking) with low energy expenditure, where the crosslinking is carried out thermally or induced by radiation; has no negative effects on the function of the electronic devices; has good crosslinking properties thus allowing only fewer by-products to be formed during crosslinking; and exhibits very high stability.    DETAILED DESCRIPTION - Polymer (A), comprising at least one (hetero)aryl-containing structural units of formula (I), is new.    Z = (hetero)aryl ring system (optionally substituted with one or more R);    X = spacer group or a direct bond;    Ar1, Ar2 = (hetero)aryl (optionally substituted with one or more R) or bonded together;    Q = crosslinkable group;    R1 = linear 1-40C alkyl or thio(alkoxy), cyclic 3-40C alkyl or thio(alkoxy), silyl group, substituted 1-40C ketogroup, optionally substituted (hetero)aryl ring system having 5-60 ring atoms and/or (hetero)aryloxy having 5-60 ring atoms, or Ar2, where one or more H-atom(s) is/are optionally replaced with F; either    R = linear or branched 1-40C alkyl or (thio)alkoxy, or cyclic 3-40C alkyl or (thio)alkoxy (both optionally substituted with one or more R2, where one or more non-adjacent CH2 groups are replaced with R2C=CR2, C=C , Si(R2)2, Ge(R2)2, Sn(R2)2, C=O, C=S, C=Se, C=NR2, P(=O)(R2), SO, SO2, NR2, O, S or CONR2 and one or more H atom is replaced with F, Cl, Br, I, CN or NO2), 5-60 membered (hetero)aryl ring system (optionally substituted with one or more R2)5-60 membered (hetero)aryloxy (optionally substituted with one or more R2), F, Cl, Br, I, N(Ar)2, N(R2)2, CN, NO2, Si(R2)3, B(OR2)2, C(=O)Ar, C(=O)R2, P(=O)(Ar)2, P(=O)(R2)2, S(=O)Ar, S(=O)R2, S(=O)2Ar, S(=O)2R2, -CR2=CR2Ar and/or OSO2R2; or    two or more R = mono- or poly-cyclic, aliphatic or aromatic ring system;    R2 = H or 1-20C aliphatic or aromatic hydrocarbon; and    n = 1-4.    Where the dotted lines represent the linkage in the polymer, when n is 1, and when Z is F and n is 2 then X is not a direct bond. INDEPENDENT CLAIMS are included for:    (1) (hetero)aryl-containing compounds of formula (II);    (2) a formulation comprising the polymer in one or more solvents; and    (3) an electronic device comprising the polymer.    Y1, Y2 = leaving groups (preferably halide, boric acid or its ester, boran, mesitylate or triflate).