NOVELTY - Heterocyclic compounds (I)-(III) are new.    USE - (I)-(III) or the oligomers, polymers or dendrimers are useful as a hole transport material in a hole transport layer or a hole injection layer, as a matrix material in an emitting layer and/or as an electron transport material in an electron transport layer of electronic devices, preferably organic electroluminescent devices comprising organic integrated circuits, organic field-effect transistors, organic thin film transistors, organic light emitting transistors, organic solar cells, organic optical detectors, organic photoreceptors, organic field-quench devices, light-emitting electrochemical cells, organic laser diodes and organic electroluminescent devices (all claimed).    ADVANTAGE - (I)-(III): is thermally stable; exhibits good power efficiencies, low operating voltages and high oxidation stability; and is producible with high purity. The organic electroluminescent devices containing (I)-(III) exhibit long service life.    DETAILED DESCRIPTION - Heterocyclic compounds of formulae (I)-(III) are new.    Z = CR2 or N;    X, Y1 = divalent group, preferably BR2, C(R2)2, C=O, C=NR2, C=C(R2)2, C=S, Si(R2)2, NR1, PR2, P(=O)R2, O, S, S=O or S(=O)2;    R1 = (hetero)aromatic ring with 5-60 aromatic ring atoms (optionally substituted by at least one group R3 and is optionally bonded with R2 at the backbone or an atom of the backbone); either    R2 = 1-20C alkoxy, 1-20C (thio)alkyl (both linear), 3-20C alkoxy, 3-20C (thio)alkyl (both branched or cyclic), 2-20C alkenyl, 2-20C alkynyl (in all groups at least one adjacent or non-adjacent CH2 group may be replaced by -R3C=CR3-, -CC-, Si(R3)2, Ge(R3)2, Sn(R3)2, C=O, C=S, C=Se, C=NR3, -C(=O)O-, -C(=O)NR3-, NR3, P(=O)(R3), -O-, -S-, SO or SO2 and in all groups at least one H may be replaced by D, F, Cl, Br, I, CN or NO2), (hetero)aromatic ring with 5-60 aromatic ring atoms, (hetero)aryloxy with 5-60 aromatic ring atoms (all optionally substituted by at least one group R3), H, D, F, Cl, Br, I, B(OR3)2, CHO, C(=O)R3, CHR3=C(R3)2, CN, C(=O)OR3, C(=O)N(R3)2, Si(R3)3, N(R3)2, N(A1)2, NO2, P(=O)(R3)2, OSO2R3, OR3, S(=O)R3 or S(=O)2R3; or    at least 2R2 = ring; either    R3 = 1-20C alkoxy, 1-20C (thio)alkyl (both linear), 3-20C alkoxy, 3-20C (thio)alkyl (both branched or cyclic), 2-20C alkenyl, 2-20C alkynyl (in all groups at least one adjacent or non-adjacent CH2 group may be replaced by -R4C=CR4-, -CC-, Si(R4)2, Ge(R4)2, Sn(R4)2, C=O, C=S, C=Se, C=NR4, -C(=O)O-, -C(=O)NR4-, NR4, P(=O)(R4), -O-, -S-, SO or SO2 and in all groups at least one H may be replaced by D, F, Cl, Br, I, CN or NO2), (hetero)aromatic ring with 5-60 aromatic ring atoms, (hetero)aryloxy with 5-60 aromatic ring atoms (all optionally substituted by at least one group R4), H, D, F, Cl, Br, I, B(OR4)2, CHO, C(=O)R4, CHR4=C(R4)2, CN, C(=O)OR4, C(=O)N(R4)2, Si(R4)3, N(R4)2, NO2, P(=O)(R4)2, OSO2R4, OR4, S(=O)R4 or S(=O)2R4; or    at least 2R3 = ring; either    R4 = 1-20C aliphatic organic group, 1-20C (hetero)aromatic organic group (in both groups at least one H atom may be replaced by D or F), H, D and/or F; or    at least 2R4 = ring; and    A1 = (hetero)aromatic ring with 5-30 aromatic ring atoms (optionally substituted by at least one group R3).    INDEPENDENT CLAIMS are also included for:    (1) preparing (I)-(III);    (2) an oligomer, polymer or a dendrimer comprising at least one compound (I)-(III), where the bonds to the polymer, oligomer or the dendrimer may be localized at arbitrary positions in (I)-(III) that is substituted with R1 or R2; and    (3) a formulation comprising (I)-(III) or at least one above polymer, oligomer or dendrimer, and at least one solvent.