NOVELTY - Hetero-spirobifluorene compounds (I) are new.    USE - (I) are useful: in oligomer, dendrimer, polymer and formulation; in an electronic device preferably organic electroluminescent devices (preferred), 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 and organic laser diodes; and in a layer of hole transport layers together p-dopants and emitting layer together with phosphorescent emitters (all claimed).    DETAILED DESCRIPTION - Hetero-spirobifluorene compounds of formula (I) are new.    A=C or Si;    Y1=N or P;    X1=N or CR1;    Ar1-Ar6=6-40C aromatic ring or 5-40C heteroaromatic ring (all optionally substituted with R2);    R2=straight-chain alkyl or alkoxy having 1-20C, branched or cyclic alkyl or alkoxy having 3-20C, alkenyl or alkynyl having 2-20C, 6-40C aromatic ring, 5-40C heteroaromatic ring (all optionally substituted with R3) (where at least two R1 and R2 are fused joined together to form a ring, and at least one CH2 group in the alkyl, alkoxy, alkenyl and alkynyl groups is optionally replaced with -R3C=CR3, -C(C)-, Si(R3)2, C=O, C=NR3, -C(O)O-, -C(O)NR3-, NR3, P(O)(R3), -O-, -S-, SO or SO2), H, D, F, C(=O)R3, CF3, OCF3, CN, Si(R3)3, N(R3)2, P(O)(R3)2, OR3, S(O)R3 or SO2R3;    R3=straight-chain alkyl or alkoxy having 1-20C, branched or cyclic alkyl or alkoxy having 3-20C, alkenyl or alkynyl having 2-20C, 6-40C aromatic ring, 5-40C heteroaromatic ring (all optionally substituted with R4) (where at two R are fused together to form a ring, and at least one CH2 group in the alkyl, alkoxy, alkenyl or alkynyl groups is optionally replaced with -R4C=CR4-, -CC-, Si(R4)2, C=O, C=NR4, -C(O)O-, -C(O)NR4-, NR4, P(O)(R4), -O-, -S-, SO or SO2), H, D, F, C(O)R4, CF3, OCF3, CN, Si(R4)3, N(R4)2, P(O)(R4)2, OR4, S(O)R4 or SO2R4;    R4=1-20C alkyl, 60-40C aromatic ring, 5-40C heteroaromatic ring (both optionally substituted with F or CN), H, D, F or CN, where at least two R 4 are fused joined together to form a ring; and    a-d=0 or 1, preferably 1.    Provided that: at least two groups of Ar1 and Ar2 is 12-40C aromatic ring or 12-40C heteroaromatic ring (both optionally substituted with R2); and (I) comprise no arylamino group as a substituent. INDEPENDENT CLAIM is also included for:    (1) preparation of (I);    (2) oligomer, dendrimer or polymer comprising (I), where R1 or R2 position of (I) is bonded to the polymer, oligomer or dendrimer; and    (3) formulation comprising (I), or the oligomer, polymer or dendrimer, and at least one further compound and/or a solvent.