NOVELTY - A carbazole derivative (I), is new.    USE - New carbazole derivative is used as host material in mixture for composition (all claimed) used in formation of emitter layer of optoelectronic device. Uses include but are not limited to organic light-emitting diode, organic solar cell, organic transistor, light-emitting electrochemical cell, organic field effect transistor and organic laser.    ADVANTAGE - The new carbazole derivative has high triplet energy, excellent electrochemical stability, good stacking in the amorphous solid state and good charge transportability, and is economically prepared with reduced energy consumption.    DETAILED DESCRIPTION - A carbazole derivative of formula (I), is new.    A=acceptor with electron-withdrawing properties, chosen from pyridinyl, pyridazinyl, pyrimidinyl, pyrazinyl, triazinyl, oxazolyl, thiazolyl, imidazolyl, pyrazolyl, isoxazolyl, isothiazolyl, 1,2,3-triazolyl, 1,2,4-triazolyl, 1,2,4-oxadiazole, 1,2,4-thiadiazolyl, tetrazolyl, 1,2,3,4-oxatriazolyl, 1,2,3,4-thiatriazolyl, benzimidazolyl, benzoxazolyl or benzothiazolyl (all optionally substituted by P(=O)R12, P(=O)R1, P(=S)R12, P(=S)R1, P(=Se)R12, P(=Se)R1 or SO2);    D1=group of formula (i);    D2=group of formula (ii);    n=1-5;    o,p=1-4;    o+p=5 or less;    X=divalent group chosen from O, S, S=O, SO2, Se, Se=O, SeO2, C(R3)2, C=NR3, C=C(R3)2, Si(R3)2, N(R3), P(R3), P(=O)R3 or B(R3);    Y'=covalent single bond, or divalent group;    Z=CR2 or N;    R1=H, halo, D, -NR22, -OR2, alkynyl, or linear, branched or cyclic optionally substituted alkyl, heteroalkyl, aryl, heteroaryl or alkenyl (all optionally substituted by halo, deuterium or linear, branched or cyclic alkyl);    R2=H, D, alkynyl, or linear, branched or cyclic optionally substituted alkyl, heteroalkyl, aryl, heteroaryl or alkenyl (all optionally substituted by halo, deuterium or linear, branched or cyclic alkyl);    R3=H, D, OR5, SR5 or CR53;and    R5=H, alkyl or aryl.    INDEPENDENT CLAIMS are included for the following:    (1) preparation of compound (I);    (2) mixture, which comprises compound(s) (I) and luminescent emitter(s); and    (3) composition, which contains compound(s) (I) or mixture, and solvent(s).