NOVELTY - A silyl-benzimidazolo(1,2-a)benzimidazole compound is new.    USE - New silyl-benzimidazolo(1,2-a)benzimidazole compound for electrophotographic photoreceptors, photoelectric converters, organic solar cells, switching elements, organic light emitting field effect transistors, image sensors, dye lasers, electroluminescent devices, stationary visual display units, mobile visual display units, illumination units, keyboards, items of clothing, furniture, and wallpaper (all claimed).    ADVANTAGE - The benzimidazole compound improves efficiency, stability, manufacturability, and spectral characteristics of electroluminescent devices.    DETAILED DESCRIPTION - A silyl-benzimidazolo(1,2-a)benzimidazole compound of formula (I) is new.    R1, R2, R4-R7=H, 1-25C alkyl optionally substituted by E1 and or interrupted by D1, or 2-6C heteroaryl optionally substituted by G1;    X1=H or group of formula (X1) or (X2);    X2, X3=H or group of formula (X3) or (X4);    R24=group of formula (R24a), (R24b), (R24c), or (R24d);    R41=group of formula (R41a), (R41b), or (R41c);    R42=H or group of formula (R42a);    R21, R21'=H, 1-15C alkoxy, 1-18C alkyl, or 1-18C alkyl interrupted by -O-, or group of formula (R21a);    R22, R25-R28, R25'-R28', R25''-R28'', R29, R29', R29'', R40, R43, R44=H, 1-18C alkoxy, 1-18C alkyl, or 1-18C alkyl interrupted by -O-;    D1=-CO-, -COO-, -S-, -SO-, -SO2-, -O-, -NR65-, -SiR70R71-, -POR72-, -CR63=CR64-, or -CC-;    E1=-CR69, -SR69, -NR65R66, -COR68, -COOR67, -CONR65R66, -CN, or halo;    G1=E1 or 1-18C alkyl, Ph, Ph optionally substituted by F, 1-18C alkyl, or 1-18C alkyl interrupted by O, 2-6C heteroaryl, or 2-6C heteroaryl substituted by F, 1-18C alkyl, or 1-18C alkyl interrupted by O;    R63, R64=H, Ph, Ph optionally substituted by 1-18C alkyl or 1-18C alkoxy, 1-18C alkyl, or 1-18C alkyl interrupted by -O-;    R65, R66=Ph, Ph substituted by 1-18C alkyl or 1-18C alkoxy, 1-18C alkyl or 1-18C alkyl interrupted by -O- in which R65 and R66 form a 5- or 6-membered ring;    R67=Ph, Ph substituted by 1-18C alkyl or 1-18C alkoxy, 1-18C alkyl or 1-18C alkyl interrupted by -O-;    R68=H, Ph, Ph substituted by 1-18C alkyl or 1-18C alkoxy, 1-18C alkyl or 1-18C alkyl interrupted by -O-;    R69=Ph, 6-18C aryl substituted by 1-18C alkyl or 1-18C alkoxy, 1-18C alkyl, 1-18C alkyl interrupted by -O-;    R70, R71=1-18C alkyl, Ph, or Ph substituted by 1-18C alkyl; and    R72=1-18C alkyl, Ph, or Ph substituted by 1-18C alkyl, provided that greater than or equal to 1 of X1, X2 and X2 is group of formula (XA) or (XB).    INDEPENDENT CLAIMS are included for:    (1) electronic device comprising compound of formula (I); and    (2) hole transport layer, electron or exciton blocking layer, or emitting layer comprising compound (I).