NOVELTY - Substituted azadibenzothiophene compounds (I) are new.    USE - (I) are useful: in electronic device which is electroluminescent device, and in apparatus comprising stationary visual display units, mobile visual display units, illumination units, keyboards, items of clothing, furniture and wallpaper; and in electrophotographic photoreceptors, photoelectric converters, organic solar cells, switching elements, organic light emitting field effect transistors, image sensors, dye lasers and electroluminescent devices (all claimed).    ADVANTAGE - (I) provide electronic device that exhibit improved efficiency, stability, manufacturability, or spectral characteristics of electroluminescent devices, and exhibit good durability.    DETAILED DESCRIPTION - Substituted azadibenzothiophene compounds of formula (I) are new.    B1 = N, or CR81;    B2 = N, or CR82;    B3 = N, or CR83;    B4 = N or CR84;    B5 = N or CR85;    B6 = N or CR86;    B7 = N or CR87;    B8 = N, or CR88;    R81-R88 = H, F, CN, 1-25C alkyl optionally substituted by E and or interrupted by D, 1-25C alkoxy, 3-18C cycloalkyl optionally substituted by E, 6-24C aryl optionally substituted by G, 2-30C heteroaryl optionally substituted by G or (A1 )o-(A2)p-(A3)q-(A4)rR16;    o, p , q, r = 0 or 1;    A1-A4 = 6-24C arylene optionally substituted by G, or 2-30C heteroarylene optionally substituted by G;    R16 = -NR10R11, or -Si(R12)(R13)(R14), 6-24C aryl optionally substituted by G or 2-30C heteroaryl optionally substituted by G;    R10, R11 = 6-24C aryl optionally substituted by G or 2-30C heteroaryl optionally substituted by G;    R12-R14 = 1-25C alkyl optionally substituted by E or interrupted by D, 6-24C aryl optionally substituted by G or 2-30C heteroaryl optionally substituted by G;    D = -CO-, -COO-, -S-, -SO-, -SO2-, -O-, -NR65-, -SiR70R71-, -POR72-, -CR63=CR64-, or -CC-;    E = -OR69, -SR69, -NR6R66, -COR68, -COOR6, -CONR6R66, -CN, or F;    G = E, or 1-18C alkyl, 3-18C cycloalkyl, 6-24C aryl (optionally substituted by F), 1-18C alkyl (optionally interrupted by O), 2-30C heteroaryl (optionally substituted by F), 1-18C alkyl (optionally interrupted by O);    R63, R64 = H, 6-18C aryl (optionally substituted by 1-18C alkyl or 1-18C alkoxy), 1-18C alkyl (optionally interrupted by O); either    R65, R66 = 6-18C aryl (optionally substituted by 1-18C alkyl or 1-18C alkoxy), 1-18C alkyl (optionally interrupted by O); or    R65R66 = five or six membered ring;    R67 = 6-18C aryl (optionally substituted by 1-18C alkyl or 1-18C alkoxy), 1-18C alkyl (optionally interrupted by O);    R68 = H, 6-18C aryl (optionally substituted by 1-18C alkyl or 1-18C alkoxy), 1-18C alkyl (optionally interrupted by O);    R69 = 6-18C aryl (optionally substituted by 1-18C alkyl or 1-18C alkoxy), 1-18C alkyl (optionally interrupted by O);    R70, R71 = 1-18C alkyl, 6-18C aryl, or 6-18C aryl substituted by 1-18C alkyl; and    R72 = 1-18C alkyl, 6-18C aryl (optionally substituted by 1-18C alkyl).    Provided that at least one of B1, B2, B3, B4, B, B6, B and B8 represents N; not more than two of the groups B1, B2, B3 and B4 represent N; and not more than two of the groups B5-B8 represent N; and with the further proviso that at least one of the substituents R81-R88 represent (A1)o-(A2)p-(A3)q-(A4)rR16, where R16 is benzimidazo(1,2-a)benzimidazo-5-yl optionally substituted by G and/or at least one of A1-A4 respresents a benzimidazo(1,2-a)benzimidazo-2,5-ylene group which is optionally substituted by G. An INDEPENDENT CLAIM is also included for a hole transport layer, electron transport layer, hole blocking layer, electron blocking layer, or emitting layer comprising (I).