NOVELTY - Substituted azadibenzofuran compounds (I) are new.    USE - (I) are useful: in an electronic device which is used as an electroluminescent device; in a hole transport layer or an emitting layer which is used in an apparatus comprising stationary visual display units, mobile visual display units, illumination units, keyboards, items of clothing, furniture or wallpaper; and in electrophotographic photoreceptors, photoelectric converters, organic solar cells, switching elements, organic light emitting FET, image sensors or dye lasers (all claimed); and in organic LEDs, visual display units of computers and TV, visual display units in printers, kitchen appliances and advertising panels and information panels, and visual display units in cell phones, tablet personal computers, laptops, digital cameras, moving picture experts group 1 or 2 audio layer III (MP3) players, vehicles and destination displays on buses and trains.    ADVANTAGE - (I): provide improved efficiency, stability, manufacturability, or spectral characteristics of the electroluminescent device; exhibit a lowest unoccupied molecular orbital-level of 2-2.5 eV; exhibit excellent power efficiency, when (I) are used as host in combination with phosphorescent emitters; and provide electroluminescent devices with reduced drive voltage while maintaining excellent luminance properties.    DETAILED DESCRIPTION - Substituted azadibenzofuran 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 = 1-25C alkyl (optionally substituted by E1a and/or interrupted by D1a), 6-24C aryl (optionally substituted by G1a), 2-30C heteroaryl (optionally substituted by G1a), -(A1a)o-(A2a)p-(A3a)q- (A4a)r-R16 or H;    o, p, q and r = 0 or 1;    A1a-A4a = 6-24C arylene (optionally substituted by G1a) or 2-30C heteroarylene (optionally substituted by G1a);    R16 = 6-24C aryl (optionally substituted by G1a) or 2-30C heteroaryl (optionally substituted by G1a), -NR10R11 or -Si(R12)(R13)(R14);    R10, R11 = 6-24C aryl (optionally substituted by G1a) or 2-30C heteroaryl (optionally substituted by G1a);    R12-R14 = 1-25C alkyl (optionally substituted by E1a and/or interrupted by D1a), 6-24C aryl (optionally substituted by G1a) or 2-30C heteroaryl (optionally substituted by G1a);    D1a = -CO-, -COO-, -S-, -SO-, -SO2-, -O-, -NR65-, -SiR70R71-, -POR72-, -CR63=CR64- or -CC-;    E1a = -CR69, -SR69, -NR65R66, -COR68, -COOR67, -CONR65R66, -CN or F;    G1a = 6-24C aryl (optionally substituted by F or 1-18C alkyl (optionally interrupted by O)), 2-30C heteroaryl (optionally substituted by F or 1-18C alkyl (optionally interrupted by O)), E1a or 1-18C alkyl;    R63, R64 = 6-18C aryl (optionally substituted by 1-18C alkyl or 1-18C alkoxy), 1-18C alkyl (optionally interrupted by -O-) or H; either    R65, R66 = 6-18C aryl (optionally substituted by 1-18C alkyl or 1-18C alkoxy) or 1-18C alkyl (optionally interrupted by -O-); or    R65+R66 = 5 or 6 membered ring;    R67 = 6-18C aryl (optionally substituted by 1-18C alkyl or 1-18C alkoxy) or 1-18C alkyl (optionally interrupted by -O-);    R68 = 6-18C aryl (optionally substituted by 1-18C alkyl or 1-18C alkoxy), 1-18C alkyl (optionally interrupted by -O-) or H;    R69 = 6-18C aryl (optionally substituted by 1-18C alkyl or 1-18C alkoxy), 1-18C alkyl (optionally interrupted by -O-); and    R70-R72 = 6-18C aryl (optionally substituted by 1-18C alkyl) or 1-18C alkyl.    Provided that: at least one of B1-B8 is N, not more than two of B1-B4 are N, and not more than two of B5-B8 are N; at least one of R81-R88 are -(A1a)o-(A2a)p-(A3a)q-(A4a)r-R16, where R16 is benzimidazo(1,2-a)benzimidazo-5-yl (optionally substituted by G1a); and/or at least one of A1a-A4a is benzimidazo(1,2-a)benzimidazo-2,5-ylene (optionally be substituted by G1a). INDEPENDENT CLAIMS are also included for:    (1) substituted azadibenzofuran compounds of formula (II); and    (2) a hole transport layer, or an emitting layer comprising (I).    M1 = N or CQ81;    M2 = N or CQ82;    M3 = N or CQ83;    M4 = N or CQ84;    M5 = N or CQ85;    M6 = N or CQ86;    M7 = N or CQ87;    M8 = N or CQ88;    Q81-Q88 = 1-25C alkyl (optionally substituted by E1a and/or interrupted by D1a), 6-24C aryl (optionally substituted by G1a), 2-30C heteroaryl (optionally substituted by G1a), -(A1a)o-(A2a)p-(A3a)q- (A4a)r-R16, -(A1a)o-(A2a)p-(A3a)q- (A4a)r-X1 or H, where at least one of Q81-Q88 is -(A1a)o-(A2a)p-(A3a)q- (A4a)r-X1;    X1 = Cl, Br or I, ZnX12, -SnR207R208R209, -B(OH)2, -B(OY1)2, boron containing moiety of formula (k1) or (k2), BF4Na or -BF4K;    X12 = halo; either    R207-R209 = H or 1-8C alkyl; or    two of R207-R209 = optionally ring, where R207-R209 are optionally branched;    Y1 = 1-18C alkyl;    Y2 = 2-10C alkylene; and    Y13, Y14 = H or 1-18C alkyl.    Provided that (II) is not 3,6-dichloro-benzo(4,5)furo(2,3-b)pyridine, 2-chloro-3,4-diphenyl-benzo(4,5)furo(2,3-b)pyridine, 6-chloro-benzo(4,5)furo(2,3-b)pyridine, 3-chloro-benzo(4,5)furo(2,3-b)pyridine, 3-chloro-benzo(4,5)furo(3,2-c)pyridine, 1-chloro-benzo(4,5)furo(3,2-c)pyridine, 1,3,4-trichloro-benzo(4,5)furo(3,2-c)pyridine, 3,7-dibromo-furo(3,2-b;4,5-b')dipyridine, 2-chloro-benzo(4,5)furo(2,3-b)pyridine, 2,3,4-trichloro-benzo(4,5)furo(2,3-b)pyridine, 1-chloro-benzo(4,5)furo(2,3-c)pyridine, 8-bromo-benzo(4,5)furo(3,2-c)pyridine, 8-bromo-benzo(4,5)furo(3,2-b)pyridine, 8-chloro-benzo(4,5)furo(3,2-b)pyridine, 6-chloro-8-phenyl-benzo(4,5)furo(3,2-b)pyridine, 3-chloro-benzo(4,5)furo(3,2-b)pyridine, 8-(4,4,5,5-tetramethyl-(1,3,2)dioxaborolan-2-yl)-benzo(4,5)furo(3,2-b)pyridine, 7-chloro-benzo(4,5)furo(3,2-b)pyridine or 8-(3-bromo-phenyl)-benzo(4,5)furo(3,2-b)pyridine.