TECHNOLOGY FOCUS - ELECTRONICS - Preferred Components: The emitting layer comprises (I) as host material in combination with a phosphorescent emitter.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (Disclosed): Preparation of (I) comprises reacting 9-(8-(4,4,5,5-tetramethyl-(1,3,2)dioxaborolan-2-yl)-dibenzofuran-2-yl)-9H-4b,9,10-triaza-indeno(1,2-a)indene with substituted 2-chloro-(1,3,5)triazine compounds of formula (p1) in the presence of tetrakis(triphenylphosphine)palladium(0) to obtain substituted 9-(8-(1,3,5)triazin-2-yl-dibenzofuran-2-yl)-9H-4b,9,10-triaza-indeno(1,2-a)indene compounds of formula (p2) (representative of (I)). Preferred Definitions:    A1 = 1,3,5-benzen-triyl, 3,5,3'-biphenyl-triyl or dibenzofuran-2,4,8-triyl;    A2, A3 = 1,3-phenylene or dibenzofuran-2,8-diyl;    R9R10, R9aR10a = substituted phenyl moiety of formula (d1) or (d2);    R2-R5, R11-R14 = H;    R1, R1a = phenyl, 2,4,6-trimethyl-phenyl, 2,4-dimethyl phenyl, carbazol-9-yl, 9H-4b,9,10-triaza-indeno(1,2-a)indenyl, 9-dibenzofuran-2-yl-9H-4b,9,10-triaza-indeno(1,2-a)indenyl, dibenzofuran-2-yl, dibenzofuran-4-yl or substituted 9H-carbazole moiety of formula (d3); and    R16 = 6-18C aryl (optionally substituted with 1-18C alkyl).    SPECIFIC COMPOUNDS - 79 Compounds (I) are specifically claimed e.g. 9-(4,6-diphenyl-(1,3,5)triazin-2-yl)-9H-4b,9,10-triaza-indeno(1,2-a)indene of formula (Ia), 9-(4,6-bis-(2,4-dimethyl-phenyl)-(1,3,5)triazin-2-yl)-9H-4b,9,10-triaza-indeno(1,2-a)indene, 9-(8-(4,6-diphenyl-(1,3,5)triazin-2-yl)-dibenzofuran-2-yl)-9H-4b,9,10-triaza-indeno(1,2-a)indene, 9-(8-(4,6-bis-(2,4,6-trimethyl-phenyl)-(1,3,5)triazin-2-yl)-dibenzofuran-2-yl)-9H-4b,9,10-triaza-indeno(1,2-a)indene and 9-(3-(8-(4,6-diphenyl-(1,3,5)triazin-2-yl)-dibenzofuran-2-yl)-phenyl)-9H-4b,9,10-triaza-indeno(1,2-a)indene.    EXAMPLE - n-Butyl lithium (9.7 ml) in hexane was added to 6H-benzimidazolo(1,2-a)benzimidazole (5 g) in water free tetrahydrofuran (THF) (100 ml) at -78 degrees C under argon. The resulting reaction mixture was stirred for 15 minutes and warmed to -25 degrees C. The reaction mixture was cooled to 0 degrees C. 2-chloro-4,6-diphenyl-1,3,5-triazine was in THF (50 ml) was added, stirred for 15 minutes at 0 degrees C and heated under argon at 60 degrees C for 24 hours. The resulting product was filtered, washed and worked up to give 9-(4,6-diphenyl-(1,3,5)triazin-2-yl)-9H-4b,9,10-triaza-indeno(1,2-a)indene (79%).