TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (Disclosed): The preparation of (I), comprises performing Suzuki coupling reaction of compounds of formula (II) with halo substituted hetero(aromatic) compounds of formula (III) to obtain substituted heterocyclic compounds of formula (IV), performing bromination of (IV) using N-bromosuccinimide to obtain brominated heterocyclic compounds of formula (V), and performing Buchwald coupling of (V) with N-containing heterocyclic compounds of formula (VI) to obtain heterocyclic compounds of formula (VII), (i.e. representative of (I)).Z1 = Cl, Br or I; andX1, U1 = N or CR1, (where at least one of the five groups X1 in ring A is N, preferably three of the five groups X1), preferably 1,3,5-triazine.Preferred Components: The further compound is a host or matrix material. The further compound has band gap of greater than or equal to 2.5 eV, preferably greater than or equal to 3.5 eV. SPECIFIC COMPOUNDS - 149 Compounds (I) are disclosed, e.g. 9-(6-(4,6-diphenyl-1,3,5-triazin-2-yl)dibenzo(b,d)thiophen-2-yl)-9H-carbazole of formula (Ia), 9-(6-(4,6-diphenyl-1,3,5-triazin-2-yl)dibenzo(b,d)thiophen-2-yl)-3-phenyl-9H-carbazole, 9-(6-(4,6-diphenyl-1,3,5-triazin-2-yl)dibenzo(b,d)furan-2-yl)-3-phenyl-9H-carbazole, 9-(6-(4,6-diphenylpyrimidin-2-yl)dibenzo(b,d)furan-2-yl)-3-phenyl-9H-carbazole and 9-(6-(4-(dibenzo(b,d)furan-4-yl)-6-phenyl-1,3,5-triazin-2-yl)dibenzo(b,d)thiophen-2-yl)-3-phenyl-9H-carbazole.    EXAMPLE - Degassed solution of 70 g 2-(8-bromodibenzo(b,d)thiophen-4-yl)-4,6-diphenyl-1,3,5-triazine and 35.7 g 9H-carbazole was saturated with nitrogen in 600 ml toluene for 1 hour, 2.09 ml tri-tert-butylphosphine and 1.38 g palladium(II) acetate and 17.7 g sodium tert-butoxide in solid state were added, and heated under reflux for 1 hour to obtain reaction mixture. Then the mixture was cooled to room temperature, 500 ml water was added, layers were separated, an aqueous phase was washed with 150 ml toluene, dried over magnesium sulfate and the solvent was removed in vacuum to obtain a crude product. Then the crude product was purified by chromatography over silica gel using heptane and acetic ester at volume ratio of 20:1, residue was recrystallized from toluene and then sublimated under high vacuum to obtain 9-(6-(4,6-diphenyl-1,3,5-triazin-2-yl)dibenzo(b,d)thiophen-2-yl)-9H-carbazole with 95% yield.