TECHNOLOGY FOCUS - ELECTRONICS - Preferred Layers: The organic thin-film layer is light-emitting layer (130), hole-transport layer, hole-injection layer, hole-blocking layer, electron-transport layer, electron-injection layer, and/or electron-blocking layer. The organic thin-film layer contains a phosphorescent dopant chosen from red, green and blue dopants.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation: No general preparation given. Preferred Compound: Compound (I) is chosen from 28 compounds e.g. 9-(4'-carbazol-9-yl-biphenyl-4-yl)-2-(1-phenyl-1H-benzoimidazol-2-yl)-9H-carbazole, 9-(3,5-bis-carbazol-9-yl-phenyl)-2-(1-phenyl-1H-benzoimidazol-2-yl)-9H-carbazole, 9-(3',5'-bis-carbazol-9-yl-biphenyl-4-yl)-2-(1-phenyl-1H-benzoimidazol-2-yl)-9H-carbazole, 2-(1-phenyl-1H-1,3-benzodiazol-2-yl)-9-(4-(4-(2-(1-phenyl-1H-1,3-benzodiazol-2-yl)-9H-carbazol-9-yl)phenyl)phenyl)-9H-carbazole, and 9-(3',5'-bis-carbazol-9-yl-biphenyl-3-yl)-2-(1-phenyl-1H-benzoimidazol-2-yl)-9H-carbazole. Preferred Properties: Compound (I) has a glass transition temperature of 110 degrees C or more and a thermal decomposition temperature of 400 degrees C or more. Preferred Definitions:    L=group of formula (i or ii);    R5=H or 1-10C lower alkyl;    h=1-4;and    R1,R2=phenyl.    EXAMPLE - (In g) 9-(4-bromo-phenyl)-2-(1-phenyl-1H-benzoimidazol-2-yl)-9H-carbazole (5), 4-(N-carbazolyl)-phenyl boronic acid pinacolate (3.58), and tetrakis(triphenylphosphine)palladium (0) (0.49) were suspended in a mixture of toluene (100 ml) and tetrahydrofuran (100 ml). The suspension, potassium carbonate (1.96), and water (100 ml) were mixed and heated for 9 hours under nitrogen atmosphere. The reaction mixture was layer-separated. The organic layer was washed with sodium chloride saturated aqueous solution, and dried. After solvent distillation, the residue was dissolved in toluene, filtered, and washed with toluene to obtain 9-(4'-carbazol-9-yl-biphenyl-4-yl)-2-(1-phenyl-1H-benzoimidazol-2-yl)-9H-carbazole (4) with a yield of 60%. The compound provided a display device having a drive voltage of 5.3 V, a brightness of 52.09 cd/A, and a luminous efficiency of 34.32 lm/W.