TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation: No preparation method is given. Preferred Components: The organic thin layer comprises an emission layer (130), a hole transport layer, a hole injection layer, an electron injection layer and/or hole blocking layer. (I) is included in an electron transport layer, an electron injection layer or an emission layer. (I) is included in an emission layer as a phosphorescent or fluorescent host or a fluorescent blue dopant. Preferred Definitions:    Ar1,Ar2 = phenyl, naphthyl, anthracenyl, phenanthrenyl, pyrenyl, perylenyl, chrysenyl, its combination;    Ar3 = imidazole, thiazolyl, oxazolyl, oxadiazolyl, triazolyl, pyridinyl, pyridazine, quinolinyl, isoquinolinyl,, acridinyl, imidazopyridinyl, imidazopyrimidinyl, diphenyl amine, dinaphthyl amine, dibiphenyl amine, phenyl naphthyl amine, phenyl diphenyl amine, ditolyl amine, phenyl tolyl amine, carbazole, triphenyl amine, dipyridyl amine, or its combination; and    L = phenylene.    SPECIFIC COMPOUNDS - 57 Compounds (I) are specifically claimed, i.e. 4,6-diphenyl-2-(4-pyridin-2-yl-phenyl)-pyrimidine compound of formula (Ia), 4,6-di-naphthalen-1-yl-2-(4-pyridin-2-yl-phenyl)-pyrimidine, 4,6-di-naphthalen-2-yl-2-(4-pyridin-2-yl-phenyl)-pyrimidine, 4-naphthalen-1-yl-6-phenyl-2-(4-pyridin-2-yl-phenyl)-pyrimidine and 4,6-di-phenanthren-9-yl-2-(4-pyridin-2-yl-phenyl)-pyrimidine.    EXAMPLE - 2,4,6-trichloropyrimidine (20 g), 2-naphthylboronic (37.5 g), and tetrakis-(triphenylphosphine)palladium (6.3 g) were suspended in a mixed solvent of tetrahydrofuran (600 ml) and toluene (400 ml) to provide a suspension. The suspension was added to a solution of potassium carbonate (60.3 g) was dissolved in water (400 ml), and the obtained mixture was heated and refluxed for 9 hours. After separating the reaction fluid into two layers, an organic layer was washed with a saturated sodium chloride aqueous solution and dried with anhydrous sodium sulfate. The organic solvent was distillated and removed under reduced pressure, and then the residue was recrystallized with toluene. The obtained crystal was separated by filtration and washed with toluene to obtain 2-chloro-4,6-di-naphthalen-2-yl-pyrimidine (A). Then, (A) (5 g), 2-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)pyridine (4.2 g) and tetrakis-(triphenylphosphine)palladium (0.39 g) were suspended in a mixed solvent of 150 ml of tetrahydrofuran and toluene (100 ml) to provide a suspension. The suspension was added to a solution of potassium carbonate (3.8 g) was dissolved in water (100 ml). The obtained mixture was heated and refluxed for 12 hours. After separating the reaction fluid into two layers, an organic layer was washed with a saturated sodium chloride aqueous solution and dried with anhydrous sodium sulfate. The organic solvent was distillated and removed under reduced pressure, and the residue was recrystallized with toluene. The obtained crystal was separated by filtration and washed with toluene to obtain 4,6-diphenyl-2-(4-pyridin-2-yl-phenyl)-pyrimidine (yield: 80.5 %).