TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The electronic device comprises an anode, a cathode and at least one emitting layer, where at least one layer of the device includes emitting layers, electron transport layers, electron injection layers, and hole blocking layers.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (Claimed): Preparation of (I) comprises reacting indolocarbazole compound with an aromatic or heteroaryl ring system, which contains an electron-deficient heteroaryl group, where the aromatic or heteroaryl ring system is coupled to the nitrogen atom of the indolocarbazole. Preferred Components: (I) are present in the emitting layer in combination with one or more phosphorescent emitter compounds. SPECIFIC COMPOUNDS - 65 Compounds (I) are disclosed, e.g. 10-(4,6-diphenyl-(1,3,5)triazin-2-yl)-12,12-dimethyl-7-(9-phenyl-9H-carbazol-3-yl)-10,12-dihydro-10-aza-indeno(2,1-b)fluorene of formula (Ia), 10-(4,6-diphenyl-(1,3,5)triazin-2-yl)-12,12-diphenyl-7-(9-phenyl-9H-carbazol-3-yl)-10,12-dihydro-10-aza-indeno(2,1-b)fluorene, 7-(9-dibenzofuran-4-yl-9H-carbazol-3-yl)-10-(4,6-diphenyl-pyrimidin-2-yl)-12,12-dimethyl-10,12-dihydro-10-aza-indeno(2,1-b)fluorene, 7-(9-dibenzofuran-4-yl-9H-carbazol-3-yl)-10-(2,6-diphenyl-pyrimidin-4-yl)-12,12-dimethyl-10,12-dihydro-10-aza-indeno(2,1-b)fluorene, and 10-(2,6-di-naphthalen-1-yl-pyrimidin-4-yl)-12,12-dimethyl-7-(9-phenyl-9H-carbazol-3-yl)-10,12-dihydro-10-aza-indeno(2,1-b)fluorene.    EXAMPLE - 2 g of Magnesium was present in a 500 ml four-necked flask. A solution of 31.2 g of 5'-(3-bromphenyl)-(1,1';3',1'')terphenyl in 100 ml of tetrahydrofuran (THF) was added dropwise slowly to the four-necked flask. The reaction mixture was heated to boiling for 1.5 hours and then cooled at room temperature. In a second flask, 6.4 g of cyanogen chloride was introduced into 50 ml of THF and cooled to 0 degrees C. At the temperature, the cooled Grignard reagent was added dropwise to the reaction mixture for 12 hours at the room temperature. The reaction mixture was mixed with 150 ml of hydrochloric acid. The aqueous phase was extracted three times with dichloromethane. The combined organic phases were washed with water, dried over sodium sulfate and concentrated. The residue was recrystallized from toluene and further worked up to give 2-chloro-4,6-bis(3-(3,5-diphenylphenyl)phenyl)-1,3,5-triazine.