TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation: No general preparation given. Preferred Composition: The nitrogen-containing heteroaromatic ring compound (I) is of formula (II)-(VI). The light-emitting layer comprises phosphorescence-emitting material. The phosphorescence-emitting material is o-metalated complex of metal atom chosen from iridium, osmium and platinum. The organic electroluminescent element further has organic thin film layer provided between cathode and light-emitting layer. The organic thin film layer comprises electron-donating dopant and organometallic complex. SPECIFIC COMPOUNDS - 157 nitrogen-containing heteroaromatic ring compounds are disclosed. e.g. 3-(12-(9H-carbazol-9-yl)-8-oxatricyclo(7.4.0.02,7)trideca-1(9),2(7),3,5,10,12-hexaen-4-yl)-9-(5-(9H-carbazol-9-yl)pyridin-3-yl)-9H-carbazole of formula (Ia), 12-(3-(12-(9H-carbazol-9-yl)-8-oxatricyclo(7.4.0.0 2,7)trideca-1(9),2(7),3,5,10,12-hexaen-4-yl)-9H-carbazol-9-yl)-8-oxa-3-azatricyclo(7.4.0.0 2,7)trideca-1(9),2(7),3,5,10,12-hexaene, 3-(12-(9H-carbazol-9-yl)-8-oxatricyclo(7.4.0.0 2,7)trideca-1(9),2(7),3,5,10,12-hexaen-4-yl)-9-(4-(9H-carbazol-9-yl)pyrimidin-2-yl)-9H-carbazole, 3-(12-(9H-carbazol-9-yl)-8-oxatricyclo(7.4.0.0 2,7)trideca-1(9),2(7),3,5,10,12-hexaen-4-yl)-9-(5-phenyl-5H-pyrido(3,2-b)indol-8-yl)-9H-carbazole, and 3-(12-(9H-carbazol-9-yl)-8-oxatricyclo(7.4.0.0 2,7)trideca-1(9),2(7),3,5,10,12-hexaen-4-yl)-9-(5-(5-(9H-carbazol-9-yl)pyridin-3-yl)pyridin-3-yl)-9H-carbazole.    EXAMPLE - 9-(12-methyl-8-oxatricyclo(7.4.0.0 2,7)trideca-1(9),2,4,6,10,12-hexaen-4-yl)-9H-carbazole intermediate was reacted with 3-bromo-9H-carbazole, aqueous sodium carbonate solution and tetrakis(triphenylphosphine)palladium were added, and refluxed for 8 hours. Organic phase was extracted with dichloromethane and concentrated under reduced pressure to obtain 9-(12-(9H-carbazol-3-yl)-8-oxatricyclo(7.4.0.0 2,7)trideca-1(9),2,4,6,10,12-hexaen-4-yl)-9H-carbazole. 9H-Carbazole was reacted with dibromopyridine and trans-1,2-diaminocyclohexane and potassium phosphate in presence of copper iodide to obtain 9-(5-bromopyridin-3-yl)-9H-carbazole. 9-(12-(9H-carbazol-3-yl)-8-oxatricyclo(7.4.0.0 2,7)trideca-1(9),2,4,6,10,12-hexaen-4-yl)-9H-carbazole and 9-(5-bromopyridin-3-yl)-9H-carbazole were reacted in tris (dibenzylidene acetone)dipalladium and t-butylphosphonium tetrafluoroborate in presence of xylene to obtain 3-(12-(9H-carbazol-9-yl)-8-oxatricyclo(7.4.0.0 2,7)trideca-1(13),2(7),3,5,9,11-hexaen-4-yl)-9-(5-(9H-carbazol-9-yl)pyridin-3-yl)-9H-carbazole.