TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation: No general preparation given. Preferred Composition: The nitrogen-containing partial structure (I) of polycyclic aromatic compound is chosen from 53 nitrogen-containing partial structures e.g. nitrogen-containing partial structures of formula (II)-(VI). The polycyclic aromatic compound is of formula (II-1). The polycyclic aromatic compound (II-1) is chosen from 46 polycyclic aromatic compounds e.g. polycyclic aromatic compound of formula (VII)-(XI).Z=Se, S, O or N;Y'=CR or N;or adjacent two Y'+O, S or Se=NR;R=H, halo, hydroxy-1-20C alkyl, trifluoromethyl, 2-12C perfluoroalkyl, 3-8C cycloalkyl, mono- or di-aryl substituted alkenyl, 1-20C alkyl, 2-20C alkenyl, 2-20C alkynyl, mono- or di-heteroaryl substituted alkenyl, aryl ethynyl, heteroaryl ethynyl, hydroxy, 1-20C alkoxy, aryloxy, trifluoromethoxy, trifluoroethoxy, 2-12C perfluoroalkoxy, 1-20C alkyl carbonyl, 1-20C alkylsulfonyl, cyano, nitro, amino, monoalkylamino, monoallylamino, monoheteroaryl amino, carbazole, 1-20C alkoxy carbonylamino, carbamoyl, mono- or di-alkyl carbamoyl, sulfamoyl, mono- or di-alkyl sulfamoyl, 1-20C alkylsulfonyl amino, 1-20C alkyl carbonyl amino, aryl, heteroaryl, 1-20C alkoxycarbonyl, carboxy, 5-tetrazolyl, sulfo, fluorosulfonyl, SRa, N(Ra)2, B(Ra)2, Si(Ra)3 or -CC-Si(Ra)3, in which alkyl, alkenyl, alkynyl or alkoxy is optionally substituted by 1-3 substituents chosen from halo, hydroxy, 1-20C alkoxy, aryloxy, amino, carbazole, N(Ra)2, trifluoromethyl, 2-12C perfluoroalkyl, 3-8C cycloalkyl, aryl and heteroaryl, aryl, carbazole or heteroaryl is optionally substituted by halo, 1-20C alkyl, hydroxy-1-20C alkyl, trifluoromethyl, 2-12C perfluoroalkyl, 3-8C cycloalkyl, 2-20C alkenyl, 2-20C alkynyl, mono- or di-aryl substituted alkenyl, mono- or di-heteroaryl substituted alkenyl, aryl ethynyl, heteroaryl ethynyl, hydroxy, 1-20C alkoxy, aryloxy, trifluoromethoxy, trifluoroethoxy, 2-12C perfluoroalkoxy, cyano, nitro, amino, carbazole, monoalkylamino, monoallylamino, monoheteroaryl amino or N(Ra)2, and carbamoyl, mono- or di-alkyl carbamoyl or sulfamoyl is optionally substituted by 1-5 substituents chosen from mono- or di-alkyl sulfamoyl, 1-20C alkyl carbonyl, 1-20C alkylsulfonyl, 1-20C alkylsulfonyl amino, 1-20C alkyl carbonylamino, methylenedioxy, heteroaryl, aryl, halo, 1-20C alkyl, 3-8C cycloalkyl, 2-20C alkenyl, 2-20C alkynyl, hydroxy, trifluoromethyl, 2-12C perfluoroalkyl, hydroxy, 1-20C alkoxy, aryloxy, trifluoromethoxy, trifluoroethoxy, 2-12C perfluoroalkoxy, 1-20C alkyl carbonyl, 1-20C alkylsulfonyl, methylenedioxy, cyano, nitro, amino, carbazole and N(Ra)2;or adjacent two R+C=monocyclic group, bicyclic group or tricyclic group of 5-membered ring or 6-membered ring optionally having hetero atom;or three adjacent R+C=bicyclic group or tricyclic optionally having hetero;Ra=alkyl, aryl or heteroaryl (all optionally substituted);andor two Ra=bicyclic group or tricyclic group optionally having hetero atom.When two adjacent R groups adjoin, R is single bond, CH2, CHRa, CRa2, NRa, Si(Ra)2, BRa, Se, S or O. SPECIFIC COMPOUNDS - 28 Polycyclic aromatic compounds are disclosed e.g. 4b-aza-12b-thiophosphadibenzo(g,p)chrysene of formula (Ia), 4b-aza-12b-phenyl-12b-sila-dibenzo(g,p)chrysene, 4b-aza-12b-germanium-12b-phenyl-dibenzo(g,p)chrysene, 4b-aza-12b-bora-dibenzo(g,p)chrysene and 2,7-dibromo-4b-aza-12b-bora-dibenzo(g,p)chrysene.    EXAMPLE - Bis(biphenyl-2-yl)amine (in g) (3.21), tetrahydrofuran (50 mL), and hexane solution (6.13 mL) of butyllithium were mixed at -78 degrees C under argon atmosphere. Phosphorus trichloride (1.37) was added and stirred for 1 hour. The reaction mixture was heated and distilled. 1,2-Dichlorobenzene (80 mL), aluminum trichloride (4) and sulfur (0.481) were added and stirred at 120 degrees C for 18 hours. 1,4-Diazabicyclo (2.2.2)octane (3.36) was added and mixed. The resulting mixture was filtered and distilled, to obtain 4b-aza-12b-thiophosphadibenzo(g,p)chrysene (0.725), with yield of 19%.