TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Components: The organic thin layer is: an emission layer (130), which comprises a phosphorescent or fluorescent host comprising (I), and a phosphorescent or fluorescent dopant comprising red, green, blue or white emitting dopants; and a hole transport layer (140), a hole injection layer (170), an electron transport layer and/or an electron injection layer.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: (I) has the structure of formula (Iaa).X, Y1=N (preferred), S or O;Ar1, Ar2=6-30C aryl or arylene, 1-30C alkyl or alkylene, or 2-30C heteroaryl or heteroarylene (all optionally substituted with halo, 1-30C (halo)alkyl, 6-30C aryl, 2-30C heteroaryl and/or 1-20C alkoxy), preferably phenyl; eitherR5-R8=6-30C aryl or arylene, 1-30C alkyl or alkylene, or 2-30C heteroaryl or heteroarylene (all optionally substituted with one substituent comprising halo, 1-30C (halo)alkyl, 6-30C aryl, 2-30C heteroaryl and/or 1-20C alkoxy) or H, preferably phenyl, naphthyl, anthryl, phenanthryl, naphthacenyl, pyrenyl, biphenylyl, terphenylyl, tolyl, pyrrol, pyrazinyl, pyrimidyl, pyridazinyl, pyridinyl, indolyl, puryl, benzofuranyl, quinolyl, quinoxalinyl, phenanthridinyl, acridinyl, phenanthrolinyl, phenazinyl, phenothiazinyl, phenoxazinyl, oxazolyl, oxadiazolyl or thienyl; orR5R6, R7R8=cycle, preferably fused heteroaryl group of formula (a);m, n=0-3, where m+n is 1-6;X1-X8=CR1a or N;R1a=R1; ando, p=0-2.Provided that: when X is S or O, at least one of R5 or R6 is a lone pair electron, and when Y1 is S or O, at least one of R7 or R 8 is a lone pair electron. SPECIFIC COMPOUNDS - The use of 53 compounds (I) is specifically claimed e.g. 5-(5-(10-(1-naphthyl)-9-anthryl)-3-pyridyl)-N1,N1,N3,N3-tetraphenyl-benzene-1,3-diamine of formula (Ia), 5-(5-(3,5-bis(bis(2-naphthyl)amino)phenyl)-3-pyridyl)-N1,N1,N3,N3-tetrakis(2-naphthyl)benzene-1,3-diamine, 5-(5-(3-((2E,3Z)-2-allylidene-3-ethylidene-indolin-1-yl)-5-carbazol-9-yl-phenyl)-3-pyridyl)-N1,N1,N3,N3-tetrakis (2-naphthyl) benzene-1,3-diamine, 5-(5-(3,5-bis(bis(2-naphthyl)amino)phenyl)-3-pyridyl)-N1,N1,N3,N3-tetrakis(p-tolyl)benzene-1,3-diamine and 5-(5-(3-(bis(2-naphthyl)amino)-5-carbazol-9-yl-phenyl)-3-pyridyl)-N1,N3,N3-tris(2-naphthyl)-N1-(3-((Z)-prop-1-enyl)-4-vinyl-phenyl)benzene-1,3-diamine.    EXAMPLE - 9-(3-(4,4,5,5-Tetramethyl-(1,3,2)dioxaborolane)-5-carbazol-9-yl-phenyl)carbazole (45.1 g), 3,5-dibromopyridine (20 g) and tetrakis-(triphenylphosphine)palladium (2.44g) were suspended in tetrahydrofuran (THF) (600 ml) and toluene (400 ml), and then a solution of potassium carbonate (23.3 g) dissolved in water (400 ml) was added. The mixture was refluxed for 12 hours while heating and worked up to give 9-(3-(5-bromo-3-pyridyl)-5-carbazol-9-yl-phenyl)carbazole (a1). 9-Bromo-10-naphthalen-1-yl-anthracene (5 g) was dissolved in THF (350 ml), and then n-butyl lithium hexane solution (1.6M, 8.12 g) was added under an argon atmosphere at -70 degrees C. The solution was agitated at -70 to 40 degrees C for 1 hour. The agitated reaction solution was frozen to -70 degrees C, and isopropyltetramethyl dioxaborolane (2.41 g) was slowly added in a dropwise fashion and worked up to give 4,4,5,5-tetramethyl-2-(10-naphthalen-1-yl-anthracen-9-yl)-(1,3,2)dioxaborolane (a2). (a1) (3 g), (a2) (2.28 g), and tetrakis-(triphenylphosphine)palladium (0.3 g) were suspended in THF (100 ml) and toluene (100 ml), and then a solution of potassium carbonate (0.73 g) dissolved in water (100 ml) was added. The mixture was refluxed for 9 hours while heating and worked up to give 5-(5-(10-(1-naphthyl)-9-anthryl)-3-pyridyl)-N1,N1,N3,N3-tetraphenyl-benzene-1,3-diamine (2.21 g).