TECHNOLOGY FOCUS - ELECTRONICS - Preferred Components: The first organic layer is an emissive layer and (I) are a host in the first organic layer. The emissive layer further comprises a phosphorescent emitter. The phosphorescent emitter is an iridium complex of formula (II). The phosphorescent emitter is a compound comprising a phosphorescent metal complex comprising a monoanionic, bidentate ligand, which is a substituted aryl group of formula (III), where the metal is non-radioactive metals with atomic numbers of greater than 40; and the bidentate ligand may be linked with other ligands to comprise a tridentate, tetradentate, pentadentate or hexadentate ligand. The device further comprises a second organic layer that is a non-emissive layer. The first organic layer is adjacent to the second organic layer. The phosphorescent emitter has a triplet energy of 425-495 (preferably 440-480) nm, when X in (I) is dibenzothiophene, dibenzofuran, benzofuropyridine, furodipyridine, benzothienopyridine, thienodipyridine or triphenylene, and R in (I) is hydrogen, alkyl, benzene, biphenyl, terphenyl, dibenzothiophene or dibenzofuran. The phosphorescent emitter has a triplet energy of 495-570 (preferably 510-530) nm, when X in (I) is biphenyl, terphenyl, triphenylene, phenanthrene, fluorene, dibenzothiophene, dibenzofuran, pyridine, pyridazine, pyrimidine, pyrazine, triazine, benzimidazole, benzothiazole, quinoline, isoquinoline, benzofuropyridine, furodipyridine, benzothienopyridine or thienodipyridine, and R in (I) is hydrogen, alkyl, benzene, biphenyl, terphenyl, triphenylene, phenanthrene, fluorene, dibenzothiophene, dibenzofuran, pyridine, pyridazine, pyrimidine, pyrazine, triazine, benzimidazole, benzothiazole, quinoline, isoquinoline, benzofuropyridine, furodipyridine, benzothienopyridine or thienodipyridine.n = 1-3; eitherR1a, R1b, R1c, R1d, R1e, R1f, R1g, R1h, R1i = H, hydrocarbyl (optionally heteroatom substituted), CN, F, OR2a, SR2a, NR2aR2b, BR2aR2b or SiR2aR2bR2c; orany two of R1a, R1b, R1c, R1d, R1e, R1f, R1g, R1h, R1i = optionally saturated, aromatic or non-aromatic ring; eitherR2a, R2b, R2c = hydrocarbyl (optionally heteroatom substituted); orany two of R2a, R2b, R2c = optionally saturated, aromatic or non-aromatic ring;X-Y1 = an ancillary ligand; andE1a, E1b, E1c, E1d, E1e, E1f, E1g, E1h, E1i, E1j, E1k, E1l, E1m, E1n, E1o, E1p, E1q = C or N and collectively comprise an 18 pi-electron system.Provided that: R1a, R1b, R1c, R1d, R1e, R1f, R1g, R1h, R1i is other than H when attached to N; and E1a, E1p are different.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation: No preparation method is given. Preferred Definitions:    a = 1 (preferred) or 2;    b = 1;    n = 0 or 1;    X = dibenzothiophene, dibenzofuran, benzofuropyridine, furodipyridine, benzothienopyridine, thienodipyridine or triphenylene; and    R = H, alkyl, benzene, biphenyl, terphenyl, dibenzothiophene or dibenzofuran.    SPECIFIC COMPOUNDS - 158 Compounds (I) are specifically claimed e.g. 9-pyridin-2-yl-9H-(3,9')bicarbazolyl of formula (Ia), 9-dibenzothiophen-4-yl-9H-(3,9')bicarbazolyl, 9-dibenzothiophen-1-yl-9H-(3,9')bicarbazolyl, 9-dibenzofuran-1-yl-9H-(3,9')bicarbazolyl, and 9-benzo(4,5)furo(2,3-b)pyridin-5-yl-9H-(3,9')bicarbazolyl.    EXAMPLE - 3-(9-Carbazolyl)-9-tosylcarbazole (10 g), sodium hydroxide (8 g), tetrahydrofuran (80 ml), methanol (40 ml) and water (40 ml) were added to a flask. The reaction mixture was heated to reflux for 12 hours. After cooling, the mixture was purified to give 3-(9-carbazolyl)carbazole (Q). (Q) (3 g), 2-bromopyridine (1.9 g), copper iodide (0.2 g), trans-1,2-diaminocyclohexane (0.2 g), potassium phosphate tribasic (5.3 g), and toluene (150 ml) were added to a flask. The reaction mixture was heated to reflux and stirred under a nitrogen atmosphere for 24 hours. After cooling, the mixture was purified to give 9-pyridin-2-yl-9H-(3,9')bicarbazolyl (2.2 g).