TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (disclosed): The imidazole derivative is prepared by reacting substituted aniline compound with benzoyl chloride or substituted benzoyl chloride and forming intermediate amide, reacting intermediate amide with phosphorus pentachloride or phosphorus oxychloride and preparing imidoyl halide intermediate, reacting prepared intermediate with 2,2-dimethoxyethaneamine and obtaining phenylimidazole ligand, adding phenylimidazole ligand to iridium acetylacetonate, and reacting under pressure. Preferred Property: The deuteration rate of imidazole derivative is 10% or more. Preferred Components: The imidazole derivative is an electroactive compound. The photoactive layer further contains a host material. The host material contains an organic compound of formula: Ar1(Cz)n (II).Ar1=aryl or deuterated analog;Cz=N-carbazolyl, diphenyl-N-carbazolyl, or deuterated analog;andn=1-4. Preferred Definitions:    R3,R7=silyl or deuterated silyl;    R1,R2,R4-R6,R8-R11=H or D;and    Ar1=biphenyl, terphenyl, triphenylenyl, phenanthrenyl, fluorenyl, chrysenyl, dibenzothiophenyl, dibenzofuryl, pyridyl, pyridazinyl, pyrimidinyl, pyrazinyl, triazinyl, benzimidazolyl, benzothiazolyl, quinolinyl, isoquinolinyl, benzofuropyridinyl, furodipyridinyl, benzothieno pyridinyl, thienodipyridinyl, or deuterated analog.    SPECIFIC COMPOUNDS - 12 Imidazole derivatives e.g. tris(2-phenyl-1-(2-phenyl-6-(propan-2-yl)phenyl)-1H-imidazole)iridium of formula (II), tris(1-(2,4-diphenyl-6-(propan-2-yl)phenyl)-2-phenyl-1H-imidazole)iridium, tris(2-phenyl-1-(2-(propan-2-yl)-6-(trimethylsilyl)phenyl)-1H-imidazole)iridium, tris(2-phenyl-1-(2-phenyl-6-(propan-2-yl)phenyl)-1H-imidazole)iridium, and 1-(2-phenyl-6-(propan-2-yl)phenyl)-2-(3-(triphenylsilyl)phenyl)-1H-imidazole, are specifically claimed.    EXAMPLE - 6.25 g N-(2-phenyl-6-(propan-2-yl)phenyl)benzamide, 4.12 g phosphorus pentachloride, and 40 mL phosphorus oxychloride were mixed, to obtain a mixture. The mixture was refluxed for 3 hours under nitrogen, and the excessive phosphorus oxychloride was distilled off. 2,2-Dimethylethanolamine dissolved in 40 mL propanol was added to the residue, and the resultant mixture was stirred at room temperature for 4 hours. 40 mL Concentrated hydrochloric acid was slowly added to the mixture and the resultant mixture was refluxed. The cooled mixture was treated using sodium hydroxide, and the pH of mixture was adjusted to 10. The mixture was further treated using 200 mL ethyl acetate. The mixture was passed through a silica bed, and the filtrate was transferred to a funnel, to extract the organic layer. The separated organic layer was dried, concentrated, and purified by column chromatography, to obtain 2-phenyl-1-(2-phenyl-6-(propan-2-yl)phenyl)-1H-imidazole as a solid. 3.5 g 2-Phenyl-1-(2-phenyl-6-(propan-2-yl)phenyl)-1H-imidazole and 1.01 g iridium(III) acetylacetonate were added to a long-necked round bottom flask. The reaction mixture was purged with nitrogen, and heated at 242 degrees C for 72 hours. The reacted mixture was cooled to room temperature, and dissolved in ethyl acetate. The resultant mixture was purified by silica gel chromatography, to obtain tris(2-phenyl-1-(2-phenyl-6-(propan-2-yl)phenyl)-1H-imidazole)iridium, with yield of 83%.