We demonstrate that three Ir (III) complexes used as principal dopants in organic electrophosphorescent diodes have very high photoluminescence quantum efficiency (ηPL) in a solid-state film. The green emitting complex, fac-tris(2-phenylpyridinato)iridium(III) [Ir (ppy)3], the red-emitting bis [2- (2′ -benzothienyl) pyridinato-N, C3′] (acetylacetonato)iridium(III) [Btp2 Ir(acac)], and the blue complex bis [(4,6-difluorophenyl) pyridinato-N, C2] (picolinato) iridium(III) (FIrpic) were prepared as codeposited films of varying concentration with 4, 4′ -bis (N-carbazolyl) -2, 2′ -biphenyl, a commonly used host material. The maximum ηPL values for Ir (ppy)3, Btp2 Ir(acac), and FIrpic were, respectively, 97%±2% (at 1.5 mol%), 51%±1% (at 1.4 mol%), and 78%±1% (at 15 mol%). Furthermore, we also observed that the maximum ηPL of FIrpic reached 99%±1% when doped into the high triplet energy host, m-bis (N-carbazolyl) benzene, at an optimal concentration of 1.2 mol%.
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