To overcome the roll-off efficiency of electrophosphorescent organic light-emitting devices, Ir (III) complexes of (ppz) 2Ir (NˆN) were synthesized and named for (ppz) 2Ir (tfmpptz),(ppz) 2Ir (fpptz),(ppz) 2Ir (tfmptz) and (ppz) 2Ir (pybi)(ppz: 1-phenylpyrazolato; NˆN: N, N′- heteroaromatic). Their molecular structures, photophysical properties and cyclic voltammetric data were reported. The crystals of (ppz) 2Ir (tfmpptz),(ppz) 2Ir (fpptz) are ...