Phosphorescent cationic iridium complexes have emerged as promising dopants for solution-processed OLEDs, but further enhancing their device performances to the level achieved by neutral iridium complexes has remained challenging. Herein, we report a series of cationic iridium complexes, namely [Ir(ppz)2(Mepyim)]PF6 (1), [Ir(Mephtz)2(Mepyim)]PF6 (2), [Ir(tPhTAZ)2(Mepyim)]PF6 (3) and [Ir(CF3-dPhTAZ)2(Mepyim)]PF6 (4) for highly-efficient solution-processed OLEDs, which use 1-phenyl-1H-pyrazole (ppz), 1,3-dimethyl-5-phenyl-1H-1,2,4-triazole (Mepht...
