Cationic Iridium(III) Complexes Bearing Different Bulky N,N′-Chelating Ligands

Six cationic iridium(III) complexes bearing different bulky N,N′-chelating ligands were successfully synthesized and characterized by spectroscopic, electrochemical, thermal and photophysical methods. Because the molecular quenching and self-aggregation within molecules would deteriorate the device efficiency, the bulky molecules can suppress these problems and improve the device performance. The best doped organic light-emitting diodes based on these charged Ir(III) complex E1 exhibited L max of 26,800 cd/m 2 , η L, max of 35.0 cd/A and η P, max of 18.5 lm/W, which also showed a small efficiency roll-off in the range of 100 to 1000 cd/m 2 .