Ir(III) Metal Emitters with Cyano‐Modified Imidazo[4,5‐b]pyridin‐2‐ylidene Chelates for Deep‐Blue Organic Light‐Emitting Diodes
Yixin Wu, Yangyang Xin, Yi Pan, Shek‐Man Yiu, Jie Yan, Kai‐Chung Lau, Lian Duan, Yün Chi
Abstract
Abstract Ir(III) carbene complexes have been explored as one of the best blue phosphors for their high performance. Herein, the authors designed and synthesized a series of blue‐emitting Ir(III) phosphors ( f ‐ct9a–c), featuring fac ‐coordinated cyano‐imidazo[4,5‐b]pyridin‐2‐ylidene cyclometalates. These Ir(III) complexes exhibit true‐blue emission with a peak maximum spanning 448–467 nm, with high photoluminescence quantum yields of 81–88% recorded in degassed toluene. Moreover, OLED devices bearing phosphors f ‐ct9a and f ‐ct9b deliver maximum external quantum efficiencies (EQE max ) of 25.9% and 30.3%, together with Commission Internationale de L'Eclairage (CIE x,y ) coordinates of (0.157, 0.225) and (0.142, 0.169), respectively. Remarkably, the f ‐ct9b‐based device displays an incredible EQE of 29.0% at 5000 cd·m −2 . The hyper‐OLED device based on f ‐ct9b and ν‐DABNA exhibits an EQE max of 34.7% and CIE x,y coordinates of (0.122, 0.131), affirming high potentials in achieving efficient blue electroluminescence.