Electroluminescence and hyperphosphorescence from stable blue Ir(III) carbene complexes with suppressed efficiency roll-off
Jie Yan, Dong‐Ying Zhou, Liang‐Sheng Liao, Martin Kuhn, Xiuwen Zhou, Shek‐Man Yiu, Yün Chi
Abstract
Abstract Efficient Förster energy transfer from a phosphorescent sensitizer to a thermally activated delayed fluorescent terminal emitter constitutes a potential solution for achieving superb blue emissive organic light-emitting diodes, which are urgently needed for high-performance displays. Herein, we report the design of four Ir(III) metal complexes, f-ct1a ‒ d, that exhibit efficient true-blue emissions and fast radiative decay lifetimes. More importantly, they also undergo facile isomerization in the presence of catalysts (sodium acetate and p -toluenesulfonic acid) at elevated temperature and, hence, allow for the mass production of either emitter without decomposition. In this work, the resulting hyper-OLED exhibits a true-blue color (Commission Internationale de I’Eclairage coordinate CIE y = 0.11), a full width at half maximum of 18 nm, a maximum external quantum efficiency of 35.5% and a high external quantum efficiency 20.3% at 5000 cd m ‒2 , paving the way for innovative blue OLED technology.