Bis-tridentate Ir(III) emitters with complementary carbene cyclometalates targeted for efficient blue phosphorescence and hyperluminescence

Abstract

Blue phosphors present a significant challenge in the development of organic light-emitting diodes (OLEDs). In this contribution, we designed a new class of bis-tridentate Ir(III) phosphors featuring two complementary carbene cyclometalates. They possessed efficient blue emission with short radiative lifetimes in both the solution and thin film states, which enhances the full utilization of electrically generated triplet excitons. Particularly, one PhOLED device had given an external quantum efficiency (EQE) of 16.2% at 10000 cd m −2 , showing only a ∼4% roll-off from its maximum EQE of 16.9% at 2155 cd m −2 . Moreover, a related hyper-OLED device achieved true-blue emission with chromaticity coordinates (CIE x,y ) of (0.128, 0.107) and demonstrated a max. EQE of 32.7% and outstanding EQEs of 29.3% and 21.8% at a luminance of 1000 and 10000 cd m −2 , respectively. These results represent a significant advancement in the development of both blue phosphorescence and hyperphosphorescence with potential for practical applications.