Record-High Efficiency Blue-Green Cationic Ir(III) Complexes for Light-Emitting Electrochemical Cells with EQE Approaching 40.

Light-emitting electrochemical cells (LECs) provide a cost-effective solution for lighting applications and are well-suited for large-area and industrial-scale manufacturing. However, enhancing the efficiency of LECs remains a significant challenge. To address this issue, this study presents a series of blue-green iridium complexes with promising phosphorescent emission properties. Among these, di[1-(2,4-difluorophenyl)-pyrazolyl]-5,5'-difluoro-2,2'-bipyridyl iridium(III) hexafluorophosphate stands out, demonstrating exceptional performance. Following optimizing the device with varying thicknesses, an EQE of 16.8% and a current efficiency of 47.2 cd A were attained. Further enhancements through the integration of a diffusive layer resulted in a 270% increase in efficiency, reaching an EQE of 39.3% and current efficiency of 109.6 cd A. This efficient technology demonstrates significant potential and lays the groundwork for future high-performance light-emitting devices.