Controlling Ion Distribution for High-Performance Organic Light-Emitting Diodes Based on Sublimable Cationic Iridium(III) Complexes.

Sublimable charged iridium(III) complexes are becoming an attractive family of new phosphors and making their way into vacuum-evaporated-deposited organic light-emitting diodes, while it remains challenging to achieve high device performance. Here, we demonstrate a substantial mitigation of exciton quenching not only by reducing the dopant concentration, but also by controlling the ion distribution in the emissive material layers. We, therefore, achieved green luminescence with high brightness, superior efficiencies, and low driving voltages. Following this strategy, we further developed another six sublimable charged iridium(III) complexes and attained blue-green, yellow, and red-emitting devices with record-high performance. This study represents an important advance in the construction of bright electroluminescence from ionic transition metal complexes and shows their great promise in various optoelectronic applications.