Ultra-High Power Efficiency Organic Light-Emitting Diodes Based on Hot-Exciton-Assisted Exciplex (HEAE) System

Abstract

Power efficiency (PE) is crucial for evaluating organic light-emitting diode (OLED) performance, as it directly reflects photoelectric conversion efficiency. Featuring a low injection barrier, exciplex shows greater potential than a single compound in fabricating high-PE OLEDs, but poor efficiencies hinder their development. Here, we introduce a novel strategy of hot-exciton-assisted exciplex (HEAE), where hot-exciton materials enhance the efficiencies of exciplex systems as donors via recovering exciton energy. As a result, the novel exciplex system shows an external quantum efficiency (EQE) of 19.0%, which is twice of the EQE of conventional exciplex. Moreover, using the novel exciplex as the host of four multiple resonance emitters, the sensitized fluorescence OLEDs with narrow emission achieve high EQEs of up to 40.5% and a new record for breakthrough PE exceeding 230 lm W⁻¹. These results proved that hot-exciton material is an excellent candidate for high-performance exciplexes, providing valuable insights into the rational design for low-power-consumption OLEDs.