Ultra-high power efficiency organic light-emitting diodes based on hot-exciton-assisted exciplex (HEAE) system

Power efficiency (PE) is crucial for evaluating organic light-emitting diode (OLED) performance, as it directly reflects photoelectric conversion efficiency. Exciplexes, featuring low injection barriers, offer greater potential than single compounds for high PE, but slow exciton dynamics hinder their development. Here, we introduce a novel strategy of hot-exciton-assisted exciplex (HEAE), which enhances the electroluminescence performance of exciplex systems from aspects of exciton and carrier dynamics. The feature of recovered exciton energy and accelerated reverse intersystem crossing process driven by the hot-exciton material improved the exciton utilization within the exciplex. As a result, the concepted exciplex showsa twice external quantum efficiency (EQE) of 19.0% than exciplex systems composed of conventional materials. Meanwhile, the moderate electron mobilityof hot-exciton material facilitates carrier transportbetween donors, enabling barrier-free injection in concepted exciplex-based OLEDs, which achieve a maximum PE up to82.1 lm W⁻¹. To further prove the superiority of the HEAE system, the exciplex-sensitized fluorescence OLEDs with narrow emission are designed, affording high EQEs of up to 40.5% and setting a new record for breakthrough PE exceeding 230 lm W⁻¹.