Rational arrangement of multiple exciplex hosts for highly efficient white organic light-emitting diodes

Abstract

Energy matching between the triplet level of the exciplex hosts and phosphorescent emitters is of particular importance to achieve highly efficient exciplex-based white organic light emitting diodes (WOLEDs). Herein, we design a novel exciplex host and use it for WOLEDs by arranging rational multiple-exciplex hosts in emissive layers. The resulting two-color warm WOLED, by doping blue and orange phosphorescent emitters, shows a maximum forward-viewing power efficiency and external quantum efficiency (EQE) of 104.6 lm W⁻¹ and 30.9%, respectively. Significantly, the EQE still remains 22.1% at 5000 cd m⁻². Meanwhile, the three-color warm WOLED has a high color rendering index of over 80 with a maximum EQE of 27.0% and the EQE can remain 21.3% at 5000 cd m⁻². These results indicate that rational arrangement of multiple-exciplex hosts in emissive layers is promising for the fabrication of highly efficient WOLEDs.