All-fluorescence white organic light-emitting diodes with record-beating power efficiencies over 130 lm W‒1 and small roll-offs
Hao Liu, Yan Fu, Ben Zhong Tang, Zujin Zhao
Abstract
Abstract Improving power efficiency ( PE ) and reducing roll-off are of significant importance for the commercialization of white organic light-emitting diodes (WOLEDs) in consideration of energy conservation. Herein, record-beating PE of 130.7 lm W −1 and outstanding external quantum efficiency ( EQE ) of 31.1% are achieved in all-fluorescence two-color WOLEDs based on a simple sandwich configuration of emitting layer consisting of sky-blue and orange delayed fluorescence materials. By introducing a red fluorescence dopant, all-fluorescence three-color WOLEDs with high color rendering index are constructed based on an interlayer sensitization configuration, furnishing ultrahigh PE of 110.7 lm W −1 and EQE of 30.8%. More importantly, both two-color and three-color WOLEDs maintain excellent PE s at operating luminance with smaller roll-offs than the reported state-of-the-art WOLEDs, and further device optimization realizes outstanding comprehensive performances of low driving voltages, large luminance, high PE s and long operational lifetimes. The underlying mechanisms of the impressive device performances are elucidated by host-tuning effect and electron-trapping effect, providing useful guidance for the development of energy-conserving all-fluorescence WOLEDs.