Suppressing Nonradiative Recombination in Pure Red Perovskites Toward Efficient Hybrid Perovskite/Organic Tandem White Light-Emitting Diodes

Abstract

Perovskite light-emitting diodes (PeLEDs) have recently attracted great interest for their superior electroluminescent properties. However, the development of pure red (620–660 nm) PeLEDs as an essential component for display applications continues to be hampered by severe nonradiative recombination. Particularly, the solution fabrication process of perovskites poses a challenge in the fabrication of white PeLEDs, which further hinders their commercialization. Herein, a novel design is reported of high-efficiency hybrid perovskite/organic tandem white light-emitting diodes (POTWLEDs) by integrating bottom pure red (640 nm) PeLED units with top blue OLED units. To optimize device performance, 5-Bromo-2-fluoropyridine (PD) is introduced, featuring strong electronegative groups of C─N and C─F, as a pyridine passivator into pure red PeLEDs to inhibit nonradiative recombination in the perovskites by passivating defects and improving phase purity of perovskite films, which promotes a maximum external quantum efficiency (EQE) of 20.4%. By integrating the optimized red PeLED units with blue OLED units, efficient POTWLEDs are obtained with high EQE values of 25.9 and 23.7% with CIE coordinates of (0.279 and 0.339) and (0.310 and 0.330), respectively. These values represent the highest efficiencies reported for perovskite-based white light-emitting diodes (WLEDs), illustrating the great potential for solid-state lighting and display applications.