Surface-Passivated Pb-free Double-Perovskite Halide Quantum Dots for Electrically Driven Efficient White Light-Emitting Diodes

Abstract

Selected double-perovskite halides have demonstrated broad wavelength emission owing to the effectiveness of self-trapped excitons. Herein, specific double-perovskite halide quantum dots (QDs) composed of Cs2AgIn0.9Bi0.1Cl6 are proposed as the active layer in a rare example of electrically driven white light-emitting diodes (LEDs). The QDs are modified by substituting Na at the Ag site and post-treating the surface of QDs to control carrier transport for efficient emission. Compared with QDs without Na, an optimal QD composition of Cs2Ag0.6Na0.4In0.9Bi0.1Cl6 exhibited a higher photoluminescence quantum yield of 19.31% and a longer lifetime of 1.4 mu s. Additional post-treatment with an inorganic salt, KCl, further improved the luminance performance, attaining a notable peak luminance of 80.3 cd m-2 at a low bias of 6 V and a device half-lifetime of 36.5 min. These achievements are assumed to be primarily due to the combined effects of favorable band alignment, effective recombination, and defect passivation.