Sodium doping for enhanced performance by highly efficient CsPbBr3 quantum dot-based electroluminescent light-emitting diodes

Abstract

Metal halide perovskite quantum dots (QDs) are emerging as promising materials for illumination and display applications owing to their unique optical and electronic properties. However, research into the doping of perovskite QDs with alkali metal cations for use in light-emitting diode (LED) devices is limited. Herein, a facile and convenient room-temperature method for synthesizing Na⁺-ion-doped CsPbBr₃ QDs is presented. Through the optimization of the Na⁺ doping concentration, the as-prepared Na⁺-doped CsPbBr₃ QDs display a higher photoluminescence quantum yield of 94.74%, faster radiative recombination rate of 30.4 μs⁻¹, and longer lifetime of 31.2 ns than their undoped counterparts, allowing the practical realization of high-efficiency electroluminescent QD LED (QLED) devices. As a result, a maximum luminance of 20 190 cd m⁻², a peak current efficiency of 34.5 cd A⁻¹, and an external quantum efficiency of 8.97% for as-fabricated QLEDs are obtained; all these characteristics are higher than those of the control device with undoped CsPbBr₃ QDs. Experimental studies combined with auxiliary theoretical calculations indicate that the enhanced performance can be chiefly attributed to the decreased trap defect density of the perovskite upon sodium incorporation. This research indicates the immense potential of the Na⁺-doped CsPbBr₃ QDs to act as an emission layer for use in the next-generation illumination and display fields.