Operationally Stable and Efficient CsPbI_3–<i>x</i>Br_<i>x</i> Perovskite Nanocrystal Light-Emitting Diodes Enabled by Ammonium Ligand Surface Treatment

Abstract

Nanocrystals (NCs) of inorganic lead halide perovskites with narrow emission line widths hold great potential for next-generation color-saturated optoelectronic devices. However, their stability and electroluminescence performance are currently hindered by environment-dependent structure deterioration over time and inferior carrier transport. These limitations are closely related to the surface defect-mediated nonradiative energy losses of the NCs. Herein, we have developed a comprehensive surface optimization strategy for CsPbI3–xBrx NCs, involving molecular passivation, phase stability optimization, and effective electron transport for constructing a durable device. This results in a high-efficiency perovskite light-emitting diode (PeLED) exhibiting red emission with a maximum at 685 nm and an external quantum efficiency of up to 12.35%. Furthermore, the optimized device shows a much improved operational stability with a half-lifetime (T50) of 50 min, which is seven times higher than the untreated device (T50 = 7 min). Additionally, the passivated NCs exhibit non-blinking characteristics at the single-particle level. This work highlights the immense potential of amino-rich ligands in stabilizing perovskite NCs for efficient and operationally stable LEDs.