Operationally Stable and Efficient CsPbI<sub>3–<i>x</i></sub>Br<sub><i>x</i></sub> Perovskite Nanocrystal Light-Emitting Diodes Enabled by Ammonium Ligand Surface Treatment
Yiyue Zhang, Lata Chouhan, Eduard Fron, Luca Leoncino, Karim Elkhouly, Harshita Bhatia, Weiming Qiu, Maarten B. J. Roeffaers, Johan Hofkens, Elke Debroye, Bapi Pradhan
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 CsPbI 3– x Br x 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 ( T 50 ) of 50 min, which is seven times higher than the untreated device ( T 50 = 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.