Operationally Stable and Efficient CsPbI_3-x Br _x Perovskite Nanocrystal Light-Emitting Diodes Enabled by Ammonium Ligand Surface Treatment

Nanocrystals(NCs) of inorganic lead halide perovskites with narrowemission line widths hold great potential for next-generation color-saturatedoptoelectronic devices. However, their stability and electroluminescenceperformance are currently hindered by environment-dependent structuredeterioration over time and inferior carrier transport. These limitationsare closely related to the surface defect-mediated nonradiative energylosses of the NCs. Herein, we have developed a comprehensive surfaceoptimization strategy for CsPbI3-x Br x NCs, involving molecular passivation,phase stability optimization, and effective electron transport forconstructing a durable device. This results in a high-efficiency perovskitelight-emitting diode (PeLED) exhibiting red emission with a maximumat 685 nm and an external quantum efficiency of up to 12.35%. Furthermore,the optimized device shows a much improved operational stability witha half-lifetime (T (50)) of 50 min, whichis seven times higher than the untreated device (T (50) = 7 min). Additionally, the passivated NCs exhibitnon-blinking characteristics at the single-particle level. This workhighlights the immense potential of amino-rich ligands in stabilizingperovskite NCs for efficient and operationally stable LEDs.