Post-synthesis Treatment with Lead Bromide for Obtaining Near-Unity Photoluminescence Quantum Yield and Ultra-stable Amine-Free CsPbBr3 Perovskite Nanocrystals

Improving the photoluminescence quantum yields (PLQYs) and optimizing the stability have been challenging tasks to promote cesium lead halide (CsPbX3; X = Cl, Br, and I) perovskite nanocrystals (PNCs) for real optoelectronic applications. In recent years, the amine-free synthesis route has become an option for making stable CsPbX3 PNCs. Further improvement in the PLQY and stability of amine-free PNCs is paramount for their practical applications. Herein, we have introduced a simple lead bromide (PbBr2) post-treatment process to achieve the near-unity PLQY (>95%) in amine-free CsPbBr3 PNCs. Furthermore, PbBr2 treatment enables these materials to have a drastically improved stability under different environmental conditions (polar solvents, light, and heat). In addition, a green-emitting down-converted light-emitting diode was fabricated using PbBr2-treated amine-free CsPbBr3 PNCs, which shows its considerable prospects for display applications. Thus, our results will promote these PbBr2-treated amine-free inorganic perovskite nanocrystals for commercial development in optoelectronic applications.