Improving the Stability of Ball-Milled Lead Halide Perovskites via Ethanol/Water-Induced Phase Transition.

Recently, lead halide perovskite nanocrystals have been considered as potential light-emitting materials because of their narrow full width at half-maximum (FWHM) and high photoluminescence quantum yield (PLQY). In addition, they have various emission spectra because the bandgap can be easily tuned by changing the size of the nanocrystals and their chemical composition. However, these perovskite materials have poor long-term stability due to their sensitivity to moisture. Thus far, various approaches have been attempted to enhance the stability of the perovskite nanocrystals. However, the required level of stability in the mass production process of perovskite nanocrystals under ambient conditions has not been secured. In this work, we developed a facile two-step ball-milling and ethanol/water-induced phase transition method to synthesize stable CsPbBr perovskite materials. We obtained pure CsPbBr perovskite solutions with stability retention of 86% for 30 days under ambient conditions. Our materials show a high PLQY of 35% in solid films, and excellent thermal stability up to 80 °C. We believe that our new synthetic method could be applicable for the mass production of light-emitting perovskite materials.