Colloidal ALD Epitaxial Shelling Enhances Stability and Photoluminescence of Blue Perovskite Nanocrystals

A modified colloidal atomic layer deposition at room temperature grows a vacancy-ordered Cs2SnCl6 shell epitaxially on CsPbCl3 nanocrystals, avoiding the core degradation and parasitic shell nucleation that accompany high-temperature routes. The resulting core–shell nanocrystals achieve an absolute photoluminescence quantum yield of 62% and retain 65% of their emission after six months of ambient storage and 30% after 48 h of exposure to added water.