Postsynthetic Surface-Treatment of CsPbX₃ (X = Cl, Br, or I) Nanocrystals via CdX₂ Precursor Solution toward High...

The existing defects on the surface of CsPbX₃ nanocrystals (NCs) resulted in the decrease of the photoluminescence quantum yields (PLQYs) of NCs. In this study, we developed a simple strategy, which can make the treated CsPbX₃ NCs exhibit high PLQYs and better stability by CdX₂ post-treatment at room temperature. The treated CsPbX₃ NCs were characterized by X-ray diffraction (XRD) patterns and PL spectra. The shape, size, and crystal structure of the NCs remained unchanged after Cd ion treatment. The PLQYs of CsPbCl₃ increased from 24 to 73% and the PLQYs of CsPbBr₃ NCs increased from 85 to 92% after treatment. The significant enhancement of PLQYs is ascribed to the effective passivation of surface defects, in which Cd²⁺ and X^- ions occupied the Pb-X vacancies existing on the surface of the NCs. In addition, this strategy was also applied to a mixed halide perovskite. The practical application of CsPbX₃ NCs will be extended by this method.