Postsynthetic Surface-Treatment of CsPbX (X = Cl, Br, or I) Nanocrystals via CdX Precursor Solution toward High Photoluminescence Quantum Yield.

The existing defects on the surface of CsPbX 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 CsPbX NCs exhibit high PLQYs and better stability by CdX post-treatment at room temperature. The treated CsPbX 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 CsPbCl increased from 24 to 73% and the PLQYs of CsPbBr NCs increased from 85 to 92% after treatment. The significant enhancement of PLQYs is ascribed to the effective passivation of surface defects, in which Cd 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 CsPbX NCs will be extended by this method.