Research group of Dr. Haizheng Zhong from Beijing Institute of Technology made progress on halide perovskite quantum dots and published their work on Chem. Mater..

The stability of perovskites is the most concerned issue for their fundamental study and device exploration. Especially, iodide-based CH3NH3PbI3 quantum dots are very sensitive to moisture. Even in the glove box, the colloidal CH3NH3PbI3 quantum dots obtained from N, N-dimethylformamide suffer from instability caused by fast degradation within days to weeks. In this work, we investigated the interactions between perovskite precursors and various polar solvents as well as their influence on the crystallization of CH3NH3PbI3 in reprecipitation synthesis. By gaining chemical insight into the coordination effects, we discovered that the residual coordinated solvents in the resulting crystals on the surface mainly contributed to the degradation of CH3NH3PbI3. On the basis of this understanding, we fabricated air-stable CH3NH3PbI3 quantum dots with a tunable size from 6.6 to 13.3 nm by selecting noncoordinated acetonitrile as a good solvent through ligand-assisted precipitation synthesis. With these air stable samples, we demonstrated the quantum confinement effects in CH3NH3PbI3 quantum dots by correlating the size-dependent photoluminescence properties with theoretical calculations.

The link of the full paper can be found at: http://pubs.acs.org/doi/abs/10.1021/acs.chemmater.7b01100

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