Ligand-assisted reprecipitation strategy (LARS) is one of the most popular methods for the fabrication of lead halide perovskite nanocrystals; however, it has always been criticized for poor repeatability and low stability of the resulting nanocrystals. Herein, we demonstrate that liquefying MAPbBr₃ single crystals via methylamine (MA) gas rather than being dissolved in N,N-dimethylformamide (DMF) are more beneficial in synthesizing high-quality and stable MAPbX₃ (X = Cl, Br, I) based on the LARS. In particular, the liquefied single-crystal-derived MAPbBr₃ nanocrystals show a high PLQY exceeding 95%, while 87% for the one derived from the traditional LARS. It is found that replacing DMF solvent with MA gas can not only passivate the MA vacancy defects on the nanocrystal surface but also hinder the formation of halide vacancies, both of which significantly enhance the stability. Benefitting from the impressive PLQY and high X-ray attenuation, MAPbBr₃ nanocrystals exhibit strong radioluminescence under X-ray excitation, which further enables their application in large-area X-ray imaging. Furthermore, liquefied perovskite single crystals can be further applied in the in situ synthesis of MAPbX₃ nanocrystals within the mesoporous SiO₂ template, affording the MAPbX₃@SiO₂ complex, which exhibits potential as stable solid-state light-emitting diodes.

中文翻译：

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通过甲胺-MAPbBr ₃液体的再沉淀获得MAPbBr ₃纳米晶体的高光致发光量子产率（> 95％）

配体辅助的再沉淀策略（LARS）是制造卤化钙钛矿型纳米晶体的最流行方法之一。然而，人们一直批评所得纳米晶体的可重复性差和稳定性差。本文中，我们证明了通过甲胺（MA）气体而不是溶解于N，N-二甲基甲酰胺（DMF）液化MAPbBr ₃单晶在合成高质量且稳定的MAPbX ₃（X = Cl，Br，I）方面更为有益。基于LARS。尤其是液化的单晶MAPbBr ₃纳米晶体的PLQY超过95％，而传统LARS的PLQY高达87％。发现用MA气体代替DMF溶剂不仅可以钝化纳米晶体表面上的MA空位缺陷，而且可以阻碍卤化物空位的形成，这两者都显着增强了稳定性。得益于令人印象深刻的PLQY和高X射线衰减，MAPbBr ₃纳米晶体在X射线激发下显示出强大的放射致发光特性，这进一步使其能够在大面积X射线成像中应用。此外，可以将液化钙钛矿单晶进一步应用于介孔SiO ₂模板内的MAPbX ₃纳米晶体的原位合成中，得到MAPbX ₃ @SiO ₂ 具有稳定的固态发光二极管潜力的复合物。