Perovskite-related Cs₄PbBr₆ nanocrystals present a “zero-dimensional” crystalline structure where adjacent [PbBr₆]^4– octahedra do not share any corners. We show in this work that these nanocrystals can be converted into “three-dimensional” CsPbBr₃ perovskites by extraction of CsBr. This conversion drastically changes the optoelectronic properties of the nanocrystals that become highly photoluminescent. The extraction of CsBr can be achieved either by thermal annealing (physical approach) or by chemical reaction with Prussian Blue (chemical approach). The former approach can be simply carried out on a dried film without addition of any chemicals but does not yield a full transformation. Instead, reaction with Prussian Blue in solution achieves a full transformation into the perovskite phase. This transformation was also verified on the iodide counterpart (Cs₄PbI₆).

中文翻译：

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通过物理和化学萃取CsBr将合成的Cs ₄ PbBr ₆纳米晶体合成为明亮的钙钛矿CsPbBr ₃

与钙钛矿相关的Cs ₄ PbBr ₆纳米晶体呈现“零维”晶体结构，其中相邻的[PbBr ₆ ] ^4–八面体不共享任何角。我们在这项工作中表明，这些纳米晶体可以转化为“三维” CsPbBr _3。通过萃取CsBr得到钙钛矿。该转换极大地改变了变成高度光致发光的纳米晶体的光电特性。可以通过热退火（物理方法）或通过与普鲁士蓝的化学反应（化学方法）来实现CsBr的提取。前一种方法可以简单地在干燥膜上进行而无需添加任何化学药品，但不会产生完全的转化。相反，与普鲁士蓝在溶液中的反应可实现向钙钛矿相的完全转化。此转变也已在碘化物对应物（Cs ₄ PbI ₆）上验证。