Halide perovskites, such as methylammonium lead halide perovskites (${\mathrm{MAPbX}}_3$, $\mathrm{X}=\mathrm{I}$, Br, and Cl), are emerging as promising candidates for a wide range of optoelectronic applications, including solar cells, light-emitting diodes, and photodetectors, due to their superior optoelectronic properties. All-inorganic lead halide perovskites ${\mathrm{CsPbX}}_3$ are attracting a lot of attention because replacing the organic cations with ${\mathrm{Cs}}^{+}$ enhances the stability, and its halide-mixing derivatives offer broad bandgap tunability covering nearly the entire visible spectrum. However, there is evidence suggesting that the optical properties of mixed-halide perovskites are influenced by phase segregation under external stimuli, especially illumination, which may negatively impact the performance of optoelectronic devices. It is reported that the mixed-halide perovskites in forms of thin films and nanocrystals are segregated into a low-bandgap I-rich phase and a high-bandgap Br-rich phase. Herein, we present a critical review on the synthesis and basic properties of all-inorganic perovskites, phase-segregation phenomena, plausible mechanisms, and methods to mitigate phase segregation, providing insights on advancing mixed-halide perovskite optoelectronics with reliable performance.

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无机混合卤化物钙钛矿中的相偏析：从现象到机理

卤化钙钛矿，例如甲基铵卤化钙钛矿（${\mathrm{MAPbX}}_3$， $\mathrm{X}=\mathrm{一世}$，Br和Cl），由于其优异的光电性能，正成为包括太阳能电池，发光二极管和光电探测器在内的各种光电应用的有希望的候选者。全无机卤化铅钙钛矿${\mathrm{CsPbX}}_3$ 正引起人们的广泛关注，因为用 ${\mathrm{Cs}}^{+}$增强了稳定性，其卤化物混合衍生物提供了几乎覆盖整个可见光谱的宽带隙可调性。但是，有证据表明，混合卤化物钙钛矿的光学特性受外部刺激（尤其是照明）下的相分离的影响，这可能会对光电器件的性能产生负面影响。据报道，薄膜和纳米晶体形式的混合卤化物钙钛矿被分离成低带隙富I相和高带隙富Br相。在本文中，我们对全无机钙钛矿的合成和基本性质，相分离现象，合理的机理以及减轻相分离的方法进行了严格的综述，从而为推进具有可靠性能的混合卤化物钙钛矿光电技术提供了见识。