All-inorganic cubic cesium germanium bromide (CsGeBr₃) and cesium tin bromide (CsSnBr₃) perovskites have attracted much attention because of their outstanding optoelectronic properties that lead to many modern technological applications. During their evolution process, it can be helpful to decipher the pressure dependence of structural, optical, electronic, and mechanical properties of CsXBr₃ (X = Ge/Sn) based on ab initio simulations. The lattice parameter and unit cell volume have been decreased by applying pressure. This study reveals that the absorption peak of CsXBr₃ (X = Ge/Sn) perovskites is radically changed toward the lower photon energy region with the applied pressure. In addition, the conductivity, reflectivity, and dielectric constant have an increasing tendency under pressure. The study of electronic properties suggested that CsXBr₃ (X = Ge/Sn) perovskites have a direct energy bandgap. It is also found through the study of mechanical properties that CsXBr₃ (X = Ge/Sn) perovskites are ductile under ambient conditions and their ductility has been significantly improved with pressure. The analysis of bulk modulus, shear modulus, and Young’s modulus reveals that hardness of CsXBr₃ (X = Ge/Sn) perovskites has been enhanced under external pressure. These outcomes suggest that pressure has a significant effect on the physical properties of CsXBr₃ (X = Ge/Sn) perovskites that might be promising for photonic applications.

中文翻译：

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用于光电应用的静水压力处理的环保钙钛矿 CsXBr3(X = Ge/Sn) 的比较研究

全无机立方溴化铯锗 (CsGeBr ₃ ) 和溴化铯锡 (CsSnBr ₃ ) 钙钛矿因其出色的光电特性而备受关注，这导致了许多现代技术应用。在它们的演化过程中，基于ab initio模拟可以帮助破译 CsXBr ₃ (X = Ge/Sn)的结构、光学、电子和机械性能的压力依赖性。通过施加压力，晶格参数和晶胞体积已经减小。该研究表明，CsXBr ₃的吸收峰(X = Ge/Sn) 钙钛矿在施加压力的情况下会朝着较低光子能量区域发生根本性变化。此外，电导率、反射率和介电常数在压力下有增加的趋势。电子特性的研究表明，CsXBr ₃ (X = Ge/Sn) 钙钛矿具有直接的能带隙。通过力学性能研究还发现，CsXBr ₃ (X = Ge/Sn)钙钛矿在环境条件下具有延展性，并且其延展性随着压力的增加而显着提高。体积模量、剪切模量和杨氏模量的分析表明，CsXBr _{3 的}硬度(X = Ge/Sn) 钙钛矿在外部压力下得到增强。这些结果表明压力对 CsXBr ₃ (X = Ge/Sn) 钙钛矿的物理性质有显着影响，这可能有希望用于光子应用。