The air-stable, low-toxicity double perovskite structure ${\mathrm{\text{Cs}}}_2{\mathrm{\text{SnX}}}_6$ (X = Cl, Br and I) has attracted great attention due to its excellent potential in optoelectronic and photovoltaic applications. We used density functional theory to theoretically study the pressure response mechanism of double perovskite ${\mathrm{\text{Cs}}}_2{\mathrm{\text{SnX}}}_6$. The results show that pressure can effectively regulate the electronic structure and optical absorption properties of ${\mathrm{\text{Cs}}}_2{\mathrm{\text{SnX}}}_6$. When subjected to hydrostatic pressure ranging from 0 to 50 GPa, the bandgaps of ${\mathrm{\text{Cs}}}_2{\mathrm{\text{SnCl}}}_6$, ${\mathrm{\text{Cs}}}_2{\mathrm{\text{SnBr}}}_6$ and ${\mathrm{\text{Cs}}}_2{\mathrm{\text{SnI}}}_6$ all exhibit a phenomenon of first decreasing and then increasing during the change. ${\mathrm{\text{Cs}}}_2{\mathrm{\text{SnI}}}_6$ exhibits semimetallic properties when the valence band and conduction band begin to overlap under hydrostatic pressure of 2 GPa or higher. In addition, with increasing pressure, the optical absorption peak of ${\mathrm{\text{Cs}}}_2{\mathrm{\text{SnX}}}_6$ shows a significant blue shift, and the absorption coefficient in the visible and near-infrared regions gradually increases. When a uniaxial pressure is applied to ${\mathrm{\text{Cs}}}_2{\mathrm{\text{SnX}}}_6$ crystal, it significantly reduces in one direction and expands in the other two perpendicular directions. The structure changes from cubic phase to tetragonal phase. The optical absorption coefficient in the direction of pressure first increases and the others decrease.

空气稳定、低毒的双钙钛矿结构${\mathrm{\text{CS}}}_2{\mathrm{\text{锡X}}}_6$（X=Cl、Br和I）由于其在光电和光伏应用中的优异潜力而引起了极大的关注。我们利用密度泛函理论从理论上研究了双钙钛矿的压力响应机制${\mathrm{\text{CS}}}_2{\mathrm{\text{锡X}}}_6$。结果表明，压力可以有效调控电子结构和光吸收特性。${\mathrm{\text{CS}}}_2{\mathrm{\text{锡X}}}_6$。当受到 0 至 50 GPa 的静水压力时，带隙为${\mathrm{\text{CS}}}_2{\mathrm{\text{氯化亚锡}}}_6$,${\mathrm{\text{CS}}}_2{\mathrm{\text{溴化锡}}}_6$和${\mathrm{\text{CS}}}_2{\mathrm{\text{碘化锡}}}_6$变化过程中均呈现先减少后增加的现象。${\mathrm{\text{CS}}}_2{\mathrm{\text{碘化锡}}}_6$当价带和导带在 2 GPa 或更高的静水压力下开始重叠时，表现出半金属特性。此外，随着压力的增加，光吸收峰${\mathrm{\text{CS}}}_2{\mathrm{\text{锡X}}}_6$表现出明显的蓝移，并且在可见光和近红外区域的吸收系数逐渐增大。当单轴压力施加到${\mathrm{\text{CS}}}_2{\mathrm{\text{锡X}}}_6$晶体中，它在一个方向上显着缩小，在另外两个垂直方向上显着膨胀。结构由立方相转变为四方相。压力方向的光吸收系数先增大，其余减小。