In our work, the lead-free double-perovskite RbAgBiX (X = Cl, Br, I) has been executed as well as examined by ab-initio computations for solar cell and photocatalytic applications. These results indicate that RbAgBiX (X = Cl, Br, I) compound has remarkable structural stability and formability, as evidenced by their structural factor, formation energy and mechanical properties. The lower Young's modulus values suggest that these materials can be more easily converted into thin films required for flexible solar cell devices. The calculated bandgap values of RbAgBiCl (2.86 eV), RbAgBiBr (2.17 eV) and RbAgBiI (1.49 eV) disclosed their indirect nature. Moreover, the effective mass of charge carrier in these compounds is relatively small, and the effective mass of hole (m*) is larger than that of electron (m*), resulting in higher carrier mobility and lower carrier recombination rate. The calculated optical properties indicate that RbAgBiX (X = Cl, Br, I) has significant light absorption in the ultraviolet and visible light ranges and the absorption peak coefficient can reach ∼10/cm. Finally, the photocatalytic properties are mainly confirmed by the redox potential and carrier recombination rate of these studied materials. Notably, RbAgBiCl and RbAgBiBr have better photocatalytic activity. Therefore, theoretical calculations suggest that RbAgBiX (X = Cl, Br, I) double perovskite has great application potential in solar cell and photocatalytic fields.

中文翻译：

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双钙钛矿 Rb2AgBiX6（X = Cl、Br、I）在太阳能电池和光催化应用中的理论研究

在我们的工作中，无铅双钙钛矿 RbAgBiX（X = Cl、Br、I）已通过太阳能电池和光催化应用的从头计算进行了执行和检查。这些结果表明，RbAgBiX (X = Cl, Br, I) 化合物具有显着的结构稳定性和成型性，其结构因素、形成能和机械性能证明了这一点。较低的杨氏模量值表明这些材料可以更容易地转化为柔性太阳能电池器件所需的薄膜。 RbAgBiCl (2.86 eV)、RbAgBiBr (2.17 eV) 和 RbAgBiI (1.49 eV) 的计算带隙值揭示了它们的间接性质。而且，这些化合物中载流子的有效质量相对较小，空穴的有效质量（m*）大于电子的有效质量（m*），从而导致较高的载流子迁移率和较低的载流子复合率。计算的光学性质表明RbAgBiX (X = Cl, Br, I)在紫外和可见光范围内具有显着的光吸收，吸收峰系数可达∼10/cm。最后，光催化性能主要通过这些研究材料的氧化还原电位和载流子复合率来证实。值得注意的是，RbAgBiCl和RbAgBiBr具有更好的光催化活性。因此，理论计算表明RbAgBiX(X=Cl、Br、I)双钙钛矿在太阳能电池和光催化领域具有巨大的应用潜力。