The lead-free double perovskite material (viz. Cs₂AgBiCl₆) has emerged as an efficient and environmentally friendly alternative to lead halide perovskites. To make Cs₂AgBiCl₆ optically active in the visible region of solar spectrum, band gap engineering approach has been undertaken. Using Cs₂AgBiCl₆ as a host, band gap and optical properties of Cs₂AgBiCl₆ have been modulated by alloying with M(I), M(II), and M(III) cations at Ag-/Bi-sites. Here, we have employed density functional theory (DFT) with suitable exchange-correlation functionals in light of spin–orbit coupling (SOC) to determine the stability, band gap and optical properties of different compositions, that are obtained on Ag–Cl and Bi–Cl sublattices mixing. On analyzing 64 combinations within Cs₂AgBiCl₆, we have identified 19 promising configurations having band gap sensitive to solar cell applications. The most suitable configurations with Ge(II) and Sn(II) substitutions have spectroscopic limited maximum efficiency (SLME) of 32.08% and 30.91%, respectively, which are apt for solar cell absorber.

无铅双钙钛矿材料（即 Cs ₂ AgBiCl ₆）已成为卤化铅钙钛矿的一种高效且环保的替代品。为了使 Cs ₂ AgBiCl ₆在太阳光谱的可见光区具有光学活性，已采用带隙工程方法。使用CS ₂ AgBiCl ₆作为宿主时，带隙和Cs的光学性质₂ AgBiCl ₆已通过在 Ag-/Bi 位点与 M(I)、M(II) 和 M(III) 阳离子合金化进行调制。在这里，我们根据自旋轨道耦合 (SOC) 使用具有合适交换相关泛函的密度泛函理论 (DFT) 来确定在 Ag-Cl 和 Bi 上获得的不同成分的稳定性、带隙和光学性质-Cl 亚晶格混合。在分析 Cs ₂ AgBiCl ₆内的 64 种组合时，我们确定了 19 种具有对太阳能电池应用敏感的带隙的有前途的配置。Ge(II) 和 Sn(II) 取代的最合适的配置分别具有 32.08% 和 30.91% 的光谱极限最大效率 (SLME)，适用于太阳能电池吸收剂。