Organic–inorganic halide perovskites are quite promising in applications of large scale photovoltaic technology. However, toxicity is one of the crucial issues in these materials, and searching for environmentally friendly perovskite materials for green energy applications is in high demand. Here we present a systematic ab initio study on the replacement of toxic Pb in the perovskite CH₃NH₃PbI₃ (MAPbI₃) with possible mono- and a few binary replacements. In the mono-replacements study, Ge and Sn are the best alternatives to Pb. In the binary replacements, we replace Pb by mixing Ca/Si and Zn/Si. In case of Ca/Si, a monotonic decrease in band gaps with a monotonic increase in the optical absorption was observed with increasing the Ca concentration. It is observed for the first time that the substitution of Ca/Si (or Zn/Si) at the B-site with various ratios would lead to remarkably high device absorption efficiencies. The band gaps of the studied mixed replacements are in the ideal ranges for single-junction solar cell and one cell in tandem architecture. As a result of the smaller effective masses, the mixed replacements could have better carrier mobility. An ab initio molecular dynamic simulation demonstrates the stability of the mixed replacements. More importantly, the mixed substituting elements are highly abundant in the earth. This work is helpful to gain further insights into developing green solar cells with low cost and high performance and would lead to wide applications in the future.

中文翻译：

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预测用于太阳能电池的无铅钙钛矿

有机-无机卤化物钙钛矿在大规模光伏技术的应用中非常有前途。然而，毒性是这些材料中的关键问题之一，因此迫切需要寻找绿色钙钛矿材料用于绿色能源。这里，我们提出一个系统的从头研究在钙钛矿CH更换毒性的Pb ₃ NH ₃碘化铅₃（MAPbI ₃），并且可能会替换为单个和一些二进制文件。在单取代研究中，Ge和Sn是Pb的最佳替代品。在二元替代中，我们通过混合Ca / Si和Zn / Si替代Pb。在Ca / Si的情况下，随着Ca浓度的增加，观察到带隙的单调减少和光吸收的单调增加。首次观察到以各种比例替换B位处的Ca / Si（或Zn / Si）会导致极高的器件吸收效率。所研究的混合替代物的带隙在单结太阳能电池和串联结构中的一个电池的理想范围内。由于较小的有效质量，混合的替代物可以具有更好的载流子迁移率。从头算分子动力学模拟证明了混合代用品的稳定性。更重要的是，混合替代元素在地球上非常丰富。这项工作有助于深入了解开发低成本和高性能的绿色太阳能电池，并将在未来得到广泛的应用。