Compositional engineering, which can enrich the database of prospective materials and offer new or enhanced properties, represents one of the key focal points within halide perovskite research. Compositional engineering studies often focus on A⁺ and X^– site substitutions, within the ABX₃ perovskite structure, due to the relative ease of varying these sites. However, alloying on the B site can play a more important role in generating novel properties and decreasing Pb toxicity for Pb-based systems. To date, B site substitution has primarily been confined to single-element alloying. Herein, a heterovalent co-alloying strategy for the B site of halide perovskites is proposed. Ag^IBi^III and Ag^ISb^III are co-alloyed into a host crystal of APbBr₃ (A = Cs and methylammonium), leading to a larger range of prospective alloying elements on the perovskite B site. Density functional theory-based first-principles calculations provide a possible rational for the red shift of the bandgap and blue shift of the photoluminescence (PL) in the alloying experiments.

中文翻译：

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卤化物钙钛矿带隙工程的异质B站点共合金方法

成分工程可以丰富潜在材料的数据库并提供新的或增强的性能，是卤化物钙钛矿研究的重点之一。组成工程研究往往集中在一个⁺和X ^-现场换人，ABX内₃钙钛矿结构，由于相对容易改变这些网站。但是，在基于Pb的系统中，B位上的合金化在产生新特性和降低Pb毒性方面可以发挥更重要的作用。迄今为止，B位取代主要限于单元素合金化。本文提出了卤化物钙钛矿B位的异价共合金策略。Ag ^I Bi ^III和Ag ^ISb ^III共合金到APbBr ₃（A = Cs和甲基铵）的主体晶体中，从而在钙钛矿B位点上产生了范围更大的预期合金元素。基于密度泛函理论的第一性原理计算为合金化实验中带隙的红移和光致发光（PL）的蓝移提供了可能的合理性。