Stability and toxicity issues with the hybrid lead iodide perovskite ${\mathrm{MAPbI}}_3$ necessitate a hunt for potential alternatives. Here, we shed light on promising photovoltaic properties of gold mixed-valence halide perovskites ${\mathrm{Cs}}_2{\mathrm{Au}}_2{X}_6$ ($X=\mathrm{I},\mathrm{Br},\mathrm{Cl}$). They satisfy fundamental requirements such as nontoxicity, better stability, a band gap in the visible range, and a low excitonic binding energy. Our study shows a favorable electronic structure, resulting in a high optical-transition strength, and thus a sharp rise in the absorption spectrum near the band gap. This, in turn, yields a very high short-circuit current density and hence higher simulated efficiency compared with ${\mathrm{MAPbI}}_3$. However, careful investigation of defect physics reveals the possibility of deep-level defects (such as $V_X$, $V_{\mathrm{Cs}}$, $X_{\mathrm{Au}}$, $X_{\mathrm{Cs}}$, ${\mathrm{Au}}_i$, and ${\mathrm{Au}}_X$, $X=\mathrm{I},\mathrm{Br}$), depending on the growth conditions. These can act as carrier traps and become detrimental to photovoltaic performance. The present study should help in taking necessary precautions in synthesizing these compounds in a controlled chemical environment, which should minimize performance-limiting defects and pave the way for future studies on this class of materials.

中文翻译：

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无铅光伏吸收剂Cs2AuIAuIIIX6（X = I，Br）的光电特性和缺陷物理

混合碘化铅钙钛矿的稳定性和毒性问题 ${\mathrm{马比}}_3$必须寻找潜在的替代品。在这里，我们阐明了混合价金卤化物钙钛矿的有前途的光伏性能。${\mathrm{Cs}}_2{金}_2{X}_6$ （$X=\mathrm{一世}，溴，氯$）。它们满足诸如无毒，更好的稳定性，在可见光范围内的带隙和低激子结合能之类的基本要求。我们的研究显示出良好的电子结构，导致较高的光学跃迁强度，因此带隙附近的吸收光谱急剧上升。反过来，这产生了很高的短路电流密度，因此与${\mathrm{马比}}_3$。但是，对缺陷物理的仔细研究发现了深层缺陷的可能性（例如$V_X$， $V_{\mathrm{Cs}}$， $X_{金}$， $X_{\mathrm{Cs}}$， ${金}_{\mathrm{一世}}$和 ${金}_X$， $X=\mathrm{一世}，溴$），具体取决于生长条件。这些可以充当载流子陷阱，并且对光伏性能有害。本研究应有助于在受控化学环境中合成这些化合物时采取必要的预防措施，这应将性能受限的缺陷减至最少，并为以后对此类材料的研究铺平道路。