Perovskite photovoltaics (PVs) have attracted intense interest largely because of their high power conversion efficiency and low cost. The chemical structures of perovskite materials can be generally described by the formula of ABX₃, where cations occupy “A” and “B” sites and anions occupy “X” sites. Herein, we present a comprehensive theoretical study of two inorganic anti-perovskite materials, namely, BiNCa₃ and SbNCa₃, for perovskite PVs. Note that in anti-perovskites, anions occupy “A” and “B” sites, whereas cations occupy “X” sites. Specifically, for both materials, we investigate their thermodynamic stability, dynamic stability, optoelectronic properties and defect properties through ab initio calculations. Our computation suggests that both BiNCa₃ and SbNCa₃ possess direct band gaps of 0.65 and 1.14 eV, respectively. Notably, both materials are predicted to be thermodynamically stable, as demonstrated by their relatively large stable region based on the phase stability analysis. Dynamic and thermal stabilities are also suggested via the computed phonon spectra and ab initio molecular dynamics simulation. Furthermore, both materials possess desired optical absorption coefficients in the visible light region, comparable to that of the prevailing organic–inorganic hybrid perovskite, MAPbI₃. Both exhibit enhanced optical absorption in the infrared region and have good defect tolerance. Lastly, good n-type and p-type conductivity may be realized by controlling the growth condition. The combined desirable properties render both BiNCa₃ and SbNCa₃ as promising all-inorganic and lead-free optical absorbers for PV application.

中文翻译：

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Bi（Sb）NCa ₃：将钙钛矿光伏材料扩展为全无机抗钙钛矿材料

钙钛矿光伏（PVs）吸引了人们极大的兴趣，这是因为它们具有高功率转换效率和低成本。钙钛矿材料的化学结构通常可以用ABX ₃的式子描述，其中阳离子占据“ A”和“ B”位，阴离子占据“ X”位。在此，我们对钙钛矿型PV的两种无机抗钙钛矿材料BiNCa ₃和SbNCa ₃进行了全面的理论研究。注意，在抗钙钛矿中，阴离子占据“ A”和“ B”位，而阳离子占据“ X”位。具体来说，对于这两种材料，我们通过从头算算来研究它们的热力学稳定性，动态稳定性，光电特性和缺陷特性。我们的计算表明，BiNCa₃和SbNCa _3分别具有0.65和1.14eV的直接带隙。值得注意的是，根据相稳定性分析，这两种材料的相对较大的稳定区域证明了这两种材料都具有热力学稳定性。还可以通过计算出的声子谱和从头算分子动力学模拟来建议动态和热稳定性。此外，两种材料在可见光区域均具有所需的光吸收系数，可与流行的有机-无机杂化钙钛矿MAPbI _3相比。。两者在红外区域均表现出增强的光吸收，并且具有良好的缺陷耐受性。最后，通过控制生长条件可以实现良好的n型和p型导电性。组合的理想特性使BiNCa ₃和SbNCa ₃成为用于光伏应用的有前途的全无机无铅光学吸收剂。