Abstract

Hybrid organic-inorganic halide perovskites as promising solar cell materials have great concern on their stability. Recently, all-inorganic perovskite CsPbI₂Br has been considered as a first-class alternative with good stability as well as a suitable bandgap, and the highest solar cell efficiency has been achieved up to 16%. Using the first-principles calculations, we found that (i) CsPbI₂Br is stable in tetragonal cell with a direct bandgap of 1.67 eV under PBE functional calculations approximating to the experimental value (1.92 eV). The upper valence band is derived from the antibonding states of s-p coupling, and the CBM is mainly composed of Pb-p states. (ii) The optical absorption is as strong as 10⁴ cm⁻¹ in the visible light range which can compare to that of the popular halide organic-inorganic hybrid perovskite. (iii) The electron transport material (ETM) in popular perovskite solar cells such as TiO₂, ZnO, SnO₂, PCBM and C₆₀ together with the hole transport material (HTM) such as P3HT, CuI, NiO, PTAA and Spiro are suitable for CsPbI₂Br solar cell devices. The band offset between different perovskites demonstrates that it is easier for CsPbI₂Br to be doped p-type than for CsPbBr₃ but harder than for CsPbI₃.

Graphic Abstract

Band alignments of perovskites including CsPbI₃, CsPbBr₃, CsPbI₂Br and CsSnI₂Br together with the commonly used electron transport materials and hole transport materials are presented using the first principles calculations, which could help to improve the all inorganic CsPbI₂Br solar cell performance.

中文翻译：

---

全无机钙钛矿CsPbI 2 Br作为有前途的光伏吸收剂：一项第一性原理研究

摘要

混合有机-无机卤化物钙钛矿作为有前途的太阳能电池材料对其稳定性非常关注。近来，全无机钙钛矿CsPbI ₂ Br被认为是具有良好稳定性和合适带隙的一流替代品，最高太阳能电池效率已达到16％。使用第一性原理计算，我们发现（i）CsPbI ₂ Br在四方晶胞中稳定，在PBE功能计算下的直接带隙为1.67 eV，近似于实验值（1.92 eV）。高价带是从sp偶合的反键态导出的，CBM主要由Pb-p态组成。（ii）光吸收高达10 ⁴  cm ^-1在可见光范围内可以与流行的卤化物有机-无机杂化钙钛矿相比较。（iii）常见的钙钛矿太阳能电池（如TiO ₂，ZnO，SnO ₂，PCBM和C ₆₀）中的电子传输材料（ETM）以及P3HT，CuI，NiO，PTAA和Spiro等空穴传输材料（HTM）为适用于CsPbI ₂ Br太阳能电池器件。不同钙钛矿之间的能带偏移表明，CsPbI ₂ Br的掺杂比CsPbBr _3的掺杂为p型，但比CsPbI _3的掺杂更难。

图形摘要

使用第一原理计算方法，给出了钙钛矿包括CsPbI ₃，CsPbBr ₃，CsPbI ₂ Br和CsSnI ₂ Br的能带排列以及常用的电子传输材料和空穴传输材料，这可以帮助改善所有无机CsPbI ₂ Br太阳能电池性能。