This study employs a first-principles approach to comprehensively investigate the structural, electronic, elastic, and optical properties of two distinct inorganic perovskite phases of CsPbI, identified as C–CsPbI and O–CsPbI. Utilizing the Wien2K code, simulations are conducted employing various density functional theory (DFT) approximations, including local density approximation (LDA), generalized gradient approximation (GGA), the modified Becke–Johnson potential (mBJ), and the Tran-Blaha modified Becke–Johnson potential (TB-mBJ). Our analysis demonstrates that the orthorhombic phase exhibits greater energetic stability and mechanical robustness compared to the cubic phase. Furthermore, optical analyses reveal a direct bandgap in the compound, with key parameters calculated and interpreted. Notably, both phases demonstrate exceptional electronic, mechanical, and optical properties, suggesting their potential applications in optoelectronics, photovoltaics, and photovoltaic cells. Consequently, this study positions both the cubic and orthorhombic phases of CsPbI as promising materials warranting further exploration and development in these technological domains.

中文翻译：

---

斜方晶系[公式省略]无机钙钛矿的机械、电子和光学性能从头开始研究

本研究采用第一原理方法全面研究 CsPbI 的两种不同无机钙钛矿相（C-CsPbI 和 O-CsPbI）的结构、电子、弹性和光学性质。利用 Wien2K 代码，采用各种密度泛函理论 (DFT) 近似进行模拟，包括局部密度近似 (LDA)、广义梯度近似 (GGA)、改进的 Becke-Johnson 势 (mBJ) 和 Tran-Blaha 改进的 Becke –约翰逊潜力（TB-mBJ）。我们的分析表明，与立方相相比，斜方相表现出更高的能量稳定性和机械鲁棒性。此外，光学分析揭示了化合物中的直接带隙，并计算和解释了关键参数。值得注意的是，这两个相都表现出优异的电子、机械和光学特性，表明它们在光电子、光伏和光伏电池中的潜在应用。因此，这项研究将立方相和斜方相的 CsPbI 定位为有前途的材料，值得在这些技术领域进行进一步的探索和开发。