Role of halide substitution in K2SiX6 (X = F, cl, Br) perovskites: first-principles insights for sustainable solar cell materials

IF 2.4 3区化学 Q4 CHEMISTRY, PHYSICAL

Chemical Physics Pub Date : 2025-10-10 DOI:10.1016/j.chemphys.2025.112964

Md. Ferdous Rahman , Sirat-E-Azmin Shifa , Tanvir Al Galib , Ahmad Irfan , Aijaz Rasool Chaudhry , Md. Atikur Rahman , Md. Faruk Hossain

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Abstract

The development of eco-friendly, lead-free perovskites has motivated exploration of vacancy-ordered double perovskites K₂SiX₆ (X = F, Cl, Br). Using DFT with GGA-PBE and HSE06, their structural, electronic, vibrational, mechanical, and optical properties are systematically analyzed. All compounds stabilize in the cubic Fm-3 m phase with tolerance factors within the perovskite stability window. Negative formation energies and phonon spectra without imaginary modes confirm chemical and dynamic stability. Mechanical analysis indicates elastic stability across the series, with K₂SiBr₆ showing the highest stiffness, bulk modulus, and ductility (B/G = 3.015), ensuring strong structural resilience. Electronic calculations reveal a direct 1.14 eV bandgap for K₂SiBr₆, ideally aligned with the Shockley–Queisser efficiency limit. Optical studies highlight enhanced visible absorption, a favorable dielectric constant (ε₁(0) = 5.13), and the lowest energy loss, minimizing recombination. Overall, halide substitution tunes properties, positioning K₂SiBr₆ as a stable, robust, and efficient lead-free candidate for future solar cell applications.

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卤化物取代在K2SiX6 （X = F, cl, Br）钙钛矿中的作用：可持续太阳能电池材料的第一性原理见解

环保型无铅钙钛矿的发展推动了空位有序双钙钛矿k2six₆（X = F, Cl, Br）的探索。利用DFT对GGA-PBE和HSE06进行分析，系统地分析了它们的结构、电子、振动、力学和光学特性。所有化合物都稳定在立方的fm - 3m相中，在钙钛矿稳定性窗口内具有容差因子。负的形成能和没有虚模的声子谱证实了化学和动态稳定性。力学分析表明，整个系列的弹性稳定，其中K₂SiBr货号的刚度、体积模量和延展性最高（B/G = 3.015），确保了强大的结构弹性。电子计算显示K₂SiBr₆的直接带隙为1.14 eV，理想地符合Shockley-Queisser效率限制。光学研究强调了增强的可见光吸收，有利的介电常数（ε 1(0) = 5.13）和最低的能量损失，最大限度地减少了复合。总体而言，卤化物替代调整了性能，将K₂SiBr₆定位为未来太阳能电池应用的稳定，坚固，高效的无铅候选产品。

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来源期刊

Chemical Physics 化学-物理：原子、分子和化学物理

CiteScore

4.60

自引率

4.30%

发文量

278

审稿时长

39 days

期刊介绍： Chemical Physics publishes experimental and theoretical papers on all aspects of chemical physics. In this journal, experiments are related to theory, and in turn theoretical papers are related to present or future experiments. Subjects covered include: spectroscopy and molecular structure, interacting systems, relaxation phenomena, biological systems, materials, fundamental problems in molecular reactivity, molecular quantum theory and statistical mechanics. Computational chemistry studies of routine character are not appropriate for this journal.