Sarker Md Amran, Hasan Md Mehedi, Momin Md Al, Irfan Ahmad, Islam Md Rasidul, Sharif Ahmed
Department of Materials and Metallurgical Engineering, Bangladesh University of Engineering & Technology (BUET) Dhaka Bangladesh
Department of Materials Science and Engineering, Khulna University of Engineering & Technology (KUET) Khulna 9203 Bangladesh.
RSC Adv. 2024 Mar 25;14(14):9805-9818. doi: 10.1039/d4ra00224e. eCollection 2024 Mar 20.
Lead-free inorganic Ge-based perovskites GaGeX (X = Cl, Br, and I) are promising candidates for solar cell applications due to their structural, mechanical, electrical, and optical properties. In this work, we performed density functional theory (DFT) calculations using the CASTEP module to investigate these properties in detail. We found that the lattice parameters and cell volumes increase with the size of the halogen atoms, and that all the compounds are stable and ductile. GaGeBr has the highest ductility, machinability, and lowest hardness, while GaGeCl has the highest anisotropy. The band gap values, calculated using the GGA-PBE and HSE06 functionals, show a direct band gap at the R-R point, ranging from 0.779 eV and 1.632 eV for GaGeCl to 0.330 eV and 1.140 eV for GaGeI. The optical properties, such as absorption coefficient, conductivity, reflectivity, refractive index, extinction coefficient, and dielectric function, are also computed and discussed. We observed that the optical properties improve with the redshift of the band gap as Cl is replaced by Br and I. GaGeI has the highest dielectric constant, indicating the lowest recombination rate of electron-hole pairs. Our results suggest that GaGeX (X = Cl, Br, and I) can be used as effective and non-toxic materials for multijunction solar cells and other semiconductor devices.
无铅无机锗基钙钛矿GaGeX（X = Cl、Br和I）因其结构、机械、电学和光学性质，是太阳能电池应用的有前景的候选材料。在这项工作中，我们使用CASTEP模块进行了密度泛函理论（DFT）计算，以详细研究这些性质。我们发现晶格参数和晶胞体积随卤原子尺寸的增加而增大，并且所有化合物都是稳定且具有延展性的。GaGeBr具有最高的延展性、可加工性和最低的硬度，而GaGeCl具有最高的各向异性。使用GGA-PBE和HSE06泛函计算的带隙值在R-R点显示出直接带隙，范围从GaGeCl的0.779 eV和1.632 eV到GaGeI的0.330 eV和1.140 eV。还计算并讨论了光学性质，如吸收系数、电导率、反射率、折射率、消光系数和介电函数。我们观察到随着Cl被Br和I取代，带隙红移，光学性质得到改善。GaGeI具有最高的介电常数，表明电子-空穴对的复合率最低。我们的结果表明，GaGeX（X = Cl、Br和I）可以用作多结太阳能电池和其他半导体器件的有效且无毒的材料。
