Strain-Driven Optical, Electronic, and Mechanical Properties of Inorganic Halide Perovskite CsGeBr <sub>3</sub>
Md. Rasidul Islam, Md. Rayid Hasan Mojumder, Raza Moshwan, A. S. M. Jannatul Islam, M. A. Islam, Md. Shizer Rahman, Md. Humaun Kabir
Abstract
Of late, inorganic perovskite material, especially the lead-free CsGeBr 3, has gained considerable interest in the green photovoltaic industry due to its outstanding optoelectronic, thermal, and elastic properties. This work systematically investigated the strain-driven optical, electronic, and mechanical properties of CsGeBr 3 through the first-principles density functional theory. The unstrained planar CsGeBr 3 compound demonstrates a direct bandgap of 0.686 at its R-point. However, incorporating external biaxial tensile (compressive) strain can be tuned the bandgap lowering (increasing) to this perovskite. Moreover, due to the increase of tensile (compressive) strain, a red-shift (blue-shift) behavior of the absorption-coefficient and dielectric function is found in the photon energy spectrum. Strain-induced mechanical properties also reveal that CsGeBr 3 perovskites are mechanically stable and highly malleable material and can be made suitable for photovoltaic applications. The strain-dependent optoelectronic and mechanical behaviors of CsGeBr 3 explored here would benefit its future applications in optoelectronics and photovoltaic cells design.