AB-INITIO study of electronic, mechanical, optical and thermoelectric properties of KGeCl₃ for photovoltaic application

In this theoretical study, the potential of KGeCl₃ was investigated as a lead-free perovskite active layer for perovskite solar cells. Calculations of the structural, electronic, elastic, optic, and thermoelectric properties of KGeCl₃ in its cubic, tetragonal, and orthorhombic phases were performed using the generalized gradient approximation (GGA) within the wien2k package. The findings demonstrated that the tetragonal crystalline structure of KGeCl3 exhibited the least energy content, rendering it the most thermodynamically stable phase. It was found that the electronic band structure of KGeCl₃ exhibited a direct band gap of 0.92 eV, thus positioning it as a material with promise for utilization as a photovoltaic absorber. Furthermore, the elastic properties of KGeCl₃ were calculated, indicating the presence of suitable mechanical stability for practical applications. Additionally, the optical properties and thermoelectric performance of KGeCl₃ were examined, thereby highlighting its potential for incorporation into thermoelectric devices. In summary, our research showcases how KGeCl₃ holds significant promise as a viable substitute for lead-based perovskite materials in applications such as solar cells and other optoelectronic devices.