Unraveling the properties of AlSnX3(X=I, Br, Cl) perovskites: A DFT study on optoelectronic and thermoelectric performance

This study employs density functional theory (DFT) to examine the electronic, structural, thermoelectric, and optical properties of AlSnX3 compounds, where X represents the halides iodine (I), bromine (Br), and chlorine (Cl). All materials exhibit indirect bandgaps, with calculated PBE bandgap energies of 1.08 eV, 1.12 eV, and 1.32 eV for AlSnI3, AlSnBr3, and AlSnCl3, respectively. Incorporating spin-orbit coupling (SOC) refines these values to 0.95 eV, 1.08 eV, and 1.29 eV. The hybrid functional approach (HSE+SOC) further enhances the bandgap predictions to 1.32 eV, 1.43 eV, and 1.52 eV, illustrating the computational method's impact on electronic property accuracy. The results highlight the potential of these materials for optoelectronic and solar cell applications. Optical analysis reveals strong light absorption, particularly in AlSnI3, which benefits from a favorable dielectric function and bandgap. Thermoelectric studies indicate promising energy conversion efficiency, with AlSnCl3 exhibiting notable thermoelectric performance at elevated temperatures. Mechanical stability, verified through the Born-Huang criteria, confirms the robustness of these compounds. Elastic property analysis, including bulk and shear moduli, underscores their high resistance to pressure and shear forces. Among the studied materials, AlSnCl3 displays the highest bulk modulus, reflecting superior pressure resistance. Additionally, favorable Pugh's ratios highlight the ductility of these materials, supporting their viability for practical applications.