Studying temperature effects on electronic and optical properties of cubic CH₃NH₃SnI₃ perovskite

CH₃NH₃SnI₃ is a promising lead-free perovskite structure for the absorber layer in solar cells. In this work, for the first time, we simulated the effect of temperature change on the electronic and optical properties of CH₃NH₃SnI₃ through a combination of the molecular dynamics and density functional theory methods. We report the results of our studies on the electronic and optical properties of the normal (300 K) and expanded (325 K)/contracted (275 K) CH₃NH₃SnI₃ structures, and compare the obtained results with each other. Our electronic calculations showed that the direct band gap is opened up to 1.02 eV, 1.25 eV, and 0.88 eV for the normal and thermally expanded/contracted structures, respectively. The calculated density of states for all the structures shows that the Sn and I ions play an important role in the electronic properties of the studied samples, and methyl ammonium (CH₃NH₃) is a structural framework for this perovskite. The absorption, transparency, and maximum reflectivity to the considered energies indicate the potential of CH₃NH₃SnI₃ for optoelectronic applications. The obtained results also show that the CH₃NH₃SnI₃ perovskite, as an absorber layer in solar cells, exhibits a better optical performance at 325 K than at 275 K and 300 K.