The optoelectronic application of CsSnI3 upon substitution with Pb: A DFT approach

Abstract The efficiency of Pb substitution on the Sn site of CsSnI 3 is studied theoretically utilizing DFT as employed by Wien2k code. The energetical, structural, and thermodynamic stability criteria have been fully explained for the studied compounds. Structural and mechanical properties have shown the thermodynamic stability of the studied compounds and their ability to be formed. From their electronic properties, the electronic band gap tuning is observed by systematically substituting Pb in CsSnI 3 . All these compounds (Pb/CsSnI 3 ) have shown a direct band gap nature within the range 1.11–2.95 eV, a potential indication of their possible usage in fabricating solar cells. On further investigating of their optical properties, the most stable and optically active band gap for solar cell application is observed for CsSn 0.75 Pb 0.25 I 3 and CsSn 0.5 Pb 0.5 I 3 . Furthermore, the measured minimum thermal conductivity of Pb/CsSnI 3 is greatest along the [1 1 1] direction. While the direct proportion predicts that the crystal structure with Pb atoms is anharmonic. High melting temperature, thermal stability, a wide optically active region, and a low Debye temperature indicate plausible operable conditions of these compounds under wide ambient conditions. The optical properties, ductile nature, and the bond bending attributes illustrate that CsSn x Pb 1− x I 3 has exciting potential to be used in flexible electronic devices, solar cells, and optical sensors.