SAIP2026

Electronic Properties of CH3NH3SnI3: A Density Functional Theory Study Toward Lead-Free Perovskite Solar Cells

7 Jul 2026, 12:20

20m

Lecture Hall GH2 (University of the Western Cape)

Oral Presentation Track B - Nuclear, Particle and Radiation Physics Nuclear, Particle and Radiation Physics -1

Speaker

clarence Mabaso

Description

Organic–inorganic halide perovskites have emerged as promising materials for next-generation photovoltaics due to their tunable band gaps and excellent charge transport properties. Lead-based perovskites such as CH3NH3PbI3 have achieved power conversion efficiencies exceeding 25%, making them strong competitors to conventional silicon solar cells. However, concerns over lead toxicity have driven the search for environmentally friendly alternatives. In this work, a first-principles study of the electronic properties of the lead-free perovskite CH3NH3SnI3 is carried out using density functional theory (DFT) as implemented in CASTEP, employing both LDA and GGA exchange–correlation functionals. The results indicate that CH3NH3SnI3 exhibits a direct band gap in the range of 0.9–1.3 eV (GGA) and 0.6–1.0 eV (LDA), lower than that of CH3NH3PbI3 (~1.55 eV), and closer to the optimal range for photovoltaic applications. The band structure shows strong dispersion near the valence and conduction band edges, suggesting low effective masses and favourable charge carrier mobility. Density of states analysis reveals that I-5p orbitals dominate the valence band maximum, while the conduction band minimum is primarily composed of Sn-5p states. These findings highlight CH3NH3SnI3 as a promising lead-free alternative with suitable electronic properties for photovoltaic applications, while maintaining key advantages associated with lead-based perovskites, CH3NH3SnI3 is still associated with instability.

Keywords: Lead-free perovskites, Density Functional Theory (DFT), Band gap, Solar cells, LDA and GGA functionals