ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Structure-dependent mechanical and optical properties of tin-based perovskites for optoelectronic applications: a DFT study

Abhay P. Srivastava and Brijesh K. Pandey

Department of Applied Science and Humanities, Goel Institute of Technology and Management, Lucknow, India

E-mail: abhay.srivastava831@gmail.com

Received: 15 January 2026  Accepted: 9 March 2026

Abstract:

Tin-based hybrid halide perovskites appear to be a promising lead-free solution for next-generation optoelectronic and photovoltaic systems due to their favorable electronic structure, high optical absorption, and low toxicity. We present an in-depth first-principles analysis of orthorhombic methylammonium tin iodide (MASnI₃) and formamidinium tin iodide (FASnI₃) using density functional theory (DFT). Structural, mechanical, thermodynamic, electronic, and optical properties are systematically studied to elucidate the effect of A-site organic cation substitution on lattice stability and functional properties. The performance of the optimised structures is in good agreement with experimental data, supporting the reliability of the computational approach. An analysis of the elastic constant further verifies mechanical stability and manifests strong anisotropy in MASnI₃, while it indicates that FASnI₃ possesses improved elastic isotropy and ductility. The sound velocities and the Debye temperature reveal that lattice stiffness and phonon behavior depend on temperature. Electronic structure calculations, for spin–orbit coupling, show that both compounds are direct-band-gap semiconductors and Sn–I states are predominantly at the band edges. Optical properties such as dielectric behaviour, refractive index, absorption coefficient, and optical conductivity indicate the existence of strong light–matter interactions in the visible and near-infrared regions. Finally, MASnI₃ is better for high absorption and infrared use, and FASnI₃ is better for structural stability and mechanical durability; therefore, it can also be used as a long-time optoelectronic material.

Keywords: Tin-based perovskites; MASnI3; FASnI3; Density functional theory; Mechanical stability; Optoelectronic properties

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-026-04797-3

Chemical Papers 80 (6) 6763–6782 (2026)