SAIP2026

Composition-Dependent Electronic and Optical Properties of Ge-Doped CsSnI₃ from First-Principles Calculations

8 Jul 2026, 16:20

1h 20m

Great Hall ( University of the Western Cape)

Poster Presentation Track G - Theoretical and Computational Physics Poster Session 2

Speaker

Dr Neelam Saghir (University of South Africa)

Description

This study presents a first-principles investigation of germanium (Ge)-doped CsSnI₃ perovskites as promising candidates for lead-free photovoltaic applications. With increasing demand for environmentally friendly and high-efficiency solar materials, all-inorganic tin-based perovskites have emerged as viable alternatives to toxic lead-based systems, though their practical implementation is hindered by stability and performance limitations. In this work, density functional theory (DFT) calculations within the CASTEP framework are employed to explore the effects of partial Ge substitution at the Sn site on the structural, electronic, and optical properties of CsSnI₃.
Unlike previous studies that primarily focus on limited doping configurations, this work provides a systematic comparative analysis across multiple Ge doping concentrations, offering deeper insight into composition-dependent electronic behavior. The results reveal that Ge incorporation preserves the perovskite crystal framework while inducing favorable modifications in the electronic structure.
Furthermore, this study establishes a direct correlation between local bonding environments and electronic structure evolution, providing atomistic-level understanding of defect suppression mechanisms induced by Ge doping. Ge incorporation effectively reduces defect states within the bandgap, contributing to improved electronic quality. Optical properties investigations further demonstrate enhanced absorption in the visible region, highlighting the potential of doped systems for efficient light harvesting.
By integrating structural stability, electronic tuning, and optical response within a unified framework, this work offers new insight into the role of B-site engineering in lead-free perovskites beyond conventional performance metrics. Overall, the findings demonstrate that targeted doping serves as an effective strategy to tailor the optoelectronic properties of CsSnI₃ without compromising structural integrity, providing a viable pathway toward the design of high-performance, stable, and environmentally sustainable photovoltaic materials.