Publication date: 21st July 2025
Tin-halide perovskites have recently emerged as the most promising non-toxic candidates to replace lead-halide materials in photovoltaic devices, offering comparable efficiency without the use of toxic Pb.[1] Nevertheless, research on Sn-based perovskites has almost exclusively concentrated on iodide-only systems, restricting the ability to tune the bandgap. Achieving a controllable iodide/bromide ratio is critical to exploit the composition-dependent bandgap engineering that makes halide perovskites particularly suitable for high-performance solar cells. In this work, we focus on the development of mixed-halide FA0.98EDA0.01SnI3-xBrx thin films by partially substituting FAI with FABr and/or SnI2 with SnBr2. We systematically investigate crystallization dynamics, film formation, and stability under different processing conditions. Optical absorption and photoluminescence measurements are employed to determine the bandgap and establish its relationship with halide composition. Furthermore, the intrinsic optoelectronic quality of the resulting materials is assessed via quasi-Fermi level splitting measurements, providing direct insight into recombination losses. Based on these results, solar cell devices will be fabricated using the most promising compositions to evaluate their photovoltaic performance. This study aims to define clear composition–processing–property relationships and to advance Sn-based perovskites toward efficient, bandgap-tunable, and environmentally sustainable photovoltaic technologies.
Molecular Materials and Nanosystems Group (m2ngroup.nl)