Combining Material Chemistry and Device Physics for High-Performance Perovskite Photovoltaics

Advancing the efficiency and operational stability of perovskite solar cells (PSCs) requires both improved material design and deeper insight into device physics. One approach to address the inherent instability of tin-based PSCs involves the incorporation of thiophene-ethylammonium halides (TEAX) into FASnI₃ perovskite formulations. These additives modulate crystallization dynamics and inhibit Sn²⁺ oxidation through sulfur-tin coordination, leading to enhanced film morphology, reduced non-radiative recombination, and extended device lifetimes. TEABr-treated devices, in particular, exhibited significant gains in performance and retained over 95% of their initial power conversion efficiency after 2000 h of continuous illumination. Complementing this materials-level advancement, impedance spectroscopy combined with current-voltage (j-V) curve reconstruction offers a powerful tool to isolate the impact of recombination resistance in PSCs. By correlating impedance-derived parameters with j-V behavior, it becomes possible to assess when recombination is the dominant loss mechanism, particularly in devices with unhindered charge extraction. This methodology enables a clearer differentiation between transport, extraction, and recombination processes; critical for both optimizing device architecture and interpreting spectral features in complex systems. Together, these findings contribute to a more robust framework for both the design and analysis of high-performance perovskite photovoltaics.