Deciphering the interplay between tin vacancies and free carriers in the ion transport of tin-based perovskites
Huerta Hernandez, L.; Lanzetta, L.; Kotowska, A. M.; Yavuz, I.; Kalasariya, N.; Vishal, B.; Gibert-Roca, M.; Piggott, M.; Scurr, D. J.; De Wolf, S.; Stolterfoht, M.; Baran, D. Energy Environ. Sci. 2025, DOI: 10.1039/d5ee00632e.
The main goal of this study was to uncover how tin vacancies (VSn²⁻) and free holes (h⁺) jointly influence ion transport in tin-based perovskites, with implications for improving device stability and performance.
Key findings show that increasing the Sn content in ASnxPb₁₋ₓI₃ perovskites raises both electronic and ionic conductivity. Higher VSn²⁻ and hole concentrations enhance ion migration by lowering the energy barrier for iodide diffusion (from 0.38 eV to 0.12 eV). Experimental techniques, including galvanostatic polarization and capacitance–voltage measurements, confirmed that mobile ion density and hole density are coupled. First-principles calculations and chemical mapping directly linked VSn²⁻ and h⁺ to accelerated ion migration. Devices with higher Sn content suffered greater bias-induced degradation, emphasizing the critical role of ionic-electronic interactions.
Fluxim’s Paios system was essential for precise capacitance–voltage measurements, allowing accurate extraction of mobile ion and hole concentrations across samples. Paios’ detailed frequency-dependent analysis capabilities provided a strong foundation to validate the complex interplay between ionic and electronic transport, illustrating the advantages of advanced, integrated measurement systems in perovskite research.
The findings are highly relevant, offering new insights into defect engineering strategies for stabilizing tin-based perovskite solar cells and advancing next-generation photovoltaic and optoelectronic technologies.