Interfacial ferroelectricity unlocks stable formamidinium-based perovskites
Yong Wang, Wenbin Han, Xingtao Wang, Biao Li, Yehui Wen, Tianchi Zhang, Miao Kan, Dongming Zhao, Yu Wang, Weihua Ning, Xuegong Yu, Deren Yang
Abstract
Pure iodide formamidinium (FA) based-perovskite has emerged as highly promising candidates for perovskite photovoltaics, but it remains challenging to achieve long-term phase-stabilized FA-based perovskites. Herein, we present a physics-driven strategy of interfacial ferroelectricity, achieved by the integration of ferroelectric CsMnBr3 nanocrystals (NCs) into FA-based perovskites. The ferroelectric field generated by these NCs promotes FA+ cation ordering, modulates Pb–I framework, and enhances the structural regulation of the perovskite lattice. This synergistically increases the kinetic barrier for the undesired Pb-I octahedral transformation and raises the energy barrier for ion migration. The resulting perovskite materials exhibit high structure stability, enabling perovskite solar cell (PSC) minimodule to retain 99% of its initial efficiency after 1000 hours’ stability testing under 85% relative humidity at 85 °C. Owing to the improvement at the interface, the PSCs yield an efficiency of 26.62% (certified 26.40%), and the minimodules reach 24.67% (certified 23.23%). This work presents an effective approach to achieving high-performance, long-term stable perovskite optoelectronic devices through interfacial ferroelectric engineering. Achieving long-term phase-stabilized formamidinium (FA)-based perovskites remains challenging. Here, authors integrate ferroelectric CsMnBr3 nanocrystals into FA-based perovskites for ferroelectric field-mediated structural regulation, achieving maximum efficiency of 26.62% for stable solar cells.