Zhou Qi-Fang, Pan Lei, Ni Hao-Fei, Ye Lou-Kai, Zhao Yan-Ping, Luo Qing-Ke, Teri Gele, Luo Jia-Qi, Fu Da-Wei, Zhang Zhi-Xu, Shi Chao, Zhang Yi
Institute for Science and Applications of Molecular Ferroelectrics, Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Zhejiang Normal University, Jinhua, 321004, P.R. China.
Chaotic Matter Science Research Center, Jiangxi Province Key Laboratory of Functional Crystalline Materials Chemistry, International Institute for Innovation, Jiangxi University of Science and Technology, Ganzhou, 341000, P.R. China.
Angew Chem Int Ed Engl. 2025 Jul 31:e202509006. doi: 10.1002/anie.202509006.
Hybrid organic-inorganic perovskites (HOIPs) with the ABX formula have garnered significant scientific interest owing to their substantial technological promise in photovoltaics, optoelectronics and ferroelectrics. Their structural diversity and molecular-scale chemical programmability provide an exceptional platform for engineering diverse functional HOIP architectures through targeted compositional design. However, the strategic potential of alkaline earth metals (e.g., Ca, Sr, and Ba) in HOIP assembly remains largely unexplored, with ferroelectric implementations yet to be realized, despite their historical roots in perovskite evolution dating back to the eponymous CaTiO mineral discovered in 1839. Here, for the first time, we report a new family of alkaline earth metal-based HOIP-like ferroelectrics. Benefiting from three-dimensional cage-like structure and multiaxial characteristics, (pyrrolidinium)Ba(ClO) as a representative shows pronounced ferroelectricity with robust polarization switching in both bulk single crystals and compressed polycrystalline powder pellets. Molecular fluorination strategy on pyrrolidinium cation further optimizes the comprehensive ferroelectric properties (R-3-fluoropyrrolidinium)Ba(ClO), enhancing Curie temperature, increasing polar axes and doubling polarization values. Combined with their easy preparation and good plasticity, this discovery provides a brand-new structural paradigm for HOIP ferroelectrics and highlights exceptional promise in emerging flexible ferroelectric applications.
具有ABX化学式的有机-无机杂化钙钛矿（HOIPs）因其在光伏、光电子和铁电领域的巨大技术潜力而引起了科学界的广泛关注。它们的结构多样性和分子尺度的化学可编程性为通过有针对性的成分设计来构建各种功能性HOIP结构提供了一个独特的平台。然而，尽管碱土金属（如钙、锶和钡）在钙钛矿的发展历史中有着根源，可追溯到1839年发现的同名矿物CaTiO，但它们在HOIP组装中的战略潜力在很大程度上仍未被探索，铁电应用也尚未实现。在此，我们首次报道了一类新型的基于碱土金属的类HOIP铁电体。得益于三维笼状结构和多轴特性，作为代表性的（吡咯烷鎓）Ba(ClO)在块状单晶和压缩多晶粉末颗粒中均表现出显著的铁电性和强大的极化切换。对吡咯烷鎓阳离子的分子氟化策略进一步优化了（R-3-氟吡咯烷鎓）Ba(ClO)的综合铁电性能，提高了居里温度，增加了极轴并使极化值翻倍。结合其易于制备和良好的可塑性，这一发现为HOIP铁电体提供了一种全新的结构范式，并突出了其在新兴柔性铁电应用中的巨大潜力。
