Organometallic-Based Hybrid Perovskite Piezoelectrics with a Narrow Band Gap

Hybrid organic–inorganic perovskites (HOIPs) with the general formula ABX3 hold phenomenal research interest for their great scientific and technological potential in photovoltaic, piezoelectric, and electroluminescent devices. It is their considerable structural diversity that offers a good opportunity to build a variety of HOIP structures with various functionalities. However, no organometallic-based HOIP piezoelectrics have yet been found, despite the structural diversity and functional richness of organometallic compounds such as the ferrocene-based family. Here, for the first time, we report an organometallic-based HOIP piezoelectric, [(ferro­cenyl­methyl)­tri­methyl­ammonium]­PbI3. Benefitting from the stability of ferrocene-based cations, excellent piezoelectric performance, comparable to that of LiNbO3, can be obtained and optimized by tuning the anionic framework. The involvement of organometallic cations enables a narrow band gap of 2.37 eV, much lower than those of most HOIPs and some inorganic semiconductors. This work provides a new future direction for the study of perovskites and will inspire intriguing research on organometallic-based HOIP piezoelectrics.通式为ABX₃的有机-无机杂化钙钛矿（Hybrid organic–inorganic perovskites, HOIPs）凭借其在光伏、压电及电致发光器件中展现出的巨大科学与技术潜力，引发了学界广泛的研究兴趣。其显著的结构多样性为构建具备多样化功能的各类HOIP结构提供了绝佳契机。然而，尽管二茂铁基家族等有机金属化合物兼具结构多样性与功能丰富性，目前尚未发现基于有机金属的HOIP压电材料。本研究首次报道了一种基于有机金属的HOIP压电材料——[(二茂铁甲基)三甲基铵]PbI₃。得益于二茂铁基阳离子的稳定性，通过调控阴离子骨架可获得并优化媲美铌酸锂（LiNbO₃）的优异压电性能。有机金属阳离子的引入使该材料具备了2.37 eV的窄带隙，其数值远低于多数HOIPs及部分无机半导体的带隙。本研究为钙钛矿的研究开辟了全新发展方向，将推动基于有机金属的HOIP压电材料领域的前沿探索。