Zhang Han-Yue, Chen Xiao-Gang, Zhang Zhi-Xu, Song Xian-Jiang, Zhang Tie, Pan Qiang, Zhang Yi, Xiong Ren-Gen
Jiangsu Key Laboratory for Science and Applications of Molecular Ferroelectrics, Southeast University, Nanjing, 211189, P. R. China.
Adv Mater. 2020 Nov;32(47):e2005213. doi: 10.1002/adma.202005213. Epub 2020 Oct 21.
3D ABX organic-inorganic halide perovskite (OIHP) semiconductors like [CH NH ]PbI have received great attention because of their various properties for wide applications. However, although a number of low-dimensional lead-based OIHP ferroelectric semiconductors have been documented, obtaining 3D ABX OIHP ferroelectric semiconductors is challenging. Herein, an A-site cation [CH PH ] (methylphosphonium, MP) is employed to successfully obtain a lead-free 3D ABX OIHP ferroelectric semiconductor MPSnBr , which shows clear above-room-temperature ferroelectricity and a direct bandgap of 2.62 eV. It is emphasized that MPSnBr is a multiaxial molecular ferroelectric with the number of ferroelectric polar axes being as many as 12, which is far more than those of the other OIHP ferroelectric semiconductors and even the classical inorganic perovskite ferroelectric semiconductors BiFeO (4 polar axes) and BaTiO (3 polar axes). MPSnBr is the first MP-based 3D ABX OIHP ferroelectric semiconductor. This finding throws light on the exploration of other excellent 3D ABX OIHP ferroelectric semiconductors with great application prospects.
像[CH₃NH₃]PbI₃这样的3D ABX有机-无机卤化物钙钛矿（OIHP）半导体因其具有多种特性可广泛应用而备受关注。然而，尽管已经报道了许多低维铅基OIHP铁电半导体，但获得3D ABX OIHP铁电半导体仍具有挑战性。在此，采用A位阳离子[CH₃PH₃]⁺（甲基鏻，MP）成功获得了无铅的3D ABX OIHP铁电半导体MPSnBr₃，其表现出明显的高于室温的铁电性以及2.62 eV的直接带隙。需要强调的是，MPSnBr₃是一种多轴分子铁电体，其铁电极轴数量多达12个，这远远超过其他OIHP铁电半导体，甚至超过经典的无机钙钛矿铁电半导体BiFeO₃（4个极轴）和BaTiO₃（3个极轴）。MPSnBr₃是首个基于MP的3D ABX OIHP铁电半导体。这一发现为探索其他具有广阔应用前景的优异3D ABX OIHP铁电半导体提供了线索。
