Self-Powered Photodetector Using Two-Dimensional Ferroelectric Dion–Jacobson Hybrid Perovskites

Dion–Jacobson (DJ) phase organic–inorganic hybrid perovskites (OIHPs) have emerged as promising alternatives to Ruddlesden–Poppers perovskites because of their chemical stability and ferroelectric phase. Here we fabricate a ferroelectricity-modulated photodetector based on the n = 2 homologue of the ferroelectric two-dimensional DJ-OIHP (AMP)­(MA)­Pb2I7 (DJPn=2, AMP = 4-(aminomethyl)­piperidinium; MA = methylammonium), which shows an out-of-plane polarization and a saturated polarization (Ps) value of 3.7 μC/cm2. The coercive field of DJPn=2 (0.34 kV/cm) is lower than that for the n = 1 homologue (AMP)­PbI4 (DJPn=1,0.4 kV/cm). DJPn=2 has a much longer carrier lifetime and absorption edge (580 nm, 2.13 eV) in comparison to DJPn=1 (523 nm, 2.37 eV); thus, DJPn=2 can be used for efficient photodetection in the visible range, in which a responsivity of 0.16 mA/W was achieved at 532 nm. The influence of remnant polarization on the direction and magnitude of the photocurrent was also demonstrated.戴森-雅各布森（Dion–Jacobson，DJ）相有机-无机杂化钙钛矿（Organic-Inorganic Hybrid Perovskites, OIHPs）因兼具化学稳定性与铁电相特性，已成为鲁德尔斯登-波珀斯（Ruddlesden–Poppers）钙钛矿的极具潜力的替代材料。本研究基于铁电二维DJ-OIHP的n=2同系物(AMP)(MA)Pb2I7（DJPn=2，其中AMP为4-(氨基甲基)哌啶鎓，MA为甲胺鎓）制备了铁电调制型光电探测器。该材料表现出面外极化特性，饱和极化强度（Ps）达3.7 μC/cm²。DJPn=2的矫顽场（0.34 kV/cm）低于n=1同系物(AMP)PbI4（DJPn=1，0.4 kV/cm）。相较于DJPn=1（吸收边523 nm，对应带隙2.37 eV），DJPn=2拥有更长的载流子寿命与更红移的吸收边（580 nm，对应带隙2.13 eV）；因此DJPn=2可用于可见光波段的高效光电探测，在532 nm波长下实现了0.16 mA/W的光电响应度。本研究还证实了剩余极化对光电流方向与幅值的调控作用。