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 (DJP_n=2, AMP = 4-(aminomethyl)piperidinium; MA = methylammonium), which shows an out-of-plane polarization and a saturated polarization (P_s) value of 3.7 μC/cm². The coercive field of DJP_n=2 (0.34 kV/cm) is lower than that for the n = 1 homologue (AMP)PbI₄ (DJP_n=1,0.4 kV/cm). DJP_n=2 has a much longer carrier lifetime and absorption edge (580 nm, 2.13 eV) in comparison to DJP_n=1 (523 nm, 2.37 eV); thus, DJP_n=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.