Two-Dimensional Layered Perovskite Ferroelectric with Giant Piezoelectric Voltage Coefficient

Piezoelectric sensors that can work under various conditions with superior performance are highly desirable with the arrival of the Internet of Things. For practical applications, a large piezoelectric voltage coefficient g and a high Curie temperature T_c are critical to the performance of piezoelectric sensors. Here, we report a two-dimensional perovskite ferroelectric (4-aminotetrahydropyran)₂PbBr₄ [(ATHP)₂PbBr₄] with a saturated polarization of 5.6 μC cm^-2, high T_c of 503 K [above that of BaTiO₃ (BTO, 393 K)], and extremely large g₃₃ of 660.3 × 10^-3 V m N^-1 [much beyond that of Pb(Zr,Ti)O₃ (PZT) ceramics (20 to 40 × 10^-3 V m N^-1), more than 2 times higher than that of poly(vinylidene fluoride) (PVDF, about 286.7 × 10^-3 V m N^-1)]. Combined with the advantages of molecular ferroelectrics, such as light weight, easy and environmentally friendly processing, and mechanical flexibility, (ATHP)₂PbBr₄ would be a competitive candidate for next-generation smart piezoelectric sensors in flexible devices, soft robotics, and biomedical devices.