Discovery of a 2D Hybrid Silver/Antimony‐Based Iodide Double Perovskite Photoferroelectric with Photostrictive Effect and Efficient X‐Ray Response

TLDR: In this article , a 2D iodide double perovskite photoferroelectric is reported based on Ag/Sb ions, which possesses a high Curie temperature of 414 K (above BaTiO3), large spontaneous polarization of 9.6 μC cm−2, ferroelectric photovoltaic effect, and photostrictive effect.

Abstract: 2D hybrid halide double perovskites (HHDPs) have been demonstrated to be a promising alternative to conventional lead‐based halide perovskites as a new system of photoferroelectrics, due to their unique characteristics of environmental friendliness, favorable stability, and fascinating optoelectronic properties. Herein, for the first time, a 2D iodide double perovskite photoferroelectric is reported based on Ag/Sb ions, (4,4‐DFPD)4AgSbI8 (4,4‐DFPD = 4,4‐difluoropiperidinium), which possesses a high Curie temperature of 414 K (above BaTiO3), a large spontaneous polarization of 9.6 μC cm−2, ferroelectric photovoltaic effect, and photostrictive effect. Notably, to the best of the authors’ knowledge, the discovery of photostriction in HHDP photoferroelectrics is unprecedented. Moreover, (4,4‐DFPD)4AgSbI8 exhibits an impressive X‐ray responsivity, with a sensitivity as high as 704.8 μC Gyair−1 cm−2 at 100 V bias and a detection limit as low as 0.36 μGyair s−1 at 10 V bias, both of which outperform the current all HHDP photoferroelectrics. This work enriches the photoferroelectric family, and proves that Ag/Sb‐based HHDP photoferroelectrics are a promising candidate for the next‐generation optoelectronic devices.