Above Room Temperature Ferroelectric Two-Dimensional Halide Double Perovskite with Direction Dependent Properties

Abstract

Herein, we introduce a new non-centrosymmetric 2D halide double perovskite Cl0.26Br3.74PA4AgSbBr8 (CPAS) with A-site linker, 3-chloropropylamine. CPAS exhibits above-room-temperature ferroelectricity, with spontaneous polarization of 3.4 µC.cm-2. The polarization is direction dependent, where ferroelectricity is observed perpendicular to octahedral sheets, and mere capacitive phenomena between sheets. The material shows defect or phonon mediated charge conduction. Optical properties reveal a bandgap of 2.48 eV with blue emission.