Direction Dependent Ferroelectricity and Conductivity in a Single Crystal 2D Halide Double Perovskite

Halide ferroelectric materials have garnered a lot of interest because of their distinctive electrical and structural characteristics. In this study, the design and development of a new non-centrosymmetric 2D layered halide double perovskite material, Cl1.14Br2.86PA4AgInBr8 (CPAIn) is reported. This material shows ferroelectric properties above room temperature, with a Curie temperature of 190 degrees C. This behavior is achieved through the substitution of the halogenated A-site organic linker, 3-chloropropylammonium. CPAIn exhibits anisotropic ferroelectric behavior with higher spontaneous polarization of 6.25 mu C cm-2 along the perpendicular direction to the octahedral layers, whereas the value decreases to 0.174 mu C cm-2 between sheets. While using bottom contact to study the nature of polarity within a sheet, the P-E loop displays capacitive loop. The nature and value of polarization is highly direction dependent, and to further understand the mechanism of conduction, a combination of temperature-dependent impedance studies and poling dependent conductivity techniques are employed. These directional dependent properties hold immense potential in memory devices, sensors and photovoltaics, piezoelectric devices and energy storage. This work reports on a new non-centrosymmetric 2D halide perovskite material synthesized using a halogenated organic linker. This material exhibits above room temperature ferroelectricity with anisotropic ferroelectric properties. The direction dependent polarization, conductivity and the mechanism of charge transport are investigated. image