The first 2D organic-inorganic hybrid relaxor-ferroelectric single crystal

Abstract

Inorganic relaxor ferroelectric solid solution single crystals are spurring new generations of high performance electromechanical devices, including transducers, sensors, and actuators, due to their ultrahigh electric field induced strain, large piezoelectric constant, high electromechanical coupling factor and low dielectric loss. However, relaxor ferroelectric single crystals found in organic-inorganic hybrid perovskites are very limited, but achieving these superior properties in them will be of great significance in the design of modern functional materials. Fortunately, here the first two-dimensional(2D) organic-inorganic hybrid relaxor ferroelectric single crystal, [Br(CH_2)_3NH_3]_2PbBr_4(BPA_2-PbBr_4, BPA = 3-bromopropylamine), achieves some of superior properties. Interestingly, BPA_2-PbBr_4 reveals a successive relaxor ferroelectric-ferroelectric-paraelectric phase transitions accompanying by a large degree of relaxation ΔTrelax= 61 K and ultralow energy loss(tanδ<0.001). Meanwhile, it exhibits a superior second harmonic generation(SHG) effect with maximum value accounts for 95% of the standard KDP due to great deformation of structure(3.2302×10~(-4)). In addition, temperature dependent luminescence spectra(80–415 K) exhibit fluorescence and phosphorescence overlapping emission originated from inorganic and organic components with the nanosecond-scale short lifetime and the millisecond-scale long lifetime, respectively, and the color of the emitted light is continuously adjustable,which is the first to achieve luminescence and relaxor ferroelectricity compatibility.