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

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(CH2)(3)NH3](2)PbBr4 (BPA(2)-PbBr4, BPA = 3-bromopropylamine), achieves some of superior properties. Interestingly, BPA(2)-PbBr4 reveals a successive relaxor ferroelectric-ferroelectric-paraelectric phase transitions accompanying by a large degree of relaxation delta T-relax = 61 K and ultralow energy loss (tan delta < 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 (3.2302x10(-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.

Automated summary

Inorganic relaxor ferroelectric solid solution single crystals have superior properties that make them suitable for high performance electromechanical devices. However, relaxor ferroelectric single crystals found in organic-inorganic hybrid perovskites are limited, but achieving these properties in them is significant for functional materials design. Fortunately, the first two-dimensional (2D) organic-inorganic hybrid relaxor ferroelectric single crystal, [Br(CH2)(3)NH3](2)PbBr4 (BPA(2)-PbBr4), demonstrates some of these superior properties, including large relaxation temperature change, low energy loss, and strong second harmonic generation effect. It also exhibits temperature-dependent luminescence with adjustable emitted light color, making it compatible with relaxor ferroelectricity.