ABSTRACT
The strategy of introducing large organic cations into three-dimensional perovskites could reduce the dimensionality of perovskites to form quasi-two-dimensional (quasi-2D) perovskites, resulting in increased stability and reduced detection limits due to less ion migration. Herein, a quasi-2D perovskite single crystal (BDA)(MA)2Pb3Br10 (BDA = NH3C4H8NH3, MA = CH3NH3) with a layered structure was grown by the temperature-cooling solution method. The X-ray detector based on the (BDA)(MA)2Pb3Br10 single crystal has a sensitivity as high as 1984 µC Gy-1 cm-2 at 55.6 V/mm, and it could detect X-rays as low as 28.12 nGy s-1 at 22.2 V/mm. In addition, the X-ray imaging system based on the single-crystal device easily distinguishes between metals and plastics and exhibits a spatial resolution estimated as 250 µm, indicating the feasibility of (BDA)(MA)2Pb3Br10 crystals for X-ray imaging. This research offers a method for the design of quasi-2D layered perovskites and enhances photoelectronic applications in X-ray inspection and imaging.
ABSTRACT
Semiconductor-based X-ray detectors with low detectable thresholds become critical in medical radiography applications. However, their performance is generally limited by intrinsic defects or unresolved issues of materials, and developing a novel scintillation semiconductor for low-dose X-ray detection is a highly urgent objective. Herein, a high-quality rare-earth iodate Tm(IO3 )3 single crystal grown through low-cost solution processing is reported with a wide bandgap of 4.1 eV and a large atomic number of 53.2. The roles of IO and TmO groups for charge transport in the Tm(IO3 )3 are revealed with the structural difference between the [101] and [ 1 ¯ 01 ] $[{\bar{1}}01]$ crystal orientations. Based on anisotropic responses of material properties and detection performances, it is found that the [ 1 ¯ 01 ${\bar{1}}01$ ] orientation, the path with fewer IO groups, achieves a high resistivity of 1.02 × 1011 Ω cm. Consequently, a single-crystal detector exhibits a low dark current and small baseline drifting due to the wide bandgap, high resistivity and less ion migration of Tm(IO3 )3 , resulting in a low detection limit of 85.2 nGyair s-1 . An excellent X-ray imaging performance with a high sensitivity of 4406.6 µC Gyair -1 cm-2 is also shown in the Tm(IO3 )3 device. These findings provide a new material design perspective for high-performance X-ray imaging applications.
ABSTRACT
As emerging materials for capacitor applications, antiferroelectric (AFE) materials possess high energy storage density. AFE single crystals are conducive to studying the physical mechanism of AFE response. However, the preparation of AFE single crystals is a huge and long-standing challenge. Herein, we report the effect of Na/La codoping on the energy storage properties and phase transition of Pb(Lu1/2Nb1/2)O3 (PLN) AFE single crystals. An enhanced recoverable energy storage density of 4.81 J/cm3 with a high energy efficiency of 82.36% is obtained, which is much larger than that of the PbZrO3- and PLN-based AFE crystals. Two superlattice reflections, which stem from the A-site Pb2+ ions and the ordered B-site ions, are identified by X-ray diffraction and selected-area electron diffraction. The domain structures demonstrated a high temperature stability of the AFE phase. A secondary ferroelectric phase transition is induced after codoping, resulting in a sharp improvement of polarization (12.5 µC/cm2), which contributes to the enormous enhancement of energy storage density. This multiphase transition is explained using the modified Ginzburg-Landau-Devonshire phenomenology.
