Ultralow Detection Limit and Robust Hard X-ray Imaging Detector Based on Inch-Sized Lead-Free Perovskite Cs₃Bi₂Br₉ Single Crystals

Abstract

Halide perovskites are promising candidates for soft X-ray detection (<80 keV) owing to their high X-ray absorption coefficient, resistivity, and mobility lifetime product. However, the lack of large high-quality single crystals (SCs) renders it challenging to manufacture robust hard X-ray imaging systems (>100 keV) with a low detection limit and stable dark current. Herein, high-quality inch-size two-dimensional (2D) Cs 3 Bi 2 Br 9 (CBB) single crystals are grown from a melt via the Bridgman method. The crystal quality is enhanced by eliminating inclusions of CsBr-rich phases and restraining the trap-state density, leading to an enhanced resistivity of 1.41 × 10 12 Ω cm and a mobility lifetime product of 8.32 × 10 −4 cm 2 V −1 . The Au/CBB/Au singlecrystal device exhibits a high sensitivity of 1705 μC Gy air −1 cm −2 in all-inorganic bismuth-based perovskites and an ultralow detection limit of 0.58 nGy air s −1 in all of the bismuth-based perovskites for 120 keV hard X-ray detection. The CBB detector exhibits high work stability with an ultralow dark current drift of 2.8 × 10 −10 nA cm −1 s −1 V −1 and long-term air environment reliability under a high electric field of 10 000 V cm −1 owing to the ultrahigh ionic activation energy of the 2D structure. The proposed robust imaging system based on CBB SC is a promising tool for X-ray medical imaging and diagnostics. KEYWORDS: lead-free perovskites, two-dimensional perovskites, Cs 3 Bi 2 Br 9 single crystal, ultralow detection limit, X-ray imaging

Metal‐Free PAZE‐NH4X3⋅H2O Perovskite for Flexible Transparent X‐ray Detection and Imaging

“…Then, the different intensity of current signals at each pixel was collected, and outlined the specific characteristics of the object [54, 55] . The 3×3 pixelated X‐ray imager exhibits uniform photocurrent and dark current (Figure 5b), which ensures the quality of imaging figures [56, 57] . Subsequently, the advancement of the flexible detector was shown by placing curving “L”, “Z” and “U”‐shaped copper plates on the bent and flat imager.…”

“…[54,55] The 3 × 3 pixelated X-ray imager exhibits uniform photocurrent and dark current (Figure 5b), which ensures the quality of imaging figures. [56,57] Subsequently, the advancement of the flexible detector was shown by placing curving "L", "Z" and "U"shaped copper plates on the bent and flat imager. According to the gradient photocurrent difference of each pixel, the rigid devices present more or less distortion for the nonuniform spatial distribution of X-ray dose, which is highlighted in Figure 5c.…”

Scalable Fabrication of Metal Halide Perovskites for Direct X-ray Flat-Panel Detectors: A Perspective

“…35 Since conventional 3D perovskites like MAPbI 3 suffer from ion migration and degradation, 83 we believe that exploring scalable fabrication of low dimensional perovskites is needed for the realization of Pe-FPD. 21,23,74,75 Inferior charge transport properties in low dimensional perovskites can be addressed by composite structures, such as 2D−3D mixed perovskites. 39 In terms of the fabrication method, it should be able to make a wide family of perovskite materials, which is preferable.…”

“…Many perovskite compositions are being tested for X-ray detection applications . Since conventional 3D perovskites like MAPbI 3 suffer from ion migration and degradation, we believe that exploring scalable fabrication of low dimensional perovskites is needed for the realization of Pe-FPD. ,,, Inferior charge transport properties in low dimensional perovskites can be addressed by composite structures, such as 2D–3D mixed perovskites …”

“…Recently, metal halide perovskites − and their analogues, such as low-dimensional perovskites − and double perovskites, − have emerged as promising photoconductive layers (Figure ) thanks to their high X-ray attenuation coefficient, high mobility, and long lifetime of charge carriers. Several review papers have summarized the progress of perovskite-based X-ray detectors. − Perovskite X-ray detectors have shown more than 100 times higher sensitivity and less than 100 times lower detection limit than conventional a-Se-based X-ray detectors.…”