Ultrasensitive and Robust 120 keV Hard X‐Ray Imaging Detector based on Mixed‐Halide Perovskite CsPbBr_3−nI_n Single Crystals

Abstract

In particular, various X-ray applications with different energies result in different requirements for the detector. For instance, both X-ray diffraction (XRD) and X-ray fluorescence mainly need to detect X-rays with energies lower than 10 keV in scientific research. In contrast, X-rays with energy of 25-50 keV are used to produce images in mammography and chest radiography, [4] while computed tomography (CT) is equipped with digital X-ray image detectors with energy of 80-150 keV. [5,6] Current semiconductor materials such as Si, α-Se, HgI 2 , PbI 2 , and CdZnTe (CZT) are widely applied in direct detectors but suffer from some drawbacks. [7][8][9] Si and α-Se detectors have small attenuation coefficients for light atoms that limit the detection of X-rays to less than 50 keV. HgI 2 and PbI 2 detectors have large leakage currents and poor stability. A commercial CZT detector, which has excellent energy resolution and good photopeak efficiency, is expensive for single crystal (SC) growth and suffers from defects related to charge trapping. [10] Therefore, it is necessary to explore new materials for high-performance radiation detection.In recent years, metal halide perovskites have attracted increasing attention for room-temperature nuclear radiation detection due to their high atomic number (Cs,55, Pb, 82, Br, 35 and I,53), tunable band gap (E g = 1.56-3 eV), [11,12] high resistivity (R = 10 7 -10 12 Ω cm), [13,14] large mobility lifetime product (μτ = 10 −5 to 10 −2 cm 2 V −1 ), [15,16] and low cost in SC growth. These advantageous properties result in large ray attenuation and increased carrier collection efficiency (CCE) for both perovskite SCs and polycrystalline thin films. However, despite their high sensitivity of ≈10 6 -10 8 µC Gy −1 cm −2 , which is two to seven orders of magnitude higher than that of α-Se (20 µC Gy −1 cm −2 ) and CZT (12 000 µC Gy −1 cm −2 ), [17,18] and extremely low detection limit of 0.61 nGy s −1 , which is four orders of magnitude smaller than regular medical diagnostic requirement of 5.5 εGy s −1 , [19] previous studies conducted using these materials have mainly focused on the detection of soft X-rays with energy of several to tens of keV. [18,[20][21][22][23] Few studies have been performed on detecting hard X-rays, specifically in the range greater than 100 keV, which is required in CT imaging and positron emission tomography. In fact, the penetration depthsThe relatively low resistivity and severe ion migration in CsPbBr 3 significantly degrade the performance of X-ray detectors due to their high detection limit and current drift. The electrical properties and X-ray detection performances of CsPbBr 3 −nIn single crystals are investigated by doping the iodine atoms into the melt-grown CsPbBr 3 . The resistivity of CsPbBr 3 −nIn single crystals increases from 3.6 × 10 9 (CsPbBr 3 ) to 2.2 × 10 11 (CsPbBr 2 I) Ω cm, restraining the leak current and decreasing the detection limit of the detector. Additionally, CsPbBr 3 −nIn single crystals exhibit stable dark currents, arising fro...

Dopant-compensated Cs2AgBiBr6−xClx single crystals for photo-imaging and X-ray detection

“…It is worth noting that the trap density decreases as the ratio of doped Cl − increases, which is considered to be a compensating effect of Cl ions. 36,38,44 Differently, only a small fraction of Cl ions contributed to doping compensation, while further doping of Cl ions to 1.55% leads to overcompensation and, in turn, higher trap density. 36,38,44 The above results demonstrate that the Cs 2 AgBiBr 5.933 Cl 0.067 SC has low trap density, which is important for the realization of high-performance photodetectors and X-ray detectors.…”

Hydrogen Bonds Strengthened Metal‐Free Perovskite for Degradable X‐ray Detector with Enhanced Stability, Flexibility and Sensitivity

“…Then, the trap density of MPAZE-NH 4 I 3 • H 2 O also performed with the low trap density of 1.26 × 10 10 cm À 3 through the space charge limited current (SCLC), which is keep up with some MHP-based film of MAPbI 3 (10 11 -10 12 cm À 3 ), FAPbBr 3 (10 9 cm À 3 ) and CsPbBr 3 (10 10 cm À 3 ) (Figure S17b). [5,16,50] Moreover, the response of device to X-ray was performed in Figure 4b, and the key parameter of rise time (t rise ) and fall time (t fall ) is defined as the time for the current rise from 10 % to 90 %, and 90 % to 10 %, respectively. [6,51] The MPAZE-NH 4 I 3 • H 2 O device possesses a quick t rise (6.3 ms) and t fall (9.2 ms).…”

“…The enviable advantages of direct X-ray detectors, including high system integration, simple circuit coupling, and high spatial resolution, have led to their widespread interest in medical inspection, non-destructive testing, and scientific research. [1][2][3][4][5] However, with the development of IoT (Internet of things) and wearable technology, there is an increasing demand for precision medicine and reduction of radiation threat. Yet, traditional rigid devices can hardly meet these demands.…”

“…[15] The materials of higher performance MHP-based X-ray detectors are mostly single crystals or wafer types, whose rigid, small-area, and fragile properties are difficult to be compatible with flexible detection. [5,16] Importantly, the toxic solution and metal ions make it contrary to the concept of bio-friendly, degradable and sustainable wearable electronic devices. [17] Therefore, new requirements for materials are proposed to achieve high-performance flexible X-ray detectors with non-toxic and bio-compatible.…”

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

“…[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.…”