Liquid-Phase Epitaxial Growth of Large-Area MAPbBr_3–nCl_n/CsPbBr₃ Perovskite Single-Crystal Heterojunction for Enhancing Sensitivity and Stability of X-ray Detector

Abstract

Metal halide perovskites have emerged as next-generation semiconductors for X-ray detection because of their excellent photoelectric properties. However, severe ion migration in three-dimensional (3D) halide perovskites usually causes dark current drift in radiation detectors, especially in high electric fields. Here, we report a liquid-phase epitaxial method based on inverse-temperature crystallization (ITC), with which a hybrid/all-inorganic 3D perovskite single-crystal heterojunction is constructed, using an orientated CsPbBr3 single crystal as a substrate. MAPbBr3– n Cl n /CsPbBr3 single-crystal heterojunctions and single-crystal arrays (through the addition of a mask onto the substrate) with good lattice matching were successfully constructed, laying the foundation for high-performance X-ray detectors. In particular, the MAPbBr3/CsPbBr3 heterojunction drastically enhances the X-ray response of the CsPbBr3 single crystal, with a record-high sensitivity of 2.0 × 105 μC Gyair –1 cm–2 and lowest detection limit of 96 nGyair s–1 for 120 keV hard X-ray detection. Moreover, the dark current drift caused by ion migration is suppressed to 3.92 × 10–4 nA cm–1 s–1 V–1 even in a high reverse electric field of −125 V mm–1. Based on the superior detection performance, it is confirmed that a robust and uniform X-ray imaging detector with good resolution was successfully devised using the heterojunction. Our study provides a simple strategy for constructing perovskite single-crystal heterojunction films and arrays that effectively suppress ion migration that otherwise occurs in 3D halide perovskite single crystals to enable the creation of robust ultrasensitive X-ray detection and imaging systems.

Airflow-Controlled Crystallization for a Multi-Inch 2D Halide Perovskite Single-Crystal Scintillator for Fast High-Resolution X-ray Imaging

“…In the past decade, great progress has been made investigating halide perovskites as direct X-ray detectors − and indirect X-ray detection scintillators. − Currently, indirect-type X-ray detectors based on scintillators are mainstream products for X-ray detection and imaging equipment in the market due to their fast response time and easy integration with the well-known thin film transistor (TFT) and complementary metal oxide semiconductor (CMOS) photodetector arrays. Especially in portable X-ray detection equipment, indirect detectors have more advantages, particularly in cost, over direct X-ray detectors.…”

Perovskite band engineering for high-performance X-ray detection

“…In addition to construct cascade structure, introducing wide gap layer at the interface between perovskite and electrode can generate higher potential barrier, prohibiting the injection of holes or electrons to suppress dark current. Zhou et al [38,39]also reported Cs 0.15 FA 0.85 Pb(I 0.15 Br 0.85 ) 3 /Cs 0.15 FA 0.85 PbI 3 heterojunction adopting dip coating process (Figure 3E). The device can inhibit dark current under X-ray illumination at reversed bias.…”

“…Additionally, except the research about heterojunction based on perovskite such as p-MAPbBr 3 /n-CsPbBr 3 [39], non-perovskite semiconductors can also provide abundant band structure candidates, including CuI [39], Te [40], etc. Although the above researches have been achieved, there still exist massive opportunities for future explore.…”

Improving the Performance and High‐Field Stability of FAPbBr3 Single Crystals in X‐Ray Detection with Chenodeoxycholic Acid Additive

“…[ 6–8 ] 3D organometal perovskite single crystals (SCs) are the rising star due to the high absorption coefficient, [ 9 ] the long carrier diffusion length, [ 10,11 ] the low trap density, [ 12,13 ] and the ease of fabrication. [ 14,15 ] However, the ion migration in perovskite SCs, originating from the nature of ionic crystals and the high tolerance of the perovskite crystal structure, causes the current drift and deteriorate the device stability. [ 16–20 ] Suppressing the ion migration is critical and urgent for the future applications of perovskite single crystals.…”

“…[6][7][8] 3D organometal perovskite single crystals (SCs) are the rising star due to the high absorption coefficient, [9] the long carrier diffusion length, [10,11] the low trap density, [12,13] and the ease of fabrication. [14,15] However, the ion migration in perovskite SCs, originating from the nature of ionic crystals found that Br atoms in MAPbBr 3 migrate easier through vacancies than those in FAPbBr 3 because of the stronger H-bonding between FA ions with Br atoms. Bakr et al [11] observed a carrier diffusion length of 19.0 µm in FAPbBr 3 SCs, indicating the potential excellent capability of carrier collection.…”