Controllable Perovskite Single Crystal Heterojunction for Stable Self‐Powered Photo‐Imaging and X‐Ray Detection

Abstract

Semiconductor heterostructures underpin the design and performance of virtually all modern optoelectronic systems. The clear interface, high crystalline quality, and suitable energy band match lay the foundation for high‐performance heterojunction optoelectronic devices. Here, a facile solution epitaxial growth method is demonstrated for controllably growing CH3NH3PbBr3 single crystal (SC) on the CH3NH3PbCl3 SC, which forms a pn heterojunction with a well‐defined interface and high single‐crystalline quality. The thickness of the epitaxial layer can be finely controlled by adjusting the growth time. Benefiting from excellent built‐in electrical potential at pn heterojunction, the heterojunction detector shows an obvious rectification behavior and high performance in photo‐imaging and X‐ray detection without any power supply, including high responsivity (26.8 mA W−1), fast response time (8/613 µs), and high sensitivity of 868 µC Gyair−1 cm−2 with a record lowest detectable X‐ray dose rate of 15.5 nGyair s−1. Furthermore, it exhibits high‐fidelity UV photo‐imaging capability at zero bias voltage. In addition, the heterojunction detector shows excellent stability by maintaining 99% of the initial responsivity after 120 days without any encapsulation in the atmosphere. This work enables a significant advance in engineering perovskite SC heterojunction for developing novel and functional devices.

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.…”

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

“…5d, under 0.07 μGy air s −1 X-ray irradiation, a signal current ( I signal ) of 0.016 nA was derived by subtracting the average photocurrent ( Ī photo ) by the average dark current ( Ī dark ), that is, I signal = Ī photo − Ī dark . A noise current ( I noise ) as low as 0.0046 nA was obtained by calculating the standard deviation of the photocurrent density using the following expression: 51 where I i is the instant value of photocurrent. A signal-to-noise ratio (SNR) of 3.5 was obtained by I signal / I noise .…”

Perovskite band engineering for high-performance X-ray detection

“…Yan et al [11] fabricated a p-MAPbBr 3 /n-MAPbCl 3 heterojunction photodetector with a sensitivity of 26.8 mA W −1 and a response time of 8 µs. However, organic semiconductor shows low response speed due to its low carriers mobility and high exciton binding energy.…”

“…Hence, by constructing the same dimension perovskite heterojunction, suboptimal carrier transport characteristics caused by defects can be improved. For instance, a lateral grown pn heterojunction of p-type CH 3 NH 3 PbBr 3 (MAPbBr 3 )/n-type CH 3 NH 3 PbCl 3 (MAPbCl 3 ) can effectively passivate surface defects of pristine materials due to excellent and robust lattice matching [11]. Besides, the designed heterojunction endows the existence of built-in electric field and further reduces dark current to perform a favorable carrier transport characteristic, which guarantees for excellent photoelectric performance.…”