All-Vacuum-Deposited Perovskite X-ray Detector with a Record-High Self-Powered Sensitivity of 1.2 C Gy^–1 cm^–3

Abstract

Highly sensitive X-ray detection is crucial in, for example, medical imaging and secure inspection. Halide perovskite X-ray detectors are promising candidates for detecting highly energetic radiation. In this report, we describe vacuum-deposited Cs-based perovskite X-ray detectors possessing a p–i–n architecture. Because of the built-in potential of the p–i–n structure, these perovskite X-ray detectors were capable of efficient charge collection and displayed an exceptionally high X-ray sensitivity (1.2 C Gyair –1 cm–3) under self-powered, zero-bias conditions. We ascribe the outstanding X-ray sensitivity of the vacuum-deposited CsPbI2Br devices to their prominent charge carrier mobility. Moreover, these devices functioned with a lowest detection limit of 25.69 nGyair s–1 and possessed excellent stability after exposure to over 3000 times the total dose of a chest X-ray image. For comparison, we also prepared traditional spin-coated CH3NH3-based perovskite devices having a similar device architecture. Their volume sensitivity was only one-fifth of that of the vacuum-deposited CsPbI2Br devices. Thus, all-vacuum deposition appears to be a new strategy for developing perovskite X-ray detectors; with a high practical deposition rate, a balance can be reached between the thickness of the absorbing layer and the fabrication time.

Halide perovskites for sensitive, stable and scalable X-ray detection and imaging

“…Lai reported the preparation of a 1 μm-thick all-inorganic CsPbI 2 Br film with a p–i–n structure using PVD. 49 The film had a surface that was very smooth and mirror-like (Fig. 7(b)), and a LoD of 25.69 nGy air s −1 was achieved.…”

“…32–43 Many mature technologies, including spin coating, blade coating, spray coating, vacuum evaporating drop coating and hot pressing, can be used to prepare perovskite polycrystalline materials. 44–49 Additionally, new methods such as template assisted growth and digital inkjet printing have also been applied to the preparation of perovskite materials. 50 As a result, metal halide perovskites are considered important candidate materials for X-ray detection.…”

“…55 Other methods, like developing blocking layers and 2D–3D junctions, and ferroelectric-assisted X-ray detection, are also demonstrated to be useful strategies. 49,56–64…”

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

“…Besides, loss of materials and operational and maintenance costs will significantly increase production costs compared to other methods. To reduce the production time and costs, Lai et al recently proposed fully thermal-deposited perovskite X-ray detectors (including CsPbI 2 Br, p- and n-type layers), eliminating the need for evacuation between each deposition . But the long deposition time for the perovskite layer remains a challenge.…”

APbI3-A2AgBiI6 Double-Layer Perovskite Film for a Self-Powered and High-Stability X-ray Detector

“…Further, mixed triple-cation perovskite (Cs x MA y FA 1– x – y PbI 3 ) has gained much attention due to its lower trap density and superior phase purity compared to that of MAPbI 3 . − However, when Cs x MA y FA 1– x – y PbI 3 is applied in X-ray detectors, the monovalent ions in perovskite materials are prone to migrate under high bias, which leads to a severe drift of the dark current and photocurrent. In addition, Cs x MA y FA 1– x – y PbI 3 perovskites are susceptible to phase transitions in air environments, accumulating a large number of traps on the perovskite surface, which leads to serious signal current losses …”