Se; [8] Park and co-workers reported sensitivities of CH 3 NH 3 PbI 3 X-ray detectors as high as 11 000 µC Gy air −1 cm −2 . [9] On the other hand, inorganic lead halide perovskites have demonstrated high carrier mobilities, good stability, and low ionic migrations compared to organic-inorganic hybrid perovskite [11] and, therefore, provide higher detection sensitivity toward X-rays; however, they have rarely been studied as X-ray detectors.Another challenge is the fabrication of a thick perovskite film with controlled orientations. A thickness of hundreds of micrometers to millimeters is the prerequisite for complete X-ray attenuation. The uniform orientation of perovskite films is beneficial for charge transport and collection along the electric field direction, thereby requiring a quasi-monocrystalline film. Here, we define a quasi-monocrystalline as the crystal with the same orientation and without grain boundaries along the vertical direction. Current perovskite film-based X-ray detectors face the issue of random orientation and, thus, inefficient charge collection. [9] A new method to fabricate thick quasimonocrystalline perovskite films for X-ray detection is urgently needed.For the first time, here, we employ a hot-pressing method to fabricate thick quasi-monocrystalline inorganic perovskite CsPbBr 3 films. The thickness of the film reaches hundreds of micrometers, which guarantees complete X-ray attenuation. The good orientation of the films is tuned to promote carrier transport close to that of the single-crystal samples. Most importantly, as-fabricated CsPbBr 3 X-ray detectors demonstrate a high sensitivity of 55 684 µC Gy air −1 cm −2 as a result of high carrier mobility, large µτ product, and photoconductive gain effect. Additionally, CsPbBr 3 detectors also exhibit relatively fast response speed, negligible baseline drift, and good stability, which together make the CsPbBr 3 X-ray detector extremely competitive in high-contrast X-ray detection and imaging applications.Currently, the synthesis of high-quality millimeter-thick perovskite films is still a great challenge, because the typical solution-based process often results in many pinholes when the solvent is evaporated out of the film. [9] Here, we propose and demonstrate a hot-pressing method to obtain thick perovskite films. The hot-pressing method avoids the use of any solvent, An X-ray detector with high sensitivity would be able to increase the generated signal and reduce the dose rate; thus, this type of detector is beneficial for applications such as medical imaging and product inspection. The inorganic lead halide perovskite CsPbBr 3 possesses relatively larger density and a higher atomic number in contrast to its hybrid counterpart. Therefore, it is expected to provide high detection sensitivity for X-rays; however, it has rarely been studied as a direct X-ray detector. Here, a hot-pressing method is employed to fabricate thick quasi-monocrystalline CsPbBr 3 films, and a record sensitivity of 55 684 µC Gy air −1 cm −2 is achieved, surpas...

An all-inorganic lead-free halides Cs−Cu−I system, represented by Cs 3 Cu 2 I 5 and CsCu 2 I 3 , has attracted attention for their good photophysical characteristics recently. Successive works had reported their application potential in light-emitting devices. However, there is no report for CsCu 2 I 3 in X-ray scintillation detectors so far. We notice that CsCu 2 I 3 may be advantageous in such an application due to the one-dimensional crystal structure, the congruent-melting feature, and the high spectral matching to some photosensors. In this work, we explore the scintillation properties and imaging application of CsCu 2 I 3 in X-ray scintillator detector. The oriented structure is designed to enhance the imaging performance of a CsCu 2 I 3 detector. Close-space sublimation process and nanoscale seed screening strategy are employed to realize this design by producing a large-area (25 cm 2 ) CsCu 2 I 3 thick film layer with the oriented nanorod structure. This CsCu 2 I 3 detector eventually achieves a high spatial resolution of 7.5 lp mm −1 in X-ray imaging.

Scintillators for radiation detection are of great significance in medical imaging, security, and nondestructive inspection. The current challenge for scintillators is to simultaneously achieve high scintillation light yield, fast radioluminescence, simple film fabrication, large X‐ray attenuation efficiency as well as stable and nontoxic compositions; no previous scintillators fulfill all the above requirements. Here, metal halide Rb2AgBr3, possessing defect‐bound excitonic radioluminescence, is shown as efficient and fast scintillators. This nontoxic and stable scintillator emits from excitons bound to neutral bromine vacancies, enjoying an efficient and spin‐allowed fast emission with minimized self‐absorption. Rb2AgBr3 thus has a high light yield (25 600 photons MeV−1), fast scintillation decay time (5.31 ns), and a record value of light yield versus decay time (4821 photons MeV−1 ns−1). The close‐space sublimation method is developed for fast and scalable fabrication of oriented Rb2AgBr3 films. The scintillator film is further integrated with commercial flat‐panel imagers, and the spatial resolution reaches 10.2 line pairs per millimeter at the modulation transfer function of 0.2, doubling the resolution of conventional CsI:Tl flat‐panel detectors. The dynamic X‐ray imaging and its use to real‐time monitoring of bone movement without ghosting effect is also demonstrated.