Direct X-ray detectors based on metal halide perovskites and their derivatives exhibit high sensitivity and low limit of detection (LoD). Compared with three-dimensional (3D) hybrid lead halide perovskites, low-dimensional A3Bi2I9 perovskite derivatives (A = Cs, Rb, NH4, CH3NH3(MA)) present better stability, greater environmental friendliness, and comparable X-ray detection performance. Here, we report FA3Bi2I9 (FA= CH­(NH2)2) single crystals (SCs) as a new member of the A3Bi2I9 series for X-ray detection, which were prepared by the nucleation-controlled secondary solution constant temperature evaporation (SSCE) method. Centimeter-sized FA3Bi2I9 SCs show a full width at half-maximum (fwhm) of 0.0096°, which is superior to that of recently reported Cs3Bi2I9 (0.058°) and MA3Bi2I9 SCs (0.024°) obtained by inverse temperature crystallization (ITC). The as-grown FA3Bi2I9 SC shows a large resistivity of 7.8 × 1010 Ω cm and a high ion migration activation energy (E a) of 0.56 eV, which can guarantee a low noise level and good operational stability under a large external bias. The FA3Bi2I9 SC detector exhibits a LoD of 0.2 μGyair s–1, a sensitivity of 598.1 μC Gyair –1 cm –2, and an X-ray detection efficiency of 33.5%, which are much better than those of the commercialized amorphous selenium detector. Results presented here will provide a new lead-free perovskite-type material to achieve green, sensitive, and stable X-ray detectors.

Progress towards high performance X-ray detection and dynamic imaging applications, including nondestructive inspection, homeland security, and medical diagnostics, requires scintillators with high light yield, reasonable decay time, low cost, and...

The crystal quality limits the mobility-lifetime (μτ) product and the further applications of perovskite single crystals (PSC) in high energy radiation detections regardless of their high attenuation coefficient. In this paper, high-quality and controllable growth of MAPbX3 PSCs is demonstrated using the liquid-diffusion induced crystallization (LDSC) method. The growth kinetics are modeled to demonstrate the feasibility of the controllable growth via keeping the growth in the mass-transport-limited regime. The crystal growth rate is confirmed theoretically and experimentally to be constant and solely dependent on the growth temperature. A facile method is developed to measure the growth rate without disturbing or suspending the whole process. MAPbBr3 PSC grown at the optimal condition demonstrates a full-width at half-maximum of the (100) X-ray rocking curves of 0.0096°, a fluorescence lifetime of 1099 ns, a trap density of 4.5 × 109 cm–3, and a μτ product of 1.495 × 10–2 cm2 V–1. The resulting MAPbBr3 X-ray detector has a sensitivity of 2181 μC Gyair –1 cm–2. All results indicate that the controllable growth is beneficial to the crystal qualities and device performances. The concept proposed here will be inspiring for the community of researchers of perovskite materials.

Metal halide perovskite and its derivatives show great promise in X-ray detection. However, large-scale fabrication of high-quality thick perovskite films is still full of challenges due to the complicated crystal nucleation process that always introduces lots of cracks or pinholes in the final perovskite film. Here, a MA3Bi2I9 film was fabricated by the cost-effective, scalable spraying process, and MACl was used as an additive to effectively tune the crystallization process. As a result, a dense MA3Bi2I9 film constituted by large grains was obtained, which has a high carrier mobility of ∼1 cm2 V–1 s–1 and a large activation energy (E a ) for ion migration of 0.91 eV. Thanks to the outstanding optoelectronic characteristics, X-ray detectors with a configuration of ITO/MA3Bi2I9/Au show a sensitivity of 35 μC Gyair –1 cm–2 and a limit of detection (LoD) of 0.14 μGyairs–1, which is outstanding compared with commercial α-Se detectors.

Long-life and self-powered betavoltaic batteries are extremely attractive for many fields that require a long-term power supply, such as space exploration, polar exploration, and implantable medical technology. Organic lead halide perovskites are great potential candidate materials for betavoltaic batteries due to the large attenuation coefficient and the long carrier diffusion length, which guarantee the scale match between the penetration depth of β particles and the carrier diffusion length. However, the performance of perovskite betavoltaics is limited by the fabrication process of the thick and high-crystallinity perovskite film.In this work, we demonstrated high-performance perovskite betavoltaic cells using thick, high-quality, and wide-band-gap MAPbBr 3 polycrystalline films. The solvent annealing method was adopted to improve the crystallinity and eliminate the pinholes in the MAPbBr 3 film. The optimal MAPbBr 3 betavoltaic cell achieved a power conversion efficiency (PCE) of 5.35% and a maximum output power of 1.203 μW under radiation of electrons of 15 keV with an equivalent activity of 253 mCi. These results are a nearly 50% improvement from previous reports. Effects of the MAPbBr 3 perovskite layer thickness on the device performance were also discussed. The mechanisms of film-growth processes and device physics could provide insights for the research community of perovskites and betavoltaics.