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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 MAPbBr3 polycrystalline films. The solvent annealing method was adopted to improve the crystallinity and eliminate the pinholes in the MAPbBr3 film. The optimal MAPbBr3 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 MAPbBr3 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.

Fabricating perovskite single-crystal thin films (SCTFs) in controllable manner is the major challenge for the promising potential applications in optoelectronic devices. Although modifying the sub...

Halide perovskite single crystal thin films (SCTFs) have attracted extraordinary attentions due to the promising potential applications as the high-performance optoelectronic devices. However, fabricating the high-quality and large-area perovskite SCTFs is still the main challenge for the future commercialization. In this work, systematical investigations show that the evaporation of methylamine can lead to the precipitation of the PbBr2 phase, which is one of the major causes of the poor crystallinity and the surface morphology. A simple strategy is demonstrated to improve the crystallinity and properties of MAPbBr3 SCTFs using the mainstream space-confined method, by controlling the evaporation of the methylamine during the crystal growth, i.e. the growth temperature and the PbBr2/MABr molar ratio in precursor. The crystal quality of MAPbBr3 SCTFs can be improved by lowering the growth temperature and decreasing the PbBr2/MABr molar ratio in the precursor. The best MAPbBr3 SCTF is obtained at 50 °C with the PbBr2/MABr molar ratio of 0.85 in precursor solution. The SCTF is in square shape (~2 mm × 2 mm) and with a full width of half-maximum of the rocking curve of (100) crystal plane of 0.051o. These results will inspire the further explorations in fabricating the high-quality perovskite SCTFs.

Halide perovskite single-crystal films have attracted significant attention due to their extraordinary performance in various optoelectronic applications such as solar cells, light-emitting devices, photodetectors, and X-ray detectors. However, the surface quality and crystallinity of perovskite single crystal films (PSCFs) prepared by the popular space-confined method limits the applications in the high-performance devices. Herein, we demonstrate a simple method to improve the crystallinity of MAPbBr3 PSCFs by introducing dimethylsulfoxide (DMSO) as the coordination solvent into the precursor solutions. When increasing the DMSO concentration in the perovskite precursor solutions, the precipitation of lead bromide on the surface of PSCFs is suppressed. The best MAPbBr3 PSCF obtained at 2.5% DMSO concentration has a full width at half maximum (FWHM) of 0.0042° in the X-ray rocking curve measurements, which is significantly improved compared with the best published results. The mechanism how DMSO concentration affect the crystallization process and the formation of defects is also discussed. The study provides an effective route to fabricate perovskite single crystal films and inspires further explorations on the production of high-performance optoelectronic devices.