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.
Methylammonium lead halide perovskite (MAPbX 3 ) has been a great candidate for photovoltaic applications. However, dissociation of the methylammonium unit has been observed, producing a CH 3 – group binding to MAPbX 3 and a free NH 3 molecule. To date, there is no clear evidence on the specific binding site of CH 3 –. In this study, MAPbBr 3 thin films are prepared with deliberately added trimethyl lead bromide, (CH 3 ) 3 PbBr. X-ray photoelectron spectroscopy is applied to comparatively investigate the electronic structure of MAPbBr 3 films with and without (CH 3 ) 3 PbBr modification. CH 3 -Pb species are identified, confirming that Pb is a binding site for CH 3 produced upon MA dissociation. Graphical abstract
Youchao Kong,Pinsen Zhang,Donghua Fan,Xiaoshuang Li,Shanshan Yan
Assembling perovskites into heterojunctions enables multifunctional high-performance photodetectors. Compared with vertical heterojunctions, lateral heterojunctions enhance the optoelectronic performance of devices due to the direct contact between the photosensitive layer and light, reducing light reflection losses. However, the fabrication of all-perovskite lateral heterojunctions is challenging through a solution method. The first perovskites formed are easily dissolved by the solvent of the second precursor, hindering their further application in photodetectors. In this study, we have developed a preparation process for the lateral microwire (MW)/film heterojunction and the Ag/RbCu2I3 MW/MAPbBr3 film/indium tin oxide heterojunction photodetector by utilizing an optical fiber-based physical transfer step. Thanks to the high-quality RbCu2I3 MW/MAPbBr3 film lateral heterojunction, the device demonstrated excellent optoelectronic performance at 0 V bias voltage, with a responsivity of 0.79 mA·W–1 and a detectivity of 5.34 × 1012 Jones under 339 nm radiation. In addition, the device exhibited consistent and rapid response times under 355 and 450 nm irradiation. This optical fiber-based physical transfer method provides a self-powered light detection strategy for the preparation of all-perovskite lateral heterojunctions.
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