Solution-Grown Perovskite Single Crystalline Radiovoltaic Cells with 10% Power Conversion Efficiency

Nuclear batteries present an appealing energy source characterized by an exceptionally long operational lifespan and a remarkable energy density, finding prominent application for equipment requiring sustained, autonomous operation over protracted durations, encompassing spacecraft, cardiac pacemakers, subaqueous systems and automated scientific stations. Except of radiation safety issues, primary constraint hindering the extensive adoption of nuclear batteries is attributed to the limited efficiency and intricate fabrication processes of energy-conversion materials. Most widespread nuclear batteries are radioisotope thermoelectric generators which exhibit an energy conversion efficiency of merely 5%. In the quest for augmented efficiency, research endeavors have shifted towards direct conversion of gamma and beta radiation through radiovoltaic cells, where the best efficiency is so far achieved with costly and non-scalable diamond battery technology. In this study, we address the issue of efficiency, reporting 10% power conversion efficiency for the direct conversion of high-energy photons up to 20 keV with solution-grown methylamonium-formamidinium lead iodide (MAFAPbI₃) perovskite single-crystal radiovoltaic cells. Our experimental investigation determined the electron-hole pair creation energy for MAFAPbI₃ single crystals to be 5.05 eV, substantiating that the short-circuit current closely approaches the theoretical upper limit, as defined by the Klein model. Additionally, the devices exhibited a high open-circuit voltage of 600 mV even under low irradiation power density conditions of 69 nW mm^-2. Furthermore, the perovskite radiovoltaic cells demonstrated remarkable stability, maintaining their performance for a continuous 24-hour X-ray irradiation at a power density of 100 nW mm^-2. These findings underscore the promising potential of highly efficient and low-cost perovskite-based nuclear batteries.