Monolithically integrated, photo-rechargeable portable power sources based on miniaturized Si solar cells and printed solid-state lithium-ion batteries

The combination of energy generation and energy storage systems is the ultimate solution to meet the ever-increasing demand for high-energy-density power sources. Here, we demonstrate a new class of monolithically integrated, photo-rechargeable portable power sources based on miniaturized crystalline Si photovoltaics (c-Si PVs) and printed solid-state lithium-ion batteries (LIBs). A solid-state LIB with a bipolar cell configuration is fabricated directly on the aluminium electrode of a c-Si PV module through an in-series printing process, which enables the seamless architectural/electrical connection of the two different energy systems. The single-unit PV-LIB device shows exceptional electrochemical performance that lies far beyond those achievable by conventional PVs or LIBs alone: it displays fast, low-light-intensity and high-temperature photo-charging; a photo-electric conversion/storage efficiency of 7.61%; a sustainable cycling performance; and continuous discharging at an extremely high current density of 28C under sunlight illumination. This study opens a facile and scalable route for the development of single-unit, photo-rechargeable mobile high-performance batteries that are required for the future era of ubiquitous electronics.