Beneath the surface: investigating Perovskite solar cells under water

Beyond traditional rooftop and building-integrated photovoltaics (BIPV), photovoltaic (PV) devices find applications in agrivoltaics, space, and indoor settings. However, the underwater (UW) environment remains largely unexplored. Below 50 m, the solar spectrum shifts dramatically, with only blue-green light (400–600 nm) available. Perovskite solar cells (PSCs), known for their high-power conversion efficiencies (PCEs) and tunable bandgaps, offer potential for this environment. Initially, simulations compared the intensity of the solar radiation based on three models, each based on a different water body, down to a depth of 10 m. The trend of maximum theoretical performance, ranging from 1.5 to 3 eV band gap, was analyzed with respect to depth. In this pioneering study, a wide bandgap PSC, based on FaPbBr3, has been selected to operate underwater. Results were achieved through a complete in-house process encompassing fabrication, encapsulation, and underwater measurement. A 10-day saltwater submersion test of a damaged device confirmed minimal lead release, meeting stringent legal standards for lead in potable water. PV performance was evaluated UW, demonstrating an enhanced conversion efficiency within the first centimeters of water. This enhancement is due to water's optical and cooling properties. This work opens new frontiers for exploration, both for perovskites, traditionally considered unsuitable for humid environments, and for the increasingly human-occupied underwater realm, which is seeing the development of activities such as wine aging and plant cultivation.