Highly Efficient and Stable Organic Photovoltaic Cells for Underwater Applications

Abstract Organic photovoltaic (OPV) technology holds tremendous promise as a sustainable power source for underwater off‐grid systems. However, research on underwater OPV cells is relatively scarce. Here, this gap is addressed by focusing on the exploration and development of OPV cells specifically designed for underwater applications. An acceptor, named ITO‐4Cl, with excellent water resistance, is rationally designed and synthesized. Benefiting from its low energetic disorder and an absorption spectrum well‐suited to the underwater environment, the ITO‐4Cl‐based OPV cell achieves an unprecedented power conversion efficiency (PCE) of over 25.6% at a water depth of 1 m. Additionally, under 660 nm laser irradiation, the cell demonstrates a notable PCE of 31.6%, indicating its potential for underwater wireless energy transfer. Due to the mitigation of thermal effects from solar irradiation, the lifetime of the ITO‐4Cl‐based OPV cell exceeds 7000 h. Additionally, a flexible OPV cell is fabricated that maintains its initial PCE even under exposure to high pressures of 5 MPa. A 32.5 cm 2 flexible module achieves an excellent PCE of 17%. This work fosters a deeper understanding of underwater OPV cells and highlights the promising prospects of OPV cells for underwater applications.