Hetero-tandem organic solar cells drive water electrolysis with a solar-to-hydrogen conversion efficiency up to 10%

A hetero-tandem organic photovoltaic (OPV) device consisting of large (PM6:IT-M) and small-bandgap (PM6:Y6) bulk-heterojunctions is developed to provide an open-circuit voltage of 1.84 V and a power-conversion-efficiency of 11.7%, which could serve as an ideal light absorber to drive water electrolysis. The fabricated OPV is combined with an electrolyzer composed of NiFeOx(OH)y and Pt electrocatalysts to demonstrate a photovoltaic electrolysis (PV-EC) system. Furthermore, the system is designed to locate the operating voltage of the OPVEC system at the maximum power point of OPV to minimize power loss. As a result, our hetero-tandem OPVEC device achieves the highest solar-to-hydrogen conversion efficiency among OPV-based systems, (up to 10%), which represents a new benchmark for OPV-based solar fuel production. Finally, a wireless monolithic organic artificial leaf is constructed for the first time, which demonstrates a stable solar hydrogen production in water.