Slot-die printed non-fullerene organic solar cells with the highest efficiency of 12.9% for low-cost PV-driven water splitting

Solution processed organic solar cells (OSCs), as one promising solar energy conversion technology, have attracted much attention for their potential use in photovoltaic market, but their promise in the economic conversion of solar energy into chemical energy (solar fuels) has only recently been recognized. In this study, we apply a non-fullerene system (PBDB-T-SF:IT-4F) for closing the efficiency gap between lab-produced OSCs and large-scale printed modules via a slot-die coating system. By finely balancing the flowing rate and coating speed combination as a printing strategy, we obtain high-quality printed blend microstructure. The printed solar cells not only exhibit a power conversion efficiency (PCE) of 12.90%, which is comparable to that of state-of-the-art devices fabricated by spin coating and doctor-blading, but also present the impressive photovoltaic performance with the PCE of over 12% in the flexible devices and the modules with two cells connected in series. Coupling a large-scale printed module to an existing water splitting system would yield a solar-to-hydrogen (STH) efficiency of 6.15%. Furthermore, design principles for combining solar cells, electrolysis cell and new catalysts are provided for minimizing their power loss during the conversion of electrical energy into fuel.