Molecular design of high-performance wide-bandgap acceptor enables versatile organic photovoltaic applications†

As the exploration of organic photovoltaic (OPV) applications deepens, wide-bandgap (WBG) OPV cells exhibit great potential in various novel applications. However, advancements in high-performance WBG acceptors are relatively slow. Herein, we designed and synthesized a WBG acceptor, FPCC-Br, by reducing the overlap of the highest occupied molecular orbital and the lowest unoccupied molecular orbital distributions. Owing to the simplified synthetic route and high synthesis yield, FPCC-based acceptors exhibited the lowest raw material cost among all the WBG acceptors. Benefitting from its excellent charge transfer and exciton dissociation ability, the PBQx-TF:FPCC-Br-based cell exhibited a power conversion efficiency (PCE) of 13.6%, which is the champion efficiency for OPV cells with a bandgap below 720 nm. Furthermore, the PBQx-TF:eC9-2Cl:FPCC-Br-based ternary cell exhibited an impressive PCE of 19.3%. When placed under a light-emitting diode lamp with an illumination of 1000 lux, the PBQx-TF:FPCC-Br-based cells achieved an impressive PCE of 29.3%. Then, the PBQx-TF:FPCC-Br-based cell was employed as the front cell in a tandem cell, realizing a notable PCE of 20.1%. Additionally, these cells connected in series were employed to directly produce hydrogen through underwater photovoltaic electrolysis (UPE), achieving a solar-to-hydrogen efficiency of 6.91%. Moreover, the cells demonstrated remarkable thermal stability at 80 °C, indicating its feasibility for application in UPE. Thus, our work provides a viable molecular design approach for WBG acceptors and underscores the promising prospects of WBG OPV cells for versatile applications.