Organic interlayer materials for non-fullerene solar cells

Organic solar cells (OSCs) based on non-fullerene acceptors have recently achieved high power conversion efficiencies over 19%, thus rapidly advancing third-generation photovoltaic technologies. Solution-processable organic interlayers, positioned between organic photoactive layers and metal electrodes, are essential to furnish optimal OSCs because of their pivotal role in adjusting work functions of metal electrodes, enhancing build-in potential of the devices and alleviating charge recombination loss. This review summarizes recent progresses in organic materials used as multiple functional cathode and anode interlayers towards efficient and stable non-fullerene OSCs. We concentrate on representative interlayer materials associated with their structure–performance relationship, aiming to provide effectual designing guidelines and propose potential opportunities and directions in this field.