Rylene-imide Incorporated Nonfullerene Electron Acceptors with Enhanced Photovoltaic Performance

In organic solar cells, rylene diimides and rylene imides, exemplified by perylene diimide and naphthalene diimide, are common polymeric and molecular electron-deficient building blocks known for their high electron affinity, high electron mobility, enhanced electrochemical redox stability, and tunable optoelectronic properties. Despite their ubiquity, photovoltaic performance of rylene-imide nonfullerene acceptors (NFAs) has lagged behind fused-ring electron acceptors (FREAs). Recently, we synthesized a new series of FREAs and non-FREAs featuring naphthalene-imide end-capping units in donor-acceptor architectures. These NFAs, bis(naphthalene-imide)arylenelidenes (BNIAs), were found to exhibit enhanced electrochemical redox stability, high carrier mobilities and high photovoltaic performance (>10%) when blended with electron donor polymer PBDB-T. The blends were found to have similar electron mobilities between FREAs and non-FREAs, suggesting the enhanced photovoltaic performance of the FREAs were not due to electron mobilities, but differences in blend morphology and photophysics. These results demonstrate the potentials for rylene imide electron acceptors as a design strategy towards more efficient and electrochemically robust materials for organic solar cells.