Fluorinated pyrazine-based D–A conjugated polymers for efficient non-fullerene polymer solar cells†
Over the past decade, fluorinated materials have become the dominant donors for achieving high power conversion efficiencies in organic solar cells (OSCs). Research on F substituents on N-heterocycle-based polymer solar cells was firstly carried out by introduction of the F atom into the pyrazine-based acceptor unit, which was successfully applied in constructing a polymer (BDT-FPY) for PSCs. MeIC-based polymer solar cells (PSCs) with BDT-FPY as a donor achieve a high power conversion efficiency (PCE) of up to 12.30%, significantly higher than that of a device based on BDT-PY:MeIC (the PCE of unfluorinated polymer donor BDT-PY is 10.2%). The higher PCE of BDT-FPY:MeIC is attributed to more balanced μh/μe, better molecular packing, and more appropriate phase separation features. This result shows great potential for creating high-performance N-heterocycle-based PSCs.