Unfused Nonfullerene Acceptors Based on Simple Dipolar Merocyanines

Merocyanine (MC) dyes exhibit facile synthesis and attractive optical properties, making them widely studied as the donor materials in organic solar cells (OSCs). In this study, for the first time, simple indole-based MCs are successfully designed as unfused nonfullerene acceptors (NFAs) for OSCs by forming dimers with A-D-pi-D-A structure, which possess enhanced photostability compared to the well-known ITIC acceptor and high electron mobility in blend films. When blended with P3HT donor, one of the dimers, i. e. Z2, shows a good cell efficiency of 3.53 %, which outperforms the performance of most of P3HT/NFA blends, particularly for unfused systems, and thus indicates good potential of simple MCs as NFAs.