Helical π‐Extended Terrylene Diimide Dimer Based on Ring‐Fused Ethylene Bridge for Organic Solar Cells

Abstract Terrylene diimides (TDIs), as the higher homologues of perylene diimide (PDI) in the series of rylene diimides (RDIs), exhibit several especial properties including enhanced absorption ability in the near infrared (NIR) region, higher fluorescence quantum yields as well as stronger π–π stacking in comparison to naphthalene diimides (NDIs) and perylene diimides (PDIs). However, TDIs have been largely overlooked in terms of their photovoltaic applications because of the chemical inaccessibility and poor solubility. In this contribution, a helical π‐extended terrylene diimide dimer based on ring‐fused ethylene bridge, namely FTDI2 is designed and synthesized. The photovoltaic performances of FTDI2 and the parent TDI are investigated using the commercially available PTB7‐Th as the electron donor. A significantly improved power‐conversion efficiency (PCE) of 5.11 % compared to that of TDI based ones (0.5 %) is achieved for FTDI2 ‐based device, demonstrating the potential of terrylene dyes in the photovoltaics field.