Triphenyleno[1,2-c:7,8-c']bis([1,2,5]thiadiazole) as a V-Shaped Electron-Deficient Unit to Construct Wide-Bandgap Amorphous Polymers for Efficient Organic Solar Cells.

ABSTRACT

The backbone shape of semiconducting polymers strongly affects their electronic properties and morphologies in films, yet the conventional design principle for building blocks focuses on using linear main chains to maintain high crystallinity. Here, we developed a V-shaped unit, triphenyleno[1,2-c7,8-c']bis([1,2,5]thiadiazole) (TPTz), featuring two 1,2,5-thiadiazole rings fused to a triphenylene core with strong electron-withdrawing properties and an extended conjugation plane. We used TPTz to prepare a highly soluble copolymer, PTPTz-indacenodithiophene (IDT), which exhibited a wide bandgap of 1.94 eV and energy levels suitable for the donor polymer in organic solar cells (OSCs) in combination with non-fullerene acceptors. Despite the amorphous nature of the polymer film, single-junction OSCs with PTPTz-IDTY6 as the active layer achieved a power conversion efficiency of 10.4% (JSC = 19.8 mA cm-2; VOC = 0.80 V; fill factor = 0.66), which is the highest value reported for a single-junction OSC with IDT-based donor polymers. This work demonstrates that TPTz is a promising electron-acceptor unit for developing functional polymers with zigzag structures.