Tetraperylenediimide derivative as a fullerene-free acceptor for a high-performance polymer solar cell with the high-power conversion efficiency of 10.32% with open-circuit voltage over 1.0 V

A perylenediimide (PDI) tetramer non-fullerene small molecule acceptor consisting of four PDI units linked to tertraphenylethylene (TPhE) central moiety at their β-positions, denoted as TPhEPDI-4 was designed and synthesized. TPhEPDI-4 was combined with polymeric donor PTB7-Th to fabricate the polymer solar cells. TPhEPDI-4 exhibits an absorption profile ranging from 300 to 630 nm, which is complementary with the PTB7-Th, and the blend PTB7-Th: TPhEPDI-4 exhibits the absorption profile from 300 to 830 nm. The optimized solvent vapor annealed bulk heterojunction-based polymer solar cells showed overall power conversion efficiency of about 10.34% (with a high open-circuit voltage of 1.04 V and voltage loss of 0.53 eV), which is higher than that for the as-cast counterpart (6.12%). The improvement in the power conversion efficiency for solvent vapor annealed active layer-based polymer solar cell is originated from higher and balanced charge carrier mobilities suppressed by bimolecular recombination linked with efficient charge transport. The X-ray diffraction confirms the denser and ordered molecular packing after the solvent vapor annealing as well as crystal coherence length in the PTB7-Th: TPhEPDI-4 film.