Reducing Recombination Processes in the Inverted-Solution-Processed Small-Molecule Solar Cells by the Inserted Fullerene Cathode

Inverted architecture organic solar cells are potentially attractive, due to their long-term stability. However, this type of architecture is poorly applied in small-molecule solar cells, due to lower power conversion efficiencies (PCEs), usually caused by low fill factors. Here, the initially low fill factor of the inverted architecture small-molecule solar cells based on a DPP(TBFu) ₂ :PC ₆₀ BM blend is augmented by the inserted fullerene layer at the cathode, thus resulting in the efficient charge extraction and, up to now, highest PCE for DPP(TBFu) ₂ material and one of the highest for small-molecule DPP derivatives. Highly reproducible devices with PCE up to 5.29% were fabricated, which is notably higher than previously reported results.