Fine-tuning of film morphology through addition of a third component enables organic solar cells with efficiency over 18%†

Ternary organic solar cells (OSCs) hold great promise for enhancing device performance. In this study, Y-TNF, which shares a similar structure with Y6 and exhibits good compatibility with PM6 and Y6, was introduced as the third component into the PM6 : Y6 system. The resulting ternary photovoltaic device achieves a power conversion efficiency (PCE) exceeding 18%. Further analysis reveals that the addition of Y-TNF facilitates the formation of an optimal nanofiber network structure and a highly ordered molecular arrangement within the active layer. Compared to the binary PM6 : Y6 system, the ternary PM6 : Y6 : Y-TNF system demonstrates improved carrier mobility, higher exciton dissociation efficiency, and enhanced charge collection efficiency, thus, leading to effectively suppressing trap-assisted and bimolecular charge recombination. These findings demonstrate that the incorporation of a structurally analogous third component can significantly enhance device efficiency of the OSCs, offering valuable insights and confidence for further performance enhancements in the future.