Rylene Annulated Subphthalocyanine: A Promising Cone-Shaped Non-Fullerene Acceptor for Organic Solar Cells

The development of various non-fullerene acceptors has further promoted the efficiencies of organic solar cells in the past years. Subphthalocyanine has been recently emerging as an electron acceptor that has unique cone geometry, multiple functionalization, and broad absorption. Here, we designed and synthesized two fully conjugated rylene annulated subpthalocyanines (SubPcPDI3-Cl and SubPcPDI3-OC6H4tBu) bearing different axial substituents. Theoretical calculation revealed a cone-shaped and fully conjugated molecular geometry, and the dihedral angle between perylene diimide (PDI) wings and cone base is ∼25°. Both acceptors showed red-shifted absorbance at ∼680 nm and optical bandgaps of ∼1.70 eV, because of the π-electron conjugation of between the SubPc core and surrounded PDI wings. Thus, the broad absorption, aligned energy levels, and balanced hole/electron mobility ratio endow SubPcPDI3-Cl an excellent power conversion efficiency of 7.53% in non-fullerene solar cells, which presents the highest photovoltaic performance based on subphthalocyanines in solution-processed solar cells.