Unfused vs fused thienoazacoronene-cored perylene diimide oligomer based acceptors for non-fullerene organic solar cells

Abstract

Ring-fusion is a feasible design strategy to improve the photovoltaic performance of perylene diimide (PDI) based non-fullerene acceptors (NFAs) in which multiple PDI units are linked at the bay position to an aromatic central core. Research on the effect of ring-fusion in the case of large π-conjugation cores is rarely investigated. In this contribution, the planar thienoazacoronene (TAC) was used as the central core, equipping with two ethylene bridged helical PDI dimer (PDI2), to afford the non-fused (TAC-diPDI2) and fused (FTAC-diPDI2) NFAs. The photovoltaic performances of these two NFAs were explored using PBDB-T as the electron donor. The non-fused TAC-diPDI2 based organic solar cells (OSCs) exhibits higher power conversion efficiency (PCE) of 6.59% than that of ring-fused FTAC-diPDI2 (4.24%). This result demonstrates that the conjugated degree of central core plays a vital role in the designing principle of ring-fusion.