Simultaneous Improvement of Efficiency and Stability of Organic Photovoltaic Cells by using a Cross‐Linkable Fullerene Derivative

Abstract Improving power conversion efficiencies (PCEs) and stability are two main tasks for organic photovoltaic (OPV) cells. In the past few years, although the PCE of the OPV cells has been considerably improved, the research on device stability is limited. Herein, a cross‐linkable material, cross‐linked [6,6]‐phenyl‐C61‐butyric styryl dendron ester ( c ‐PCBSD), is applied as an interfacial modification layer on the surface of zinc oxide and as the third component into the PBDB‐TF:Y6‐based OPV cells to enhance photovoltaic performance and long‐term stability. The PCE of the OPV cells that underwent the two‐step modification increased from 15.1 to 16.1%. In particular, such OPV cells exhibited much better stability under both thermal and air conditions because of the decreased number of interfacial defects and stable interfacial and active layer morphologies. The results demonstrated that the introduction of a cross‐linkable fullerene derivative into the interfacial and active layers is a feasible method to improve the PCE and stability of OPV cells.