Sol‐Gel Processed Metal‐Organic Complex as Robust Hole‐Transporting Layer Enabling Efficient Organic Solar Cells

Abstract Inorganic metal oxides and salts are widely employed as hole‐transporting layers (HTLs) in organic solar cells (OSCs) due to their advantages of low cost and facile preparation. However, issues such as severe agglomeration can negatively impact film quality, leading to reduced reproducibility and device stability. To address these challenges, this work reports the synthesis of a vanadium trichloride‐benzene tricarboxylic acid (BTC) complex (denoted as VB) via a sol‐gel process under mild conditions (60 °C annealing). The VB film demonstrates well‐aligned energy levels and enhanced conductivity when integrated with the PM6:L8‐BO active layer. Consequently, binary OSCs incorporating the VB HTL achieve a high‐power conversion efficiency (PCE) of up to 19.60%. Notably, the sol‐gel processing technique offers a versatile approach for the fabrication of metal‐organic complex, resulting in a uniform and dense film. The robust coordination metal‐organic network structure of VB endows the VB‐based OSCs with exceptional thermal stability, as evidenced by a T 80 (PCE retention to 80% of the initial value) lifetime of 5142 h, which is among the best performances reported for state‐of‐the‐art OSCs.