Controllable ZnMgO Electron‐Transporting Layers for Long‐Term Stable Organic Solar Cells with 8.06% Efficiency after One‐Year Storage

Currently, one main challenge in organic solar cells (OSCs) is to achieve both good stability and high power conversion efficiencies (PCEs). Here, highly efficient and long‐term stable inverted OSCs are fabricated by combining controllable ZnMgO (ZMO) cathode interfacial materials with a polymer:fullerene bulk‐heterojunction. The resulting devices based on the nanocolloid/nanoridge ZMO electron‐transporting layers (ETLs) show greatly enhanced performance compared to that of the conventional devices or control devices without ZMO or with ZnO ETLs. The ZMO‐based OSCs maintain 84%–93% of their original PCEs over 1‐year storage under ambient conditions. An initial PCE of 9.39% is achieved for the best device, and it still retains a high PCE of 8.06% after 1‐year storage, which represents a record high value for long‐term stable OSCs. The excellent performance is attributed to the enhanced electron transportation/collection, reduced interfacial energy losses, and improved stability of the nanocolloid ZMO ETL. These findings provide a promising way to develop OSCs with high efficiencies and long device lifetime towards practical applications.