Deposition engineering enables highly efficient and stable organic solar cells

Organic solar cells (OSCs) have seen great progress in power conversion efficiencies (PCEs) recently. However, morphology tuning of the active layer remains challenging toward 20% mark. Layer-by-layer (LBL) approach is a newer way to tune morphology and achieve phase separation vertically. Herein, we construct a guest polymer-tailored LBL (GPT-LBL) strategy refining the p-i-n configuration, where a third polymeric guest PY-IT is utilized to in situ manipulate the pre-aggregation behaviors of acceptors. The GPT-LBL-based device exhibits enhanced charge transport and reduced energy loss. As a result, the optimal GPT-LBL OSC shows a high PCE of 19.41% (certified 19.0%) with an excellent FF of 81.3%, which is the record-certified LBL single-junction OSC. Impressively, the GPT-LBL-based device exhibited good scalability and operational stability. This work provides a novel approach to developing high-efficiency, large-area, and stable OSCs, accelerating the industrial development of OSCs