Streamlined Y6-Analogs Enabling Efficient Ambient-Air-Processed Organic Solar Cells

Abstract

Achieving high efficiency and long-term stability under ambient processing conditions remains a critical hurdle for the commercialization of organic solar cells (OSCs). Here, we report two new Y6-analogs-BT(BO)-v-T(C12)-4F (4F) and BT(BO)-v-T(C12)-4Cl (4Cl)-featuring vinylene (v)-bridged DA ' D cores, designed to improve the material's scalability while maintaining the structural advantages of Y6-type acceptors. Morphological and device-level investigations reveal that these M-Y6 derivatives facilitate thermodynamically stable molecular packing and favorable crystalline orientation, even when fully processed in air. Incorporation of 4F into a layer-by-layer ternary architecture with D18/L8-BO via a reproducible air-processing protocol results in a certified power conversion efficiency (PCE) of 19%, among the highest reported for conventional OSCs fabricated under ambient conditions. Moreover, 4F-based devices demonstrate exceptional thermal and photostability, retaining over 80% of their initial PCE after extended aging under the ISOS-L-1 protocol without encapsulation. These improvements are attributed to the enhanced crystallinity, vertical molecular alignment, and morphological robustness imparted by the 4F acceptor. This study identifies BT(BO)-v-T(C12)-4F as a promising air-processable acceptor for scalable OSCs that combine high efficiency with long-term operational durability.