Non-halogenated and polarized solid additives mediating the blend morphologies for efficient organic solar cells

The fine control of active blend morphologies is crucial to achieve efficient and stable organic solar cells (OSCs). Herein, by introducing structurally simple, non-halogenated volatile solid additives, we have demonstrated that the polar 2-naphthonitrile (2-CAN) additives help modulate the kinetics of blend morphological evolution during film drying. It is revealed that 2-CAN favorably interacted with acceptor moieties, and the transition from presence to absence of additives triggered the arrangement and aggregation of acceptors, hence yielding the ordered molecular stacks in the bulk heterojunction (BHJ) blends. Optimal blend morphologies with fibril networks were established to improve the excitonic and charge dynamics of active blends, enabling PM6:L8-BO binary OSCs with the promising efficiency of 19.08% (with 2-CAN), which outperformed that of devices with non-polar naphthalene (NA) additives (18.18%) or without additive treatments (17.43%). Meanwhile, non-halogenated 2-CAN exhibited excellent processing features of reproducibility and versatility toward different active blends for fabricating efficient devices. Such 2-CAN-assisted devices with robust transport layers allowed maintaining decent thermal stabilities under continuous 85 degrees C of thermal annealing. Overall, this work provides an effective strategy on tuning blend morphologies for efficient organic photovoltaics. (c) 2024 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights are reserved, including those for text and data mining, AI training, and similar technologies.