Integrated Omnidirectional Design of Non‐Volatile Solid Additive Enables Binary Organic Solar Cells with Efficiency Exceeding 19.5 %

Abstract Solid additives have drawn great attention due to their numerous appealing benefits in enhancing the power conversion efficiencies (PCEs) of organic solar cells (OSCs). To date, various strategies have been reported for the selection or design of non‐volatile solid additives. However, the lack of a general design/evaluation principles for developing non‐volatile solid additives often results in individual solid additives offering only one or two efficiency‐boosting attributes. In this work, we propose an integrated omnidirectional strategy for designing non‐volatile solid additives. By validating the method on the 4,5,9,10‐pyrene diimide (PyDI) system, a novel non‐volatile solid additive named PyMC5 was designed. PyMC5 is capable of enhancing device performance by establishing synergistic dual charge transfer channels, forming appropriate interactions with active layer materials, reducing non‐radiative voltage loss and optimizing film morphology. Notably, the binary device (PM6 : L8‐BO) treated by PyMC5 achieved a PCE over 19.5 %, ranking among the highest reported to date. In addition, the integration of PyMC5 mitigated the degradation process of the devices under photo‐ and thermal‐stress conditions. This work demonstrates an efficient integrated omnidirectional approach for designing non‐volatile solid additives, offering a promising avenue for further advancements in OSC development.