Facile One-Pot Direct Arylation Synthesis of Crystalline Additive Molecules for High-Efficiency Organic Solar Cells

Crystalline molecules (CMs) demonstrate tremendous potential in regulating the active layer morphology of organic solar cells (OSCs) through robust intermolecular interactions and the formation of highly ordered crystalline domains. As additives, CMs can effectively balance the crystallinity differences between polymers and small molecular acceptors while precisely controlling molecular stacking and phase separation processes, thereby constructing efficient charge transport channels and enhancing power conversion efficiency (PCE). However, the synthesis of most CMs involves complex multistep procedures, which hinders their widespread application. Here, we developed a facile one-pot direct arylation methodology for synthesizing CMs for high-efficiency OSCs, by preparing three structurally simple CMs (2TBT, 3TBT, and 4TBT), where 3TBT and 4TBT exhibit enhanced crystallinity and possess liquid crystalline (LC) properties. Upon incorporating these additives into PM6:L8-BO-based nonfullerene OSCs, the LC additives 3TBT and 4TBT enabled precise regulation of the active layer’s crystallinity, phase separation, and microstructure, while the non-LC additive 2TBT showed minimal morphological influence, highlighting the unique role of LC in morphological regulation. The aforementioned favorable morphological evolution simultaneously enhanced exciton dissociation and collection while promoting charge transport, resulting in an improvement of the device’s PCE from 17.00 to 18.12%. This work not only provides a convenient synthetic pathway for CMs and demonstrates that CM additives can effectively regulate the active layer of OSCs, but also offers a practical strategy for developing high-performance OSCs by leveraging their unique properties.