Dual‐Fibril Network Engineering for Scalable and Sustainable Organic Photovoltaics

Green-printed, high-efficiency organic photovoltaics modules are critical to the commercial expansion and practical deployment of organic photovoltaics. Since the emergence of Y6-based non-fullerene acceptors (NFAs), the power conversion efficiency (PCE) of OSCs is remarkable progress. However, a considerable performance gap remains between devices processed with halogenated versus non-halogenated (green) solvents, primarily due to difficulties in controlling molecular aggregation. Here, hydroxyl-rich cellulose acetate butyrate (CAB) is introduced as a multifunctional additive to enhance the morphology and performance of modules fabricated via large-area green printing. CAB suppresses excessive molecular aggregation and modulates the film-formation dynamics. Crucially, its hydroxyl side groups interact synergistically with both donor and acceptor materials to induce a dual-fibril network, providing abundant interfacial area for exciton dissociation and continuous pathways for efficient charge transport. As a result, green-printed PM6:PTP-eC9 devices achieve PCE of 19.04%. Moreover, ternary PM6:PTQ-10:PTP-eC9 devices and modules with an active area of 16.94 cm² exhibit PCEs of 20.23% and 17.26%, respectively. This work demonstrates a viable additive engineering strategy for realizing scalable, environmentally benign, and high-performance organic photovoltaics.