Dual‐Fibril Network Engineering for Scalable and Sustainable Organic Photovoltaics

Abstract 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 cm 2 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.