Ambient Fabrication of Over 19% Efficient Organic Solar Cells via Spontaneous Water-Spreading and Layer-by-Layer Deposition

• • Achieved a record PCE of 19.02% for ambient-processed OSCs using D18:L8-BO, with a narrow efficiency distribution, indicating high reproducibility and industrial viability. • • Demonstrated scalability to 1 cm2 devices with a PCE of 16.56%, showing minimal efficiency loss (13.6% relative) upon area scaling, crucial for module manufacturing. • • Exhibited superior long-term stability: retained 84.1% of initial efficiency after 1000 hours of decay testing, addressing the operational lifetime bottleneck for commercial deployment. • • The water-spreading LBL technique enables precise vertical phase separation, enhancing charge transport and collection, as evidenced by improved fill factor and short-circuit current density.