Pressure‐Controlled Nanoimprint Lithography Achieves over 20% Efficiency in Organic Solar Cells

Abstract Nanoimprint lithography (NIL) offers unprecedented control over active layer morphology in organic solar cells (OSCs), yet optimal processing conditions remain critical for maximizing device performance. Here, pressure‐dependent NIL fabrication of ordered interdigitated heterojunction structures is demonstrated in D18/L8‐BO‐based OSCs, achieving exceptional performance through systematic pressure optimization. At an optimal pressure of 50 bar, devices exhibit record‐setting metrics: 20.08% power conversion efficiency, 27.34 mA cm⁻² short‐circuit current density, and 80.34% fill factor. The NIL‐patterned active layers form well‐defined, solvent‐resistant nanopillar arrays (8.7–29 nm height) with enhanced light‐harvesting capabilities. Detailed characterization reveals improved molecular ordering in both donor and acceptor phases, while advanced spectroscopy demonstrates accelerated charge transfer dynamics with reduced exciton dissociation and diffusion times. This pressure‐optimized NIL strategy simultaneously enhances the optical, morphological, and electronic properties of OSCs, establishing a promising pathway toward commercial‐scale organic photovoltaic technology.