Low-temperature all-vacuum-deposited interfacial layers for high-performance and reproducible flexible inverted organic solar cells and modules

Abstract

The lightweight, conformable nature of flexible organic solar cells positions them as a critical enabling technology for emerging application such as self-powered wearable electronics and distributed IoT networks. While recent breakthroughs have pushed rigid cell efficiencies beyond 20%, the reliance on solution-processed interlayers within direct device architectures presents a major bottleneck for translating high performance into flexible cells and scalable modules. Herein, we introduce a universal all-vacuum fabrication strategy for addressing the efficiency, scalability and stability challenges for flexible organic photovoltaics. We engineer the electron-selective interlayers via atomic layer deposition (ALD) of SnO2, achieving precise thickness control and exceptional uniformity across large area through optimized temperature and reaction kinetics. This approach yields a striking performance advantage over conventional sol gel-processed ZnO, achieve a champion efficiencies of over 18.5% (rigid) and 18% (flexible) with outstanding batch-to-batch reproducibility and stability. Crucially, we scale this architecture to series-connected modules with an aperture area of 15.6 cm² with a high geometric fill factor of 96.3%, achieve a record active-area rigid efficiency of 17.6%, demonstrating cell-to-module scaling losses within 5%. The process is also successfully transferred to PEN/ITO substrates, yielding flexible modules with an active-area PCE of 15.2% that retain >95% of their initial efficiency after 3,000 bending cycles at a 2-cm radius. This work establishes all-vacuum processing as a superior, scalable manufacturing route for high-performance organic solar modules, paving a direct pathway toward their commercial production.