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

Abstract

The lightweight and conformable nature of flexible organic solar cells positions them as a critical enabling technology for emerging applications 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 of flexible organic photovoltaics. We engineer electron-selective interlayers via atomic layer deposition (ALD) of SnO₂, achieving precise thickness control and exceptional uniformity over large areas through optimized temperature control and reaction kinetics. This approach yields a striking performance advantage over conventional sol–gel-processed ZnO, achieving a champion efficiency of over 18.5% (rigid) and 18% (flexible), along with outstanding batch-to-batch reproducibility, storage stability and mechanical durability. Crucially, we scale this architecture to series-connected modules with an aperture area of 15.6 cm² and a high geometric fill factor of 96.3%, achieving a record active-area rigid efficiency of 17.6%, demonstrating cell-to-module scaling losses below 5%. This 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 3000 bending cycles at a bending radius of 1.5 cm. 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.