Boosting Efficiency and Stability of Air‐Processed Blade‐Coated All‐Polymer Organic Solar Cells Based: The Role of Electron Transport Layer and Additives

All‐polymer organic photovoltaics (all‐PSCs), in which both donor and acceptor are conjugated polymers, have recently achieved power conversion efficiencies (PCEs) approaching ~19%, thanks to nonfullerene acceptor polymers such as PY‐IT. However, these high performances are still mainly obtained via spin‐coating and halogenated solvents, which limits scalability and environmental compatibility. Developing efficient devices under green, air‐processed conditions therefore remain a key challenge, particularly due to the strong sensitivity of polymer morphology. Here, we investigate PM6:PY‐IT‐based all‐PSCs processed by air doctor‐blade coating using o‐xylene as a nonhalogenated solvent, together with a PM6:Y12 binary reference and an advanced ternary PM6:Y12:PY‐IT system. We systematically examine the influence of electron transport layers (PDINN, PFN‐Br, and PNDIT‐F3N) and processing additives (Tetralin and DMN) on morphology, charge transport, device performance, and stability. The devices are characterized using J – V measurements, grazing‐incidence wide‐angle X‐ray scattering, atomic force microscopy, space‐charge‐limited current, and ISOS‐D‐1, ISOS‐D‐2, and ISOS‐L‐1 protocols. PM6:PY‐IT devices processed with DMN reach a PCE of 16.58% in small areas, and 10.91% upon scaling to 1 cm 2 . DMN enhances molecular ordering, crystallinity, and charge transport compared to Tetralin, particularly in PY‐IT‐based systems, leading to higher fill factors and performances. While the highest efficiency is obtained with PDINN, PNDIT‐F3N offers the best balance between efficiency and stability.