Templating openness engineering: A strategy for performance enhancement via synergistic nanocrystalline-amorphous composite in solution-processed InO_x/PEG TFTs

Metal oxide semiconductors offer high mobility and solution processability but suffer from brittleness. Polymer blending is a promising route to flexibility, yet the role of polymer chain segment distribution in microstructure control remains poorly understood. Here we introduce a “templating openness” strategy by systematically varying polyethylene glycol (PEG) chain length. Using multi-scale characterization including molecular dynamics (MD) simulations, ultraviolet–visible (UV–vis), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and thin-film transistors (TFT) measurements, we reveal that PEG chains in solution define a continuous template spectrum from fully open to quasi-closed. Short chains create disordered obstacle fields, degrading mobility. Long chains form single continuous obstacles, yielding oriented grains but mediocre performance. Medium-length chains self-assemble into semi-open grids, guiding fine uniform nanocrystals within a high-quality amorphous matrix that suppresses deep traps and enriches shallow donors, boosting mobility from 0.89 to 4.28 cm²/(V·s). Ultra-long chains form quasi-closed network cavities, enabling stable defect chemistry and robust enhancement across a wide concentration window. This work establishes a complete structure–property framework linking templating openness to device performance, providing a new paradigm for metal oxide/polymer semiconductor design based on physical chain-length regulation.