Solution-Processed Ambipolar Thin Film Transistors-Based Inverters for Circuit Applications

Fully solution-processed ambipolar organic thin-film transistors (OTFTs) are attractive for flexible, large-area, and low-cost electronics; however, their circuit-level implementation has remained limited by mobility imbalance, trap-induced instability, and complex fabrication. This study employs bulk-heterojunction blends of the benchmark n-type polymer N2200 and the high-mobility donor polymer DPP-DTT as a single active semiconductor platform for ambipolar OTFTs and complementary-like logic. Systematically tuning the DPP-DTT:N2200 composition enables balanced electron and hole transport, high on/off current ratios of ∼10⁵, and threshold voltages suitable for rail-to-rail operation, with the 5:95 blend providing the optimal compromise between mobility symmetry and operational stability. The optimized ambipolar behavior is attributed to a semi-intermixed morphology with bi-continuous percolation pathways and controlled crystallinity, as confirmed by correlated optical, energetic, and structural characterizations. Using a simple top-gate device architecture and geometry-scaled channel widths, all-polymer ambipolar inverters exhibited sharp switching voltage-transfer characteristics and high small-signal gains of up to 19 at an optimized width ratio of 2:1. This study establishes a manufacturing-compatible strategy for co-engineering blend composition, microstructure, and device geometry, enabling scalable printed organic logic using a single bulk heterojunction semiconductor rather than separate p-type and n-type materials.