Enhanced Polymer Thin Film Transistor Performance by Carefully Controlling the Solution Self‐Assembly and Film Alignment with Slot Die Coating

Polymer‐based organic semiconductors inherently facilitate solution processing and have the mechanical robustness necessary for printable and large area applications. In order to achieve large area solution‐processed high‐performance polymer based devices, controlling the crystallization and self‐assembly behavior of the polymer thin films through solution processing method is desirable. Here, well controlled diketopyrrolopyrrole‐thieno[3,2‐b]thiophene copolymer (DPPT‐TT) thin films are developed using slot die coating controlled self‐assembly. The thin film morphologies and microstructure are investigated in details. This well‐defined morphology is rationalized in terms of the strong intermolecular interactions. The organic thin film transistors (OTFTs) with these controlled thin films are fabricated and exhibited charge carrier mobilities of 4.6–7.2 cm2 V−1 s−1 for the slot die coating controlled devices when measured in ambient air and up to 8.9–10.2 cm2 V−1 s−1 when measured in nitrogen. When applying native grown AlO x as gate dielectric, the OTFT achieves a mobility of 2.0 cm2 V−1 s−1 at the operating voltage ≤−3 V.