Enhanced and Anisotropic Charge Transport in Polymer-Based Thin-Film Transistors by Guiding Polymer Growth

Ideal molecular features and microstructural properties of organic semiconducting thin films are being explored to achieve high-performance organic thin-film transistors (OTFTs). We prepared and processed hexamethylbenzene (HMB)/poly(3-hexylthiophene) (P3HT) mixtures using a thermal gradient system to fabricate P3HT-based OTFTs. In the thermal gradient system, the HMB separated from the HMB/P3HT mixtures and crystallized along the sample movement direction. The crystallized HMB affected and guided the growth behavior of P3HT at the molecular level. Observations from joint microscopic and spectroscopic analyses revealed that the HMB-processed P3HT (H-P3HT) thin film possessed anisotropic and improved microstructures, particularly in crystalline domains. The improved molecular features and microstructural properties of the H-P3HT thin film enhanced the intramolecular and intermolecular charge transport by extending the π-conjugation, decreasing the reorganization energy, and strengthening the π–π overlaps. ...