Nanostructural Manipulation of Poly(3-hexylthiophene) Aggregates for Organic Electrolyte-Gated Transistors

In this study, we combine solubility-driven formation of poly(3-hexylthiophene) (P3HT) nanoaggregates and ion-gel-based organic electrolyte-gated transistors (OEGTs), to develop high-performance low-voltage switching devices. By in-situ solution blending of a good solvent (chloroform) and a poor solvent (acetone), we obtain dispersions of P3HT nanoaggregates. The aggregation and molecular ordering of P3HT are analyzed by UV-Vis absorption spectroscopy, atomic force microscopy imaging, and X-ray diffraction. The resulting P3HT aggregates are used as an active component of high-capacitance ion-gel dielectric based on P(VDF-HFP)/[EMIM][TFSI]. Wellconnected conductive channels in thin films of P3HT aggregates allow the effective modulation of current in ion gel-gated transistors with an on-state current above 10^-3 A at an operational voltage less than -1 V. In searching for the optimal ratio of solvents, the highest mobility of 1.36 cm² V^-1 s^-1 in the tested OEGTs was observed when 5 vol% of acetone was incorporated into the stock solution of P3HT. This observation suggests that the nanostructural manipulation of polythiophene-based semiconductor is an effective method to produce efficient pathways for charge transport in OEGTs.