Incorporation of Nanodroplets into Semiconducting Polymer Layers to Improve the Performance of Organic Electrolyte-Gated Transistors

Organic electrolyte-gated transistors (OEGTs) used as a high-capacitance electrolyte dielectric for low-voltage electronics often exhibit the phenomenon of unintentional electrochemical doping (i.e., ion migration throughout the semiconductor) that degrades the device due to ion penetration into the semiconductor layer. Here, we describe a simple method to fabricate a semiconducting polymer layer by incorporating ionic liquid nanodroplets to reduce ion migration into the active (semiconductor) layer. We use poly(3-hexylthiophene) (P3HT) as a semiconducting polymer layer and butyl-3-methylimidazolium tricyanomethanide ionic liquid (BMIM-TCM) as a gate insulator. P3HT semiconductor dissolved in trichlorobenzene (TCB) is cast from a mother solution mixed with a small amount of ionic liquid (IL) dissolved in chloroform (CF) as a nanodroplet component. IL nanodroplets dispersed in P3HT ensure local charge balance in the active layer and thus reduce slow electrochemical transport processes under applied voltage biases. In this work we show the small hysteresis and threshold voltage compared to a pristine P3HT device without IL nanodroplets.