Fabrication of an Organic Thin-Film Transistor by Inkjet Printing

Abstract

A nanocomposite as the gate insulating film of thin film transistors (TFTs) is prepared by blending cross-linked poly(4-vinylphenol) and high-k TiO 2 nanoparticles to enhance the permittivity of the gate dielectric and reduce operating voltage of TFTs. A pearl mill is used to grind up the agglomerations and dispersant to well stabilize the dispersion of the nanoparticles in the polymer matrix for inks. A dielectric film with the nanocomposite is made via mask-free inkjet printing. By adjusting the parameters of inkjet printing, including voltage, frequency, and waveform, a dielectric film with low roughness is accomplished after curing at 190 °C using an ink with 3 wt% TiO 2 . A pentacene-TFT with a top contact structure on a glass substrate is fabricated based on the inkjet-printed gate dielectric, which has a low leakage current density and a high current ratio. The TFT exhibits p-channel TFT characteristics with a high field-effect mobility (a saturation mobility of ~-0.49 cm 2 V -1 s -1 ) and low-voltage operation ( < 6 V), indicating that these nanocomposite dielectric materials can be used in low-cost high-performance printable electronics. © 2012 The Electrochemical Society.