Ionic Liquid-Assisted Ink for Inkjet-Printed Indium Tin Oxide Transparent and Conductive Thin Films

Drop-on-demand inkjet printing is used to deposit indium tin oxide (ITO) transparent and conductive thin films. ITO printable ink is prepared by dissolving indium hydroxide and tin (IV) chloride into ethanol with the assistance of acetic acid/tert-butylamine ionic liquid. Ionic liquid-assisted ITO ink exhibits a complete wetting behavior on the glass substrate and a tunable viscosity, which makes it particularly suitable for the inkjet printing fabrication of ITO thin films. After annealing at 500 °C in forming gas, ITO thin films with a sheet resistance of 99 Ω/□, a resistivity of 2.28 × 10–3 Ω·cm, and a transmittance of 95.2% in the range of 400–1000 nm can be obtained. The effects of annealing temperature on the resistivity, mobility, carrier concentration, transmittance, and optical band gap are investigated systematically. Compared with commercial ITO thin films made by conventional vacuum-based deposition approaches, these printable ITO thin films have a higher material utilization.