Evaporation-Driven Deposition of ITO Thin Films from Aqueous Solutions with Low-Speed Dip-Coating Technique

We suggest a novel wet coating process for preparing indium tin oxide (ITO) films from simple solutions containing only metal salts and water via evaporation-driven film deposition during low-speed dip coating. Homogeneous ITO precursor films were deposited on silica glass substrates from the aqueous solutions containing In(NO₃)₃·3H₂O and SnCl₄·5H₂O by dip coating at substrate withdrawal speeds of 0.20-0.50 cm min^-1 and then crystallized by the heat treatment at 500-800 °C for 10-60 min under N₂ gas flow of 0.5 L min^-1. The ITO films heated at 600 °C for 30 min had a high optical transparency in the visible range and a good electrical conductivity. Multiple-coating ITO films obtained with five-times dip coating exhibited the lowest sheet (ρ_S) and volume (ρ_V) resistivities of 188 Ω sq^-1 and 4.23 × 10^-3 Ω cm, respectively.