Liquid film spray deposition of transparent conducting oxide coatings

Abstract

A room temperature spraying technique was developed for the deposition of transparent conducting sol-gel ATO (antimony doped tin oxide, SnO2:Sb) coatings, based on an 0.2 M solution of SnCl2 in 1-propanol with 5 mol.% SbCl3 and a mixture of 2-isopropoxyethanol and 2-butoxyethanol as additives with a low evaporation rate. The selection of solvents and the adjustment of the evaporation rate are crucial to obtain uniform films and to avoid film defects like wetting problems or an orange peel effect. The ATO coatings were spray deposited manually on complex shaped substrates as well as on large area flat substrates with a size up to 21 x 30 cm2 by means of an industrial flat spray coater. The resulting ATO coatings are characterised by a thickness of up to 120 nm, a resistivity of approximately 2 x 10-2 Ω cm and a transmission T>85% in the visible, which is similar to the properties obtained for dip coated films.