A solution process for preparation of low resistance layered indium tin oxide films

• Indium tin complex decomposition into indium tin oxide (ITO) was examined.
• Thermal treatment in a 2-zone atmosphere controlled inline kiln was investigated.
• Atmospheric [O2] during indium tin complex decomposition influenced ITO morphology.
• Alternating nanoparticle/complex layer stacked films gave low resistance ITO films.
• One step precursor decomposition and annealing in forming gas was achieved.

Continuous indium tin oxide (ITO) films of as low as 10 Ω/□ and up to ~ 2 μm thick were prepared by forming a laminate structure of alternating indium tin complex and ITO nanoparticle layers on a substrate by solution deposition then thermal transformation of the precursor film to ITO. The characteristic formation of a dense ITO layer on the surface of ITO films was observed upon decomposition of 3,4-dihydroxybenzoate ester complexes of indium tin, which were found to become more crystalline when transformed under a reduced oxygen atmosphere at a controlled heating rate. The observed dense ITO skin formation characteristic was used in combination with sequential direct transfer to a reductive atmosphere in a two zone inline kiln to give low resistance stacked ITO films in a one-bake process. Photo-patternable indium tin complexes were also used to form the dense ITO skin on top of the stacked structure.