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Optimization of Nanoparticulate Indium Tin Oxide Slurries for the Manufacture of Ultra-Thin Indium Tin Oxide Coatings with the Slot-Die Coating Process
M. Wegener, K. Riess, A. Roosen
University of Erlangen-Nuremberg, Department of Materials Science, Glass and Ceramics, Martensstr. 5, D-91058 Erlangen, Germany
received June 15, 2015, received in revised form July 21, 2015, accepted July 31, 2015
Vol. 7, No. 1, Pages 29-38 DOI: 10.4416/JCST2015-00026
Abstract
This paper deals with the optimization of colloidal processing to achieve suitable nanoparticulate indium tin oxide (ITO) slurries for the production of sub-µm-thin ITO coatings with the slot die coating process. For application in printed electronics these ITO coatings, which are composite films consisting of nanoparticulate ITO and a polymeric binder, should offer high flexibility, transparency and electrical conductivity. To preserve their flexibility, the composite films are not subject to any heat treatment, instead they are used as deposited and dried. To achieve very good transparency and electrical conductivity at the same time, the slurries must exhibit excellent dispersivity to result in a dense particle packing during film formation and drying. To reduce materials costs, films with thicknesses of several 100 nm are of interest. Therefore, the slot-die technique was applied as a fast, pre-dosing technique to produce sub-µm-thin ITO/binder composite films. The resulting ITO/binder films were characterized with regard to their key properties such as total transmission and specific electrical resistance. With the colloidal optimization of ethanol- and water-based nanoparticulate ITO slurries using PVP and PVB as binders, it was possible to achieve films of 250 nm in thickness exhibiting high total transmission of ∼ 93 % and a low specific electrical resistance of ∼ 10 Ω·cm.
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Keywords
Nanoparticulate indium tin oxide (ITO), slot-die coating technology, nanocomposite polyvinyl butyral (PVB), polyvinyl pyrrolidone (PVP)
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