Low-temperature processing of transparent conductive indium tin oxide nanocomposites using polyvinyl derivatives

摘要

We report on the influence of additives on the electrical, optical, morphological and mechanical properties of transparent conductive indium tin oxide (In_2O_3:Sn; ITO) nanopartide films by the use of polymers as matrix material. Key issues to fabricate layers suitable for use in electronic device applications are presented. Polyvinyl derivatives polyvinyl acetate, polyvinyl alcohol (PVA) and polyvinyl butyral were applied and their suitability to form transparent conductive ITO nanocomposite coatings at a maximum process temperature of 130 ℃ was investigated. A low-temperature treatment with UV-light has been developed to provide the possibility of curing ITO thin films deposited on substrates which do not withstand high process temperatures. Compared to best pure ITO layers (0.2 Ωcm~(-1)), the ITO-PVA nanocomposite coatings show a conductance value of 4.1Ω~(-1) cm~(-1) and 5.9 Ω~(-1) cm~(-1) after reducing in forming gas. Sheet resistance of ca. 1200 Ω/⇔ with coexistent transmittance of 85% at 550 nm for a layer thickness of about 1.45 μm was achieved. The conductance enhancement is a consequence of nanoparticulate ITO network densification due to the acting shrinkage forces caused by the polymer matrix during film drying and additionally UV-induced crosslinking of PVA.