Preparation of poly(4-vinylphenol)/titanium dioxide composite and its application as a gate dielectric for organic thin-film transistors

Organic-inorganic composites can provide a unique feature combining superior dielectric properties of inorganic materials and solution processing capability of organic materials. In this study, poly(4-vinylphenol) (PVP) and titanium dioxide (TiO ₂) composite was prepared by mixing TiO ₂ nanoparticles in the PVP solution. In order to avoid severe gate-leakage currents in organic thinfilm transistors (OTFTs) with such a composite gate dielectric layer, poly(oxyethylene)(20)-sorbitane monooleate was used as a surfactant for uniform dispersion of TiO ₂ particles. The dispersion stability of TiO ₂ nanoparticles in the composite solutions was confirmed by observing its sedimentation time in the composite solutions. The composite dielectric film, fabricated by means of simple spincoating, provided an enhanced dielectric property and contributed to reducing the threshold voltage of OTFT, without augmenting the gate-leakage current. These results demonstrate that the fabricated composite dielectric film is essentially eligible for low-voltage operating OTFTs.