Hybrid gate dielectrics: a comparative study between polyvinyl alcohol/ $$\hbox {SiO}₂$$ SiO 2 nanocomposite and pure polyvinyl alcohol thin-film transistors

Polyvinyl alcohol (PVA) thin films as polymer gate dielectrics, with and without (hbox {SiO}₂) nanoparticles were fabricated using spin-coating. Surface roughness and hydrophilicity of PVA and PVA/(hbox {SiO}₂) thin films were studied by contact-angle measurements and atomic force microscopy. The dielectric properties were characterized via capacitance and leakage-current measurements on metal–insulator–metal structures. In order to further investigate the application potential of such materials as a replacement for conventional inorganic dielectrics such as (hbox {SiO}₂) in organic thin-film transistors, devices were fabricated based on these polymers using (upalpha ), (upomega )-dihexylquaterthiophene as an active layer. Performance of the devices was realized by electrical measurements and Kelvin probe force microscopy. All transistors showed hole and electron mobilities in the low-voltage range. PVA/(hbox {SiO}₂) films showed larger capacitance, less hydrophilicity, rougher surfaces and considerable leakage currents compared with those with neat PVA. Although integrating nanoparticles modified surface electronic properties and showed a shift in surface potential as observed in Kelvin probe force measurements, it appears that non-polymeric and neat polymeric dielectric materials could still be a privilege to nanocomposite polymeric dielectrics for optoelectronic applications.