Pentacene-based thin film transistors with titanium oxide-polystyrene/polystyrene insulator blends: High mobility on high K dielectric films

High $K$ titanium oxide-polystyrene $\mathrm{Ti}{\mathrm{O}}_2\text{-}\mathrm{PS}$ nanocomposite has been blended with PS to generate gate dielectric films with permittivities ranging from 2.5 to 8 in order to investigate permittivity effects on pentacene thin film transistor performance. An order of magnitude increase in saturation mobility is observed for $\mathrm{Ti}{\mathrm{O}}_2\text{-}\mathrm{PS}$ $(K=8)$ as compared to PS devices $(K=2.5)$ . Morphological differences for pentacene grown on $\mathrm{Ti}{\mathrm{O}}_2\text{-}\mathrm{PS}∕\mathrm{PS}$ dielectrics are thought to be responsible for the observed mobility enhancements. The high performance of pentacene on $\mathrm{Ti}{\mathrm{O}}_2\text{-}\mathrm{PS}$ devices suggests that high permittivity films are compatible with high mobility devices.