High-mobility bottom-contact n-channel organic transistors and their use in complementary ring oscillators

The electrical characteristics of bottom-contact organic field-effect transistors fabricated with the air-stable $n$ -type semiconductor $N,N^{\prime }$ -bis(n-octyl)-dicyanoperylene-3,4:9,10-bis(dicarboximide) $\left(\mathrm{PDI}\text{-}8\mathrm{C}{\mathrm{N}}_2\right)$ are described. The mobility, threshold voltage, subthreshold swing, and $I_{\text{on}}∕I_{\text{off}}$ ratio($V_{DS}=40\mathrm{V}$ , $V_G=0\sim 40\mathrm{V}$ ) are $0.14{\mathrm{cm}}^2∕\mathrm{V}\mathrm{s}$ , $1.6\mathrm{V}$ , $2.0\mathrm{V}$ /decade, and $1.2\times {10}^3$ , respectively. The effect of electrode/dielectric surface treatment on these devices is also examined, with a combination of 1-octadecanethiol and hexamethyldisilazane. Organic complementary five-stage ring oscillators were fabricated using pentacene and $\mathrm{PDI}\text{-}8\mathrm{C}{\mathrm{N}}_2$ , and operated at an oscillation frequency of $34\mathrm{kHz}$ and a propagation delay per stage of $3\mu \mathrm{s}$ .