Solution-Processed n-Type Organic Field-Effect Transistors With High on /off Current Ratios Based on Fullerene Derivatives

Solution-processed n-type organic field-effect transistors (OFETs) based on the fullerene derivative {6}-1-(3-(2-thienylethoxycarbonyl)-propyl)-{5}-1-phenyl-[5,6]-C61 (TEPP) and phenyl-C61-butyric acid methyl ester (PCBM) in a multiring source/drain structure are reported. Devices with TEPP show high electron mobility up to $\hbox{7.8}\times\hbox{10}^{-2}\ \hbox{cm}^{2}/\hbox{Vs}$ in the saturation regime for bottom-contact OFETs with Au S/D electrodes with a solution-processed fullerene derivative. The on/off ratios reported in this letter, which are in the range of $\hbox{10}^{5} -\hbox{10}^{6}$ , are among the highest values reported for such devices. This mobility is always higher compared to PCBM devices prepared in identical conditions. The mobility of TEPP and PCBM increased with increasing temperatures in the range of 100–300 K with activation energy of 78 and 113 meV, respectively, which suggests that the thermally activated hopping of electrons is dominant in TEPP.