Remarkably Stable, High-Quality Semiconducting Single-Walled Carbon Nanotube Inks for Highly Reproducible Field-Effect Transistors

In the past years, high-quality semiconducting single-walled carbon nanotube (s-SWCNT) inks obtained by conjugated polymer wrapping using toluene as solvent have been used for the fabrication of high-performance field-effect transistors. Charge-carrier mobilities up to 50 cm(2) V-1 s(-1) and on/off ratios above 10(8) have been reported for devices based on networks of s-SWCNT. However, devices fabricated from inks that are only a few weeks old generally show a marked decrease in performance, indicating the limited shelf life of toluene-based inks. The use of o-xylene as applicator solvent to obtain high quality and very stable s-SWCNT inks is reported. The charge carrier mobility of field-effect transistors fabricated with this new ink show a twofold increase in magnitude compared to devices prepared from a toluene solution. More importantly, the device-to-device performance shows improved reproducibility, which is ascribed to the higher degree of homogeneity of the s-SWCNT network deposited from o-xylene with respect to the one from toluene. Finally, the o-xylene inks maintain their initial properties for longer than one year. This very long shelf life is an important pre-condition for the industrial use of s-SWCNT inks.