Abstract
We investigate the electronic properties of solution-gated carbon nanotube (CNT) thin-film transistors, where the active layer consists of a randomly distributed single-walled CNT network of >90% semiconducting nanotubes, deposited from an aqueous solution by spin-coating. The devices are characterized in different electrolytic solutions, where a reference electrode immersed in the liquid is used to apply the gate potential. We observe a gate-potential shift in the transfer characteristic when the pH and/or ionic strength of the electrolytic solution is changed with a pH sensitivity of approximate to 19 mV/pH. This sensitivity is attributed to a surface charging effect at the CNT/electrolyte interface. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4768683]