Detection of explosive analytes using a dendrimer-based field-effect transistor

Abstract

We report the detection of nitroaromatic vapors using a top-contact, bottom-gate organic field-effect transistor (OFET) by monitoring changes in the drain current. The active channel of the OFET contains a first generation dendrimer comprised of a spirobifluorene core, carbazole branching moieties, and fluorenyl surface groups. It is found that operating the device with pulsed gating reduces the bias stress and improves operational stability. p-Nitrotoluene (pNT) is used as the archetypical high electron affinity explosive analyte to demonstrate the sensing capability. Penetration and diffusion of pNT vapor into the dendrimer active channel is found to result in charge trapping and a resultant decrease of the carrier mobility and drain current. At room temperature the pNT is strongly bound to the dendrimer of the channel resulting in a prolonged and persistent response. However, the OFET performance is restored by heating the device at 80°C for 5min, which releases the pNT from the dendrimer layer.