Abstract
In this study we developed organic thin film transistors (OTFTs) for the sensing of metal ions and anions through the self-assembly of a pentacene/Schiff base pyrene derivative. Our bilayer OTFTs displayed attractive device parameters: an electron mobility (μ) of 0.12 cm 2 V -1 s -1 , a threshold voltage (V th ) of 22.20 V, and a five-orders-of-magnitude on/off ratio. This device was sensitive toward Cu 2+ among 13 metal cations and toward CN - among nine anions, as measured through changes in the values of V th and I off in the presence of Cu 2+ cations and a change in the value of I sat in the presence of CN - anions. We observed selectivity toward both of these ions in mixed ion solutions, with sensitivity over different concentrations (from 20 to 350 μM for Cu 2+ ; from 100 to 350 μM for CN - ) as well as in sea water. The pyrene derivative self-assembled through pyrene-pyrene * coordination in the presence of Cu 2+ ions; the rods of the pyrene derivative broke into smaller pieces upon formation of benzoxazole rings in the presence of CN - ions, as confirmed using atomic force microscopy and fourier transform attenuated total reflection spectroscopy.©2013 Elsevier B.V. All rights reserved.