In this section
@inproceedings{Lee:2005:10.1109/DRC.2005.1553096,
author = {Lee, JB and Heeney, M and Tierney, S and McCulloch, I and Murphy, A and Liu, J and Fréchet, JMJ and Subramanian, V},
doi = {10.1109/DRC.2005.1553096},
pages = {147--148},
title = {Polythiophene thin-film transistor array for gas sensing},
url = {http://dx.doi.org/10.1109/DRC.2005.1553096},
year = {2005}
}
TY - CPAPER
AB - A small array of various polythiophene derivative OTFT gas sensors with robust operation in air is demonstrated. Air stability is shown not to preclude gas sensor response, and good sensitivity to a range of gas analytes is observed down to 10 ppm. The active materials are all deposited from solution, making these sensors compatible with low-cost gas sensor arrays. Finally, the effect of varying the functional groups and size of a gas analyte on the response it induces in the sensor array is investigated. Organic thin film transistors (OTFTs) are an attractive option for low-cost gas sensor arrays. The synthetic richness of organic chemistry allows the development of arrays of materials with systematically varied ranges of sensitivities. Also, organic sensing materials tend to be soluble, and arrays of sensors can thus be cheaply integrated onto a single substrate through inkjet deposition. However, stability of OTFTs is a concern, especially for operation in ambient conditions. Encapsulation is not an option for gas sensors, so the development of air-stable materials is important, but the trade-off between air-stability and odor sensitivity is unclear and requires further study. A schematic cross section of the OTFT gas sensors is shown in Figure 1. For convenience, a standard substrate-gated architecture was used. 95 nm of wet oxide is grown on heavily doped Si substrates, and 50 nm thick Au pads with a 2.5 nm Cr adhesion layer are thermally evaporated to form source/drain contacts. The active materials, including poly-3-hexylthiophene (P3HT) and two air-stabilized polythiophene derivatives (M2 and P1), are deposited by spin-coating. Sensors are operated at room temperature in the dark, in an isolated chamber with controlled gas flow, and probed remotely with an HP 4145 parameter analyzer. The sensors show appreciable response to air, exhibiting large, repeatable shifts in on-current, mobility, and threshold voltage when purged with nitrogen or reexposed to air. A
AU - Lee,JB
AU - Heeney,M
AU - Tierney,S
AU - McCulloch,I
AU - Murphy,A
AU - Liu,J
AU - Fréchet,JMJ
AU - Subramanian,V
DO - 10.1109/DRC.2005.1553096
EP - 148
PY - 2005///
SN - 1548-3770
SP - 147
TI - Polythiophene thin-film transistor array for gas sensing
UR - http://dx.doi.org/10.1109/DRC.2005.1553096
ER -