199. ORGANIC THIN-FILM TRANSISTORS FOR SELECTIVE HYDROGEN PEROXIDE AND ORGANIC PEROXIDE VAPOR DETECTION

Department: NanoEngineering
Faculty Advisor(s): Andrew Kummel

Primary Student
Name: James E Royer
Email: jeroyer@ucsd.edu
Phone: 858-534-3498
Grad Year: 2012

Abstract
Organic thin-film transistors (OTFTs) are promising candidates for selective chemical sensors due to numerous chemical and electrical parameters which govern sensor response. Analyte selectivity can be obtained using multiparameter electrical monitoring of a single OTFT which is sensitive to changes in mobility, Ion/Ioff ratio or threshold voltage. The present study demonstrates selective hydrogen peroxide and organic peroxide sensors with detection limits in the low parts-per-million range based on OTFT threshold voltage shifts. The threshold voltage shifts are observed for several vacuum-evaporated metal-phthalocyanine (MPc) based OTFTs as well as high-performance spin-coated naphthalocyanine OTFTs. The positive threshold voltage shift observed for peroxides is not evident with non-oxidizing analytes such as di-methyl methylphosphonate (DMMP) and background humidity. Furthermore, the positive threshold voltage shift responds linearly with the dose time, which permits dosimetric sensing analysis. The drain-source current (Ids) response to peroxides can be greatly enhanced using high-performance OTFTs operated at low gate voltages, near the device threshold voltage. A proposed mechanism for peroxide sensing is determined using simultaneous monitoring of mobility and threshold voltage. This detection method is exclusive for the OTFT platform and permits high selectivity at parts-per-million peroxide concentrations.

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