| AVS 58th Annual International Symposium and Exhibition | |
| Electronic Materials and Processing Division | Thursday Sessions |
| Session EM+TF-ThM |
| Session: | Hybrid Electronic Materials and Interfaces |
| Presenter: | James Royer, University of California San Diego |
| Authors: | J. Royer, University of California San Diego E. Kappe, University of California San Diego W. Trogler, University of California San Diego A.C. Kummel, University of California San Diego |
| Correspondent: | Click to Email |
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, and/or threshold voltage. The present study demonstrates selective hydrogen peroxide and organic peroxide sensors based on irreversible metal-phthalocyanine (MPc) OTFT threshold voltage shifts. The irreversible threshold voltage shift is not evident with non-oxidizing analytes such as di-methyl methylphosphonate (DMMP) and common background analytes such as water vapor. Furthermore, the threshold voltage shift responds linearly to the dose time which permits dosimetric sensing analysis. A proposed mechanism for peroxide sensing is determined using simultaneous monitoring of mobility and threshold voltage. The data reveal reversible mobility and irreversible threshold voltage response. Mobility response time is fast and saturates quickly whereas threshold voltage response is dosimetric, and irreversible, suggesting an accumulation of uncompensated positive charge in the MPc film. The results are consistent with a dual response adsorption/decomposition mechanism in which the peroxide reversibly decreases mobility through a molecular chemisorption event and irreversibly shifts threshold voltage due to electron transfer from the MPc to peroxide. The electron transfer from the MPc to peroxide dissociates the peroxide to form hydroxyl products and leaves an uncompensated MPc+. This detection method is exclusive for the OTFT platform and permits high selectivity at low peroxide concentrations.