Detection of H2O2 with Hygroscopic Insulator Organic Thin Film Transistor

Hygroscopic insulator field effect transistors (HIFETs) are a class of solid-state, low-voltage organic thin film transistors with promising sensitivity to hydrogen peroxide (H2O2). While work has progressed on the development and understanding of HIFET-based sensors, important questions regarding the fundamental H2O2 sensing mechanisms need to be fully investigated. In this work, a detailed study of the effects of H2O2 on the transient drain currents and transfer characteristics of HIFETs, while varying analyte concentrations and device voltages, is presented. The sensing mechanism is found to be consistent with the direct oxidation of the organic semiconductor channel, poly(3-hexylthiophene-2,5-diyl), by H2O2 diffused into the device through the permeable top gate electrode and hygroscopic insulator. Further, the importance of having a transistor structure in sensing H2O2, as compared to a two-terminal device, is demonstrated. These results represent important progress in the understanding of HIFET-based sensors, revealing paths for future applications and optimization.