Towards a low cost fully integrated IGZO TFT NO2 detection and quantification: A solution-processed approach

Semiconducting metal oxide gas sensors that are inexpensive, room temperature operable are imperative for toxic gas and air pollution monitoring. The heating or continuous light activation requirements are unavoidable for these types of gas sensors. This paper reports for the first time a room temperature operable solutionprocessed In-Ga-Zn-O thin-film transistor (TFT) gas sensor to detect NO2 without continuous light activation. The TFT sensor exhibits promising sensing and selectivity towards NO2. The devices are re-generable and require light activation only to recover after exposure to the gas. Kelvin probe force microscopy characterization studies are performed to understand in detail the sensing mechanism of the solution-processed TFT device. A novel solution-processed TFT based gas-sensitive digital indicators that yield digital output quantifying the NO2 concentration are demonstrated. One of the integrated gas-sensitive digital indicators is developed using only two InGaZnO TFTs incorporating a signal conditioning circuit and analog to digital converter. Furthermore, it paves the way for portable, compact, and inexpensive systems for various gas sensing applications, including smart cities and sustainable ecosystems.

Automated summary

This study presents a novel room temperature operable gas sensor for detecting NO2 without continuous light activation, showing promising sensing and selectivity towards NO2. Kelvin probe force microscopy characterization was used to understand the sensing mechanism, and a gas-sensitive digital indicator was demonstrated for quantifying NO2 concentration. The research paves the way for portable, compact, and inexpensive gas sensing systems for various applications.