Organic field-effect transistor-based (OFET) sensors show promise as flexible, lightweight, highly-sensitive pollutant gas detectors that could potentially be incorporated into portable and wearable technology. However, the instability of these organic sensors at room temperature have so far limited their applicability when compared to inorganic sensors, which lack the flexibility and lightweight nature of OFETs. Researchers at Incheon National University have developed a potential solution to this dilemma, producing a hybrid OFET sensor made from both organic and inorganic materials to improve stability while retaining the positive qualities of organic materials.
The hybrid sensors, designed to detect nitrogen oxide (NO2), are made from the organic conjugated polymer poly(3-hexylthiophene), or P3HT, and variations of the inorganic nanoporous material zeolite. The researchers produced one sensor using the zeolite variant PST-11 and one with zeolite Omega. This combination resulted in a lightweight and flexible film due to the P3HT matrix as well as strong adsorption of small gas molecules due to the zeolite nanopores. Additionally, the zeolite’s ability to adsorb oxidizing molecules increases the durability of the sensor.
The researchers tested the two versions of the sensor by exposing them to NO2 gas and found that both hybrid OFETs showed high sensitivity in detecting the gas. The team found that the PST-11-P3HT film was more sensitive than the Omega-P3HT film due to its larger specific surface area. This study was published in the Chemical Engineering Journal.
“Our approach represents a new way of conceptualizing the design and development of sensors. If our research is refined further, people can easily detect harmful gases in real time,” said lead researcher Yeong Don Park. “Our devices can be integrated with wearable devices such as smart watches and e-skins to allow people to know about air pollution levels in areas other than industrial sites.”
The hybrid design provides an orderly structure that increases the efficiency of the sensor’s NO2 detection. Zeolite-based materials could potentially be applied to the creation of further OFETs that detect pollutant gases, the researchers wrote.