P3HT/surfactant blend films in organic thin-film transistors for high-performance NO2 detection

The gas sensors based on organic thin-film transistor (OTFT) have drawn considerable attention due to the advantages of low-cost, flexible, and room-temperature operation. Herein, poly(3-hexylthiophene) (P3HT) blend with surfactants as an active layer for high-performance OTFT based nitrogen dioxide (NO2) sensors was reported. With the introduction of the surfactant (4-(1,1,3,3-Tetramethylbutyl)phenyl-polyethylene glycol, Triton), the gas sensors exhibited 7 times greater response to 30 ppm NO2 than pure P3HT films. The studies in morphology of the blend film reveal that a large number of grain boundaries (GBs) are formed by introduction of surfactants, which can promote the diffusion of NO2. In addition, the hydroxyl functional groups of the surfactants in blend films can efficiently adsorb polar molecules such as NO2, thus enhance the sensing performance. The gas sensors also showed great potential for ultralow concentration detection with a response of 61% to 500 ppb, which are important for the practical applications. This work demonstrates that the surfactants can be applied to improve the NO2 sensors with simple solution process, which expands the material choice of OTFT based gas sensors.