인천대학교 인디고클랫폼 인천대학교 기술지원허브

While organic gas sensors exhibit distinct advantages such as mechanical flexibility and facile processability, they are often limited by inferior sensitivity compared to their inorganic counterparts. In this study, we demonstrate a straightforward and effective strategy to enhance the gas-sensing performance of poly(3- hexylthiophene) (P3HT) thin films by leveraging the coffee-ring effect induced during spray deposition. Our findings reveal that the surface roughness of P3HT films increases linearly with the number of spray passes, concurrent with a progressive increase in film thickness. Furthermore, by modulating the spray pressure from 0.12 MPa to 0.04 MPa, we show that lower pressure facilitates the formation of larger droplets, which enhances the coffee-ring effect upon drying. This process leads to cumulative stacking of droplet rims, consequently achieving a maximum root-mean-square roughness (Rq) of 46.3 nm. This morphological evolution ensures the formation of a continuous, rough surface structure that significantly expands the available active sites for gas adsorption. Although this rough morphology involves a trade-off in field-effect mobility due to increased grain boundaries, the engineered P3HT films exhibit higher responsivity and a low limit of detection (0.0431 ppm) toward NO2 gas compared to conventional smooth spin-cast films. This work presents a practical processing strategy to improve the performance of organic gas sensors through controlled surface morphology engineering.