Nonsolvent immersion-driven porous structuring of P3HT films for enhanced gas adsorption

Conjugated polymers are promising sensing materials for portable sensors because of their mechanical flexibility, low mass, and cost-effective processing, which are essential for next-generation devices such as electronic skins. However, despite these advantages, gas sensors based on conjugated polymers remain difficult to commercialize due to their limited gas sensitivity. This study introduces a strategy to enhance sensitivity by forming a porous structure in the poly(3-hexylthiophene) (P3HT) active layer through a simple nonsolvent immersion process, thereby increasing the density of gas-molecule adsorption sites. Among the tested nonsolvents, n-hexane (R a = 8.6 MPa 1/2 ), which exhibits the smallest solubility distance from P3HT, produced the deepest and widest pore morphology and the highest surface roughness (R q = 2.98 nm), leading to a maximized effective surface area. As a result, the n-hexane-treated film exhibited the highest sensitivity to NO 2 , achieving an approximately fourfold enhancement compared with the pristine P3HT film. These results demonstrate an effective approach for tuning surface area through a simple processing route and provide a viable surface-engineering strategy for high-performance organic gas sensors. • Nonsolvent immersion controls P3HT nanomorphology and surface roughness. • n-Hexane acts as a marginal solvent, facilitating the formation of porous networks. • n-Hexane treated porous film showed highest NO 2 sensitivity with LOD of 0.017 ppm. • This surface engineering offers a practical route for high-performance sensor.