Effect of Glass Fiber Membrane Support and PDA Interfacial Modification on NO2 Sensing in P3HT-Based OFETs

Poly(3-hexylthiophene) (P3HT) film-based organic field-effect transistor (OFET) gas sensors are attracting significant attention for environmental monitoring. However, conventional devices with dense and continuous active layers suffer from limited gas-sensing capabilities due to severe diffusion resistance. This study demonstrates a novel 3D channel architecture engineered by integrating a porous Glass Fiber Membrane (GFM) scaffold and a functional polydopamine (PDA) interfacial layer. Electrical characterization revealed that a 5-minute treatment (GFMP5) maintains a charge carrier mobility comparable to that of a bare P3HT film, bridging the trade-off between structural complexity and electronic integrity. Benefiting from accelerated analyte diffusion through the 3D fiber network and enhanced chemical trapping of NO₂ molecules via the PDA layer, the GFM 3D channel sensor exhibited improved sensing performance. Particularly, when exposed to 10 ppm NO₂ gas, the GFMP5 sensor demonstrated a dramatic increase in responsivity compared to bare P3HT and unmodified GFM/P3HT sensors, achieving a peak responsivity exceeding 240% vs. 60% and 100%, respectively. Furthermore, the device exhibited robust chemical selectivity toward NO₂ over common interfering gases such as CO₂, NH₃, and SO₂.