Improved NO2 Gas-Sensing Performance of an Organic Field-Effect Transistor Based on Reduced Graphene Oxide-Incorporated Nanoporous Conjugated Polymer Thin Films

In this study, we have described a simple method for enhancing the NO2-sensing performance of the organic field-effect transistor (OFET) sensors at room temperature through reduced graphene oxide (rGO)-incorporated nanoporous P3HT films using the shear coating-assisted phase separation technique. The morphologies, microstructures, photophysical properties, and electrical properties of rGO-incorporated nanoporous P3HT films were investigated by atomic force microscopy, optical microscopy, ultraviolet–visible spectroscopy, X-ray diffraction analysis, Raman spectroscopy, and charge-carrier mobility measurements. The synergistic effect of P3HT pores acting as analyte diffusion pathways and rGO acting as adsorption sites resulted in a significant variation of the electrical properties of nanoporous P3HT/rGO OFETs upon exposure to NO2 gas molecules, indicating the potential of OFETs as efficient NO2 sensors. Specifically, the new nanoporous OFET sensors based on rGO-incorporated nanoporous P3HT films exhibited significantly improved responsivity with a value of ∼61.3% for 10 ppm NO2 gas compared to those based on nonporous P3HT/PS/rGO composite films (∼17.7%). Moreover, excellent response and recovery behaviors (response time = ∼62 s and recovery time = ∼145 s), high sensitivity (∼1.48 ppm–1), and good selectivity were observed.