Fabrication and Characterization of Self-Assembled Low Voltage Operated OTFT for H2S Gas Sensor for Oil and Gas Industry

The article examines the low-voltage organic thin film transistor’s (OTFTs) manufacturing and characterization process for hydrogen sulfide (H $_{\text{2}}$ S) gas sensing at room temperature and could be helpful at various emanating sites. The fabrication methodology utilizes a cost-efficient solution processed spin coating method for high- $\textit{k}$ dielectric (SrZrO $_{\text{x}}$ ) as a gate oxide and floating film transfer method (FTM) for silver nanoparticles doped PBTTT-C14 film for the active semiconductor layer. The developed spin-coated dielectric film offers a high capacitance of 433 nF/cm $^{\text{2}}$ with a high band gap of 4.95 eV. and also offers 0.1 nA/cm $^{\text{2}}$ leakage current density, which clarifies that the dielectric film has very less numbers of pin holes suitable for good-performing OTFT. The surface morphology of the dielectric film shows a very smooth dielectric film (rms roughness 0.245 nm), which demonstrates a high-quality dielectric/semiconductor interface offered by the dielectric film for the high performance of the device. On the other hand, the low-cost FTM deposited silver nanoparticles doped PBTTT-C14 active layer film is quite uniform (30 $\pm$ 3 nm thickness) and free from any anisotropic effect, which further improves the device performance for sensing applications. The developed sensor is deliberately characterized for H $_{\text{2}}$ S gas sensor shows a sensing response of 80% at 5 ppm. The sensor passes with a low detection limit of 15.17 ppb and exhibits a relative shift of 47.7% over 5 ppm H $_{\text{2}}$ S gas in threshold voltage. The developed device can be used in various gas emanating sites and oil industries.