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 (<inline-formula> <tex-math notation="LaTeX">$\text{H}_{{2}}\text{S}$ </tex-math></inline-formula>) 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-<inline-formula> <tex-math notation="LaTeX">${k}$ </tex-math></inline-formula> dielectric (SrZrOx) 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/cm2 with a high band gap of 4.95 eV. and also offers 0.1 nA/cm2 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 ± 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 <inline-formula> <tex-math notation="LaTeX">$\text{H}_{{2}}\text{S}$ </tex-math></inline-formula> 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 <inline-formula> <tex-math notation="LaTeX">$\text{H}_{{2}}\text{S}$ </tex-math></inline-formula> gas in threshold voltage. The developed device can be used in various gas emanating sites and oil industries.