Solution-Processed, Highly-Efficient Organic Field-Effect Transistor Based Hydrogen Sulfide Gas Sensor at Sub-ppm Regime

In the current article, we have investigated a highly selective, sensitive, low-power, and cost-efficient hydrogen sulfide (H
₂
S) gas sensor utilizing the thin film of conjugated organic polymer poly[2,6-(4,4-bis-(2-ethylhexyl)- 4H-cyclopenta [2,1-b; 3,4-b’] dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT) as an active sensing layer. The organic thin film of PCPDTBT polymer is developed using a cost-effective, facile solution-processed floating film transfer method (FTM). In addition, the state-of-the-art technique used for annealing named “solvent vapor annealing” offers enhanced crystallinity and excellent charge transfer along the polymer chain which significantly improves sensitivity. The fabricated organic field effect transistor (OFET) with top contact bottom gate (TCBG) configuration is thoroughly explored to investigate the thin film’s electrical and gas sensing performance for toxic and hazardous H
₂
S gas. The fabricated device worked at room temperature (RT-25 °C) and was highly sensitive to the presence of H
₂
S gas at concentrations even lower than 1 ppm. The fabricated OFET device has excellent air stability, good response–recovery behavior (response/recovery time of 8/250 s, respectively), exceptional gas response reproducibility, and a high sensor response of 71.3% at 1 ppm H
₂
S gas exposure.