Studying the influence of thiophene derivatives on the difference between sorted semiconducting single-walled carbon nanotubes and ammonia sensing performance

Herein, we discussed that derivatives containing different thiophene units and their side-chain densities have been shown to differentiate between semiconducting single-walled carbon nanotubes (sc-SWCNTs) and gas sensing performance. Poly[(9,9′-dioctyl-2,7-fluorene-2,7) alt thiophene] (PFT), poly[(9,9′-dioctyl-2,7-fluorene) alt 2,5-bithiophene)] (PF8T2) and poly[(2,7-(9,9′-dioctyl-fluorene) alt 2,5-(3-dodecylthiophene)] (PF3DDT) were synthesized and used to compare the sorting effect of SWCNTs after composite with the three polymers. The reasons for the differences in the SWCNTs being sorted were further analyzed by DFT simulations. The analyses showed that increasing the side-chain length density was beneficial to sorting sc-SWCNTs when the main-chain structures of the polymers were the same, and the separation of sc-SWCNTs could also be increased by increasing the degree of conjugation of the main-chain structures of the polymers. Then, the gas-sensing performance for ammonia gas with the sorted materials was performed, and the differences in gas sensing performance of different polymer structures is discussed. Among them, PF8T2@Plasma showed a response of 48.5 % in 5 ppm ammonia vapor, which was the highest response to the target gas among the three complex materials. The limit of detection (LOD: 40.1 ppb) for PF8T2@Plasma's was the lowest among the three materials by theoretical calculation. Therefore, it would be a promising approach based on molecular structure design to enhance the gas sensing properties of materials. [Display omitted] •There was investigation of the structures of thiophene derivatives on the sorting of sc-SWCNTs.•Increasing the conjugated units of the polymer backbone facilitates the sorting of sc-SWCNTs.•The PF8T2@Plasma with a large conjugated structure had the best ammonia-sensing performance.•The PF8T2@Plasma showed a response value of 48.5% to 5 ppm ammonia vapors and the LOD of 40.1 ppb.