Oxygen-bearing functionalities enhancing NO₂, NH₃, and acetone electronic response and response variation by polythiophenes in organic field-effect transistor sensors

Abstract

We investigated the enhanced vapor responses and altered response ratios of a series of thiophene (co)polymers with oxygenated side chains (CH2OH, linear polyethylene glycol, and crown ether), including the novel...

NO2 Exposure Effect on Mixed Conductivity and Seebeck Coefficient in Thiophene Polymers

“…Additionally, power factors for 40 nm thick P3HT samples (shown in Figure S2c) are not necessarily reliable because of the low conductivities, and the corresponding series resistances would decrease their utility. As shown in Figure a,c, power factors for PT-COOR and PT-OH show more regular increases with σ, consistent with mobility increasing as a result of NO 2 exposure. ,, The initial PF of PT-COOR was 0.052 ± 0.0044 μW/mK 2 while that of PT-OH was 0.045 ± 0.0053 μW/mK 2 . The PFs of PT-COOR and PT-OH were increased to 0.40 ± 0.14 and 0.68 ± 0.15 μW/mK 2 , respectively.…”

“…The degree of side chain acidity plays a major role in the absorption mechanism (functional group acidity rank: −COOH > −OH ≫ −COOR ≫ −(CH 2 ) 5 CH 3 ). Compared to the alkyl groups on the P3HT side chain, the polar oxygenated functional groups on three other polythiophene side chains have significantly facilitated the interactions between the polar dopant and the polymers . Furthermore, both PT-COOH and PT-OH are mixed conductors and are acting as sources of protons during NO 2 exposure. , Our previous work explained that for PT-COOH NO 2 dopants were able to facilitate both the hole and proton transport along the carboxylic acid side chains .…”

“…Compared to the alkyl groups on the P3HT side chain, the polar oxygenated functional groups on three other polythiophene side chains have significantly facilitated the interactions between the polar dopant and the polymers . Furthermore, both PT-COOH and PT-OH are mixed conductors and are acting as sources of protons during NO 2 exposure. , Our previous work explained that for PT-COOH NO 2 dopants were able to facilitate both the hole and proton transport along the carboxylic acid side chains . What makes PT-COOH more conductive than PT-OH is that during vapor exposure carboxylic acid groups are more likely to release protons and form stable carboxylate ions compared to the less acidic hydroxyl groups.…”

“…In this paper, we systematically studied and analyzed the change in thermoelectric performance of four alkylthiophene polymers that each served as the active sensing layer of a gas sensor after exposing to a wide range of NO 2 concentrations. As the FET and chemiresistive properties of the four polymers have been extensively studied in our previous publications, ,, this paper serves as an extension to our previous work and is devoted to measuring thermoelectric parameters and analyzing their correlations.…”

“…As shown in Figure 5a,c, power factors for PT-COOR and PT-OH show more regular increases with σ, consistent with mobility increasing as a result of NO 2 exposure. 23,40,41 The initial PF of PT-COOR was 0.052 ± 0.0044 μW/mK 2 while that of PT-OH was 0.045 ± 0.0053 μW/mK 2 . The PFs of PT-COOR and PT-OH were increased to 0.40 ± 0.14 and 0.68 ± 0.15 μW/mK 2 , respectively.…”