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Updated: Aug 3, 2025

Monitoring the Effects of Illumination on the Structure of Conjugated Polymer Gels Using Neutron Scattering
Published on: December 21, 2017
Side-Chain-Assisted Transition of Conjugated Polymers from a Semiconductor to Conductor and Comparison of Their NO2
Yejin Ahn1, Sooji Hwang1, Hyojin Kye1
1Department of Organic and Nano System Engineering, Konkuk University, 120 Neungdong-ro, Seoul 05029, Republic of Korea.
Abstract:
To investigate the effect of a side chain on the electrical properties of a conjugated polymer (CP), we designed two different CPs containing alkyl and ethylene glycol (EG) derivatives as side chains on the same conjugated backbone with an electron donor-acceptor (D-A) type chain configuration. PTQ-T with an alkyl side chain showed typical p-type semiconducting properties, whereas PTQ-TEG with an EG-based side chain exhibited electrically conductive behavior. Both CPs generated radical species owing to their strong D-A type conjugated structure; however, the spin density was much greater in PTQ-TEG. X-ray photoelectron spectroscopy analysis revealed that the O atoms of the EG-based side chains in PTQ-TEG were intercalated with the conjugated backbone and increased the carrier density. Upon application to a field-effect transistor sensor for PTQ-T and resistive sensor for PTQ-TEG, PTQ-TEG exhibited a better NO2 detection capability with faster signal recovery characteristics than PTQ-T. Compared with the relatively rigid alkyl side chains of PTQ-T, the flexible EG-based side chains in PTQ-TEG have a higher potential to enlarge the free volume as well as improve NO2-affinity, which promotes the diffusion of NO2 in and out of the PTQ-TEG film, and ultimately resulting in better NO2 detection capabilities.
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