This study focuses on the micro structural modifications of regioregular poly(3-hexylthiophene) (rr-P3HT) in the small active channel of thin-film transistors (TFTs) during operations. Polarized absorption and micro-Raman spectroscopy analyses allow us to probe directly the conformation transitions of rr-P3HT chains parallel or perpendicular to the channel by means of exciton bandwidth, interchain electronic coupling, and effective conjugation length. The results of absorption spectra and a joint experimental-theoretical study of Raman spectra show that an external source-to-drain electric field can align rr-P3HT chains parallel to the channel, improving electrical performance after long-term operations, especially charge transport properties. In comparison, the applied external gate field induced an increase in amorphous fraction of the rr-P3HT films. After the analysis, we propose a chain rearrangement model driven by an external electric field to interpret the changes of the effective conjugation length of rr-P3HT, rather than thermal annealing. Our observations provide a thorough explanation for the previously unknown relationships of structure-electronic properties under the extended operations of polymer TFT devices.
All Science Journal Classification (ASJC) codes
- Organic Chemistry
- Polymers and Plastics
- Inorganic Chemistry
- Materials Chemistry