Long-term operations of polymeric thin-film transistors: Electricfield-induced intrachain order and charge transport enhancements of conjugated poly(3-hexylthiophene)

Horng Long Cheng, Jr Wei Lin, Ming Feng Jang, Fu Chiao Wu, Wei Yang Chou, Ming Hua Chang, Ching Hsun Chao

Research output: Contribution to journalArticlepeer-review

26 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)8251-8259
Number of pages9
JournalMacromolecules
Volume42
Issue number21
DOIs
Publication statusPublished - 2009 Nov 10

All Science Journal Classification (ASJC) codes

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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