Long-Term Operations of Polymeric Thin-Film Transistors: Electric-Field-Induced Intrachain Order and Charge Transport Enhancements of Conjugated Poly(3-hexylthiophene)

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• 作者：Horng-Long Cheng ; Jr-Wei Lin ; Ming-Feng Jang ; Fu-Chiao Wu ; Wei-Yang Chou ; Ming-Hua Chang ; Ching-Hsun Chao
• 刊名：Macromolecules
• 出版年：2009
• 出版时间：November 10, 2009
• 年：2009
• 卷：42
• 期：21
• 页码：8251-8259
• 全文大小：991K
• 年卷期：v.42,no.21(November 10, 2009)
• ISSN：1520-5835

文摘

This study focuses on the microstructural 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.