Synthesis,Structures, and Properties of Fused Thiophenes for Organic Field‐Effect Transistors |
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Authors: | Ying Liu Chong‐an Di Dr. Chunyan Du Yunqi Liu Prof. Kun Lu Wenfeng Qiu Dr. Gui Yu Prof. |
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Affiliation: | 1. CAS Key Laboratory of Organic Solids, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China), Fax: (+86)?10‐6255‐9373;2. Graduate School of the Chinese Academy of Sciences, Beijing 100039 (China) |
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Abstract: | A series of fused thiophenes composed of fused α‐oligothiophene units as building blocks, end‐capped with either styrene or 1‐pentyl‐4‐vinylbenzene groups, has been synthesized through Stille coupling reactions. The compounds have been fully characterized by means of 1H NMR spectrometry, high‐resolution mass spectrometry, and elemental analysis. The molecules present a trans–trans configuration between their double bonds, which has been verified and confirmed by Fourier‐transform infrared spectroscopy and single‐crystal X‐ray diffraction analysis. The X‐ray crystal structures showed π–π overlap and sulfur–sulfur interactions between the adjacent molecules. The decomposition temperatures were all found to be above 300 °C, indicating that compounds of this series possess excellent thermal stability. The fact that no phase transition occurs at low temperature indicates that they should be well‐suited for application in devices. Moreover, they possess low HOMO energy levels, based on cyclic voltammetry measurements, and suitable energy gaps, as determined from their thin‐film UV/Vis spectra. Thin‐film X‐ray diffraction analysis and atomic force microscopy revealed high crystallinity on supporting substrates. In addition, as the substrate temperature has a significant influence on the morphology and the degree of crystallinity, the device performance could be optimized by varying the substrate temperature. These materials were found to exhibit optimal field‐effect performance, with a mobility of 0.17 cm2 V?1 s?1 and an on/off ratio of 105, at a substrate temperature of 70 °C. |
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Keywords: | device performance organic field‐effect transistors semiconductors sulfur heterocycles |
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