Effects of Perfluorination on Thiophene and Pyrrole Oligomers

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• 作者：Ulrike Salzner
• 刊名：Journal of Physical Chemistry A
• 出版年：2010
• 出版时间：April 29, 2010
• 年：2010
• 卷：114
• 期：16
• 页码：5397-5405
• 全文大小：367K
• 年卷期：v.114,no.16(April 29, 2010)
• ISSN：1520-5215

文摘

The effect of perfluorination on thiophene and pyrrole oligomers in neutral, cationic, and anionic states was investigated with density functional theory at the (TD)B3P86-30%/6-31G* level. For the title compounds fluorination leads to planarization. For pyrroles a band gap reduction of 0.58 eV results, as unsubstituted pyrroles are nonplanar and disordered in the solid state. For thiophene the band gap is slightly increased as long thiophene oligomers are almost planar. Ionization energies and electron affinities increase upon fluorination by 0.65 and 0.60 eV for polythiophene and by 0.45 and 0.90 eV for polypyrrole. Conduction band widths increase by 0.5 for polythiophene and by 0.7 eV for polypyrrole. Spectra of charged (doped) forms are almost identical to those of the parent systems. Like parent systems, fluorinated oligomers with chain lengths of more than six rings develop a third UV absorption that increases in strength and decreases in energy upon chain length increase.