The Optical and Charge Transport Properties of Discotic Materials with Large Aromatic Hydrocarbon Cores

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• 作者：Michael G. Debije ; Jorge Piris ; Matthijs P. de Haas ; John M. Warman ; g src="http ; //pubs.acs.org/images/entities/Zcaron.gif" border="0">eljko Tomovig src="http ; //pubs.acs.org/images/entities/cacu
• 刊名：Journal of the American Chemical Society
• 出版年：2004
• 出版时间：April 14, 2004
• 年：2004
• 卷：126
• 期：14
• 页码：4641 - 4645
• 全文大小：108K
• 年卷期：v.126,no.14(April 14, 2004)
• ISSN：1520-5126

文摘

The optical absorption and charge transport properties of a series of discotic molecules consistingof peripherally alkyl-substituted polycyclic aromatic cores have been investigated for core sizes, n, of 24,42, 60, 78, 96, and 132 carbon atoms. In dilute solution, the wavelength maximum of the first absorptionband increases linearly with n according to ges/gifchars/lambda.gif" BORDER=0 >_max = 280 + 2n and the spectral features become increasinglybroadened. The two smallest core compounds display a slight red-shift and increased spectral broadeningin spin-coated films. For derivatives with n = 24, 42, 60, and 96, the one-dimensional, intracolumnar chargemobility, ges/gifchars/Sigma.gif" BORDER=0 >ges/entities/mgr.gif">_1D, was determined using the pulse-radiolysis time-resolved microwave conductivity technique.For the compounds which were crystalline solids at room temperature, ges/gifchars/Sigma.gif" BORDER=0 >ges/entities/mgr.gif">_1D lay within the range 0.4-1.0cm²/Vs. In the discotic mesophases at ca. 100 ges/entities/deg.gif">C, ges/gifchars/Sigma.gif" BORDER=0 >ges/entities/mgr.gif">_1D was somewhat lower and varied from 0.08 to 0.38cm²/Vs. The mobility values in both phases are considerably larger than the maximum values foundpreviously for discotic triphenylene derivatives. However, the recently proposed trend toward increasingmobility with increasing core size is not substantiated by the results on the present series of increasinglylarge aromatic core compounds.