Density Functional Theoretical Study of Perfluoropentacene/Noble Metal Interfaces with van der Waals Corrections: Adsorption States and Vacuum Level Shifts

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• 作者：Kenji Toyoda ; Ikutaro Hamada ; Kyuho Lee ; Susumu Yanagisawa ; Yoshitada Morikawa
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：April 7, 2011
• 年：2011
• 卷：115
• 期：13
• 页码：5767-5772
• 全文大小：860K
• 年卷期：v.115,no.13(April 7, 2011)
• ISSN：1932-7455

文摘

We have studied the electronic structures of perfluoropentacene (PFP) on Cu(111), Ag(111), and Au(111) by means of density functional theory with a semiempirical van der Waals method (DFT-D). We show that DFT-D yields accurate equilibrium PFP-metal distances, thereby making an accurate prediction of the work-function change (螖) possible. In order to investigate the nature of the interface dipole layer, we calculated 螖 as a function of PFP-substrate distance and found that in contrast to pentacene/metal interfaces, the molecular distortion has a significant influence on 螖 at a short distance. However, by subtracting the contribution of the molecular distortion from the total work-function change, we show that the work-function change does not depend on the substrate work-function at a long distance, while the work-function change varies linearly with the substrate work-function at a short distance. Our results indicate a transition from Schottky to Bardeen limits as a PFP molecule approaches the substrate metal surface, as in pentacene/metal interfaces.