Control of Two-Dimensional Ordering of F16CuPc on Bi/Ag(111): Effect of Interfacial Interactions

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• 作者：Kelvin Hong Liang Zhang ; Hui Li ; Hongying Mao ; Han Huang ; Jing Ma ; Andrew Thye Shen Wee ; Wei Chen
• 刊名：Journal of Physical Chemistry C
• 出版年：2010
• 出版时间：July 1, 2010
• 年：2010
• 卷：114
• 期：25
• 页码：11234-11241
• 全文大小：574K
• 年卷期：v.114,no.25(July 1, 2010)
• ISSN：1932-7455

文摘

In-situ low-temperature scanning tunneling microscopy, density functional theory (DFT) calculations, and molecular dynamics (MD) simulations have been used to systematically investigate the supramolecular assembly of copper hexadecafluorophthalocyanine (F₁₆CuPc) on various Bi/Ag(111) surfaces, including metallic BiAg₂ surface alloy, semimetal Bi-P × √3 overlayer and Bi(110) monolayer. We demonstrate that the molecular ordering of F₁₆CuPc is strongly affected by the molecule−substrate interfacial interactions on different substrates and the intermolecular interactions. At the monolayer region (l^st layer), F₁₆CuPc molecules interact strongly with BiAg₂ and form a quasi-hexagonal unit cell with two alternative “α” and “β” in-plane orientations to minimize the repulsive electrostatic forces between neighboring F₁₆CuPc. In contrast, a highly ordered quadratic monolayer structure with the same in-plane orientation forms on both P × √3 overlayer and Bi(110) surface due to the relatively weak interfacial interactions. The molecular ordering in the second layer is largely governed by the delicate balance between the interlayer π−π interaction between the first two layers and the intermolecular interaction within the second layer. To reduce the electrostatic repulsion resulting from the fluorine atoms, the second layer F₁₆CuPc adopts either a rotated or slipped geometry with respect to the first layer. It is also found that the second layer F₁₆CuPc always adopts a 4-fold symmetry lattice regardless of the underlying substrates, consistent with our MD simulations. DFT calculations also demonstrate that for the second layer of F₁₆CuPc molecules, the rotated geometry is the most favorable.