Π Band Dispersion along Conjugated Organic Nanowires Synthesized on a Metal Oxide Semiconductor

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• 作者：Guillaume Vasseur ; Mikel Abadia ; Luis A. Miccio ; Jens Brede ; Aran Garcia-Lekue ; Dimas G. de Oteyza ; Celia Rogero ; Jorge Lobo-Checa ; J. Enrique Ortega
• 刊名：Journal of the American Chemical Society
• 出版年：2016
• 出版时间：May 4, 2016
• 年：2016
• 卷：138
• 期：17
• 页码：5685-5692
• 全文大小：544K
• 年卷期：0
• ISSN：1520-5126

文摘

Surface-confined dehalogenation reactions are versatile bottom-up approaches for the synthesis of carbon-based nanostructures with predefined chemical properties. However, for devices generally requiring low-conductivity substrates, potential applications are so far severely hampered by the necessity of a metallic surface to catalyze the reactions. In this work we report the synthesis of ordered arrays of poly(p-phenylene) chains on the surface of semiconducting TiO₂(110) via a dehalogenative homocoupling of 4,4″-dibromoterphenyl precursors. The supramolecular phase is clearly distinguished from the polymeric one using low-energy electron diffraction and scanning tunneling microscopy as the substrate temperature used for deposition is varied. X-ray photoelectron spectroscopy of C 1s and Br 3d core levels traces the temperature of the onset of dehalogenation to around 475 K. Moreover, angle-resolved photoemission spectroscopy and tight-binding calculations identify a highly dispersive band characteristic of a substantial overlap between the precursor’s π states along the polymer, considered as the fingerprint of a successful polymerization. Thus, these results establish the first spectroscopic evidence that atomically precise carbon-based nanostructures can readily be synthesized on top of a transition-metal oxide surface, opening the prospect for the bottom-up production of novel molecule–semiconductor devices.