Π Band Dispersion along Conjugated Organic Nanowires Synthesized on a Metal Oxide Semiconductor.
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.
Centro de Física de Materiales (Consejo Superior de Investigaciones Científicas (CSIC)/Universidad del País Vasco (UPV)-Euskal Herriko Unibertsitatea (EHU)-Materials Physics Center (MPC) , Paseo Manuel Lardizabal 5, 20018 San Sebastián, Spain.|Donostia International Physics Center (DIPC) , Paseo Manuel Lardizabal 4, 20018 San Sebastián, Spain.
Guillaume
G
Vasseur
Centro de Física de Materiales (Consejo Superior de Investigaciones Científicas (CSIC)/Universidad del País Vasco (UPV)-Euskal Herriko Unibertsitatea (EHU)-Materials Physics Center (MPC) , Paseo Manuel Lardizabal 5, 20018 San Sebastián, Spain.
Mikel
M
Abadia
Centro de Física de Materiales (Consejo Superior de Investigaciones Científicas (CSIC)/Universidad del País Vasco (UPV)-Euskal Herriko Unibertsitatea (EHU)-Materials Physics Center (MPC) , Paseo Manuel Lardizabal 5, 20018 San Sebastián, Spain.|Donostia International Physics Center (DIPC) , Paseo Manuel Lardizabal 4, 20018 San Sebastián, Spain.
Luis A
LA
Miccio
Centro de Física de Materiales (Consejo Superior de Investigaciones Científicas (CSIC)/Universidad del País Vasco (UPV)-Euskal Herriko Unibertsitatea (EHU)-Materials Physics Center (MPC) , Paseo Manuel Lardizabal 5, 20018 San Sebastián, Spain.|Donostia International Physics Center (DIPC) , Paseo Manuel Lardizabal 4, 20018 San Sebastián, Spain.
Jens
J
Brede
Donostia International Physics Center (DIPC) , Paseo Manuel Lardizabal 4, 20018 San Sebastián, Spain.|Ikerbasque, Basque Foundation for Science , 48011 Bilbao, Spain.
Aran
A
Garcia-Lekue
Centro de Física de Materiales (Consejo Superior de Investigaciones Científicas (CSIC)/Universidad del País Vasco (UPV)-Euskal Herriko Unibertsitatea (EHU)-Materials Physics Center (MPC) , Paseo Manuel Lardizabal 5, 20018 San Sebastián, Spain.|Donostia International Physics Center (DIPC) , Paseo Manuel Lardizabal 4, 20018 San Sebastián, Spain.|Ikerbasque, Basque Foundation for Science , 48011 Bilbao, Spain.
Dimas G
DG
de Oteyza
Centro de Física de Materiales (Consejo Superior de Investigaciones Científicas (CSIC)/Universidad del País Vasco (UPV)-Euskal Herriko Unibertsitatea (EHU)-Materials Physics Center (MPC) , Paseo Manuel Lardizabal 5, 20018 San Sebastián, Spain.|Donostia International Physics Center (DIPC) , Paseo Manuel Lardizabal 4, 20018 San Sebastián, Spain.
Celia
C
Rogero
Centro de Física de Materiales (Consejo Superior de Investigaciones Científicas (CSIC)/Universidad del País Vasco (UPV)-Euskal Herriko Unibertsitatea (EHU)-Materials Physics Center (MPC) , Paseo Manuel Lardizabal 5, 20018 San Sebastián, Spain.|Instituto de Ciencia de Materiales de Aragón (ICMA), CSIC-Universidad de Zaragoza , 50009 Zaragoza, Spain.|Departamento de Física de la Materia Condensada, Universidad de Zaragoza , 50009 Zaragoza, Spain.
Jorge
J
Lobo-Checa
Centro de Física de Materiales (Consejo Superior de Investigaciones Científicas (CSIC)/Universidad del País Vasco (UPV)-Euskal Herriko Unibertsitatea (EHU)-Materials Physics Center (MPC) , Paseo Manuel Lardizabal 5, 20018 San Sebastián, Spain.|Donostia International Physics Center (DIPC) , Paseo Manuel Lardizabal 4, 20018 San Sebastián, Spain.|Departamento Física Aplicada I, Universidad del País Vasco , 20018 San Sebastián, Spain.
J Enrique
JE
Ortega