Dispersive Electronic States of the π-Orbitals Stacking in Single Molecular Lines on the Si(001)-(2×1)-H Surface.

Abstract

One-dimensional (1D) molecular assemblies have been considered as one of the potential candidates for miniaturized electronic circuits in organic electronics. Here, we present the quantitative experimental measurements of the dispersive electronic feature of 1D benzophenone molecular assemblies on the Si(001)-(2×1)-H. The well-aligned molecular lines and their certain electronic state dispersion were observed by scanning tunneling microscopy (STM) and angle-resolved ultraviolet photoemission spectroscopy (ARUPS), respectively. Density functional theory (DFT) calculations reproduced not only the experimental STM image but also the dispersive features that originated from the stacking phenyl π-orbitals in the molecular assembly. We obtained the effective mass of 2.0me for the hole carrier along the dispersive electronic state, which was comparable to those of the single-crystal molecules widely used in organic electronic applications. These results ensure the one-dimensionally delocalized electronic states in the molecular lines, which is requisitely demanded for a charge-transport wire.