Abstract
An ordered copper-phthalocyanine (CuPc) single layer deposited on the Au(110) surface has been electron-doped by exposition to potassium. Progressive occupation of the former lowest unoccupied molecular orbitals (LUMOs) up to the filling of the twofold degenerate LUMO and and levels, has been detected by near-edge x-ray absorption spectroscopy spectra. The electronic states filled by electron transfer from the alkali atoms are localized at the interface, and the process induces a redistribution of the density of states with a conspicuous decrease in spectral density at the Fermi level. Localization of the final states, sudden decrease in density of states at the Fermi level, minor screening of the electron-hole excitations, and enhanced excitonic effects of doped CuPc with respect to the pristine CuPc single-layer concur to suggest that the electron injection produces a Mott insulator where correlation effects dominate the electronic properties.
1 More- Received 12 January 2009
DOI:https://doi.org/10.1103/PhysRevB.79.115446
©2009 American Physical Society