| Title | Orbital Redistribution in Molecular Nanostructures Mediated by Metal-Organic Bonds |
| Authors | Zechao Yang, Martina Corso, Roberto Robles, Christian Lotze, Roland Fitzner, Elena Mena-Osteritz, Peter Bäuerle, Katharina J Franke, and Jose I. Pascual |
| Journal | ACS Nano |
| Vol. 8, 2014, pg. 10715 |
| Abstract | Dicyanovinyl-quinquethiophene (DCV5T-Me2) is a prototype conjugated oligomer for highly effcient organic solar cells. This class of oligothiophenes are built up by an electron-rich donor (D) backbone and terminal electron-defcient acceptor (A) moieties. Here, we investigated its structural and electronic properties when it is adsorbed on a Au(111) surface using low temperature scanning tunneling microscopy/spectroscopy (STM/STS) and atomic force microscopy (AFM). We fnd that DCV5T-Me2 self-assembles in extended chains, stabilized by intercalated Au atoms. The e ect of metal-ligand hybridization with Au adatoms causes an energetic downshift of the DCV5T-Me2 lowest unoccupied molecular orbital (LUMO) with respect to the uncoordinated molecules on the surface. The asymmetric coordination of a gold atom to only one molecular endgroup leads to an asymmetric localization of the LUMO and LUMO+1 states at opposite sides. Using model density functional theory (DFT) calculations, we explain such orbital reshaping as a consequence of linear combinations of the original LUMO and LUMO+1 orbitals, mixed by the attachment of a bridging Au adatom. Our study shows that the alignment of molecular orbitals and their distribution within individual molecules can be modi ed by contacting them to metal atoms in specific sites. |
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