nn7b03954_si_001.pdf (3.66 MB)
Donor–Acceptor Properties of a Single-Molecule Altered by On-Surface Complex Formation
journal contribution
posted on 2017-07-21, 00:00 authored by Tobias Meier, Rémy Pawlak, Shigeki Kawai, Yan Geng, Xunshan Liu, Silvio Decurtins, Prokop Hapala, Alexis Baratoff, Shi-Xia Liu, Pavel Jelínek, Ernst Meyer, Thilo GlatzelElectron donor–acceptor molecules
are of outstanding interest in molecular electronics and organic solar
cells for their intramolecular charge transfer controlled via electrical or optical excitation. The preservation of
their electronic character in the ground state upon adsorption on
a surface is cardinal for their implementation in such single-molecule
devices. Here, we investigate by atomic force microscopy and scanning
tunneling microscopy a prototypical system consisting of a π-conjugated
tetrathiafulvalene-fused dipyridophenazine molecule adsorbed on thin
NaCl films on Cu(111). Depending on the adsorption site, the molecule
is found either in a nearly undisturbed free state or in a bound state.
In the latter case, the molecule adopts a specific adsorption site,
leading to the formation of a chelate complex with a single Na+ alkali cation pulled out from the insulating film. Although
expected to be electronically decoupled, the charge distribution of
the complex is drastically modified, leading to the loss of the intrinsic
donor–acceptor character. The chelate complex formation is
reversible with respect to lateral manipulations, enabling tunable
donor–acceptor molecular switches activated by on-surface coordination.