The mechanisms of charge generation, transport and recombination are up to date not fully understood [1]. This is of great importance for applications such as nanoelectronics, solar cells, etc. The C60-phthalocyanine complex is a promising candidate for charge transfer, since the C60 molecules act as electron acceptors, while the phthalocyanine molecules show electron donor character. [3] The adsorption of such complexes on the noble metal surfaces [2] is hence of great interest for studying such phenomena.
The study of such molecular complexes on the three (111) noble metal surfaces was performed by means of Scanning Tunneling Microscopy technique. The deposition of phthalocyanine derivates (consisting of eight ditertiarybutylphenyl substituents attached over an oxygen atom to the peripheral phenyl rings) by thermal evaporation results into different ordering on the substrate depending on the central atom of the derivate. The subsequent deposition of C60 onto the phthalocyanine layer revealed two different, clearly distinguishable binding sites - in the center of a phthalocyanine derivate or in between two adjacent molecules, hence enabling the investigation of both, central and peripheral non-covalent C60 bonding, individually. Moreover, altering the central part of the phthalocyanine derivate resulted in changes of the bond strength, as observed by the change of the onset temperature at which the centrally bonded C60 molecules begin to move.
[1] C. Pannemann, V. Dyakonov, J. Parisi, O. Hild, D. Wohrle Synthetic Metals, 121, 1, 1585 2001
[2] M. Stöhr, T. Wagner, M. Gabriel, B. Weyers, and R. Möller, Phys. Rev. B 65, 033404 2001
[3] Y. Zhao, L. Gan, D. Zhou, C.-H. Huang, J. Jiang, W. Liu, Solid State Commun. 106, 43 1998
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