From Pinwheels to Quasicrystals: Investigations of C60 and Pentacene via Scanning Tunneling Microscopy
C60 and pentacene are archetypal molecules for the study of adsorption at surfaces due to their simple structures. Due to their strong optical absorption and complementary organic semiconductor properties, they are also used in the active layers of bulk heterojunction solar cells.
In this talk I will describe how we can construct heterojunctions inside the scanning tunneling microscope tunnel junction from single layers of these molecules, and how they perform as diodes. When adsorbed on a Cu(111) surface in a mixed molecular layer, strong interactions between the molecules lead to the formation of supramolecular chiral pinwheel structures, which again show charge transfer between the molecules in a manner consistent with a picture of the pinwheel as a heterojunction.
Finally, I will describe how these molecules can be induced to form extended two-dimensional quasicrystalline networks, when adsorption is templated by using quasicrystalline substrates.
(1) Smerdon, J. A.; Rankin, R. B.; Greeley, J. P.; Guisinger, N. P.; Guest, J. R. Chiral “Pinwheel” Heterojunctions Self-Assembled from C60 and Pentacene. ACS Nano 2013, 7, 3086–3094.
(2) Smerdon, J. A.; Giebink, N. C..; Guisinger, N. P.; Guest, J. R. Reversible rectifying donor-acceptor molecular heterojunctions at the single molecule limit. In preparation 2013.
(3) Smerdon, J. A.; Young, K. Y.; Lowe, M.; Sharma, H. R.; Hesp, D.; Dhanak, V. R.; McGrath, R. Extended two-dimensional molecular quasicrystals. In preparation 2013.