| Apr 10, 2013 |
Chiral 'pinwheels' self-assembled from C60 and pentacene
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(Nanowerk News) In a recent study ("
Chiral “Pinwheel” Heterojunctions Self-Assembled from C60 and Pentacene") from the Electronic & Magnetic Materials & Devices and Theory & Modeling groups, C60 and pentacene (Pn) molecules, two workhorses of organic electronics and opto-electronics, are observed to self-assemble on a Cu(111) surface into in-plane "pinwheel"-shaped and chiral heterojunctions.
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| UHV STM image of C60-Pn in-plane chiral heterojunctions, overlaid with molecular models showing the orientation and the chirality (right-handed green, left-handed blue) (middle).
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Calculations confirm that the heterostructures are energetically favorable conformations and reveal electron charge transfer from the Pn to the C60 in this chiral morphology, a critical signature of electronic heterojunctions.
The demonstration that these highly symmetric acceptor and donor molecules, which are widely used in organic electronics and photovoltaics, form chiral structures suggests a potential path to integrating chiral selectivity with optical absorption and charge separation, even with highly symmetric achiral molecules.
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| Calculated map of the electron density changes due to the heterojunction showing electron transfer to the C60 in the center.
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Studies in an ultrahigh vacuum (UHV) system with surface preparation and scanning tunneling microscopy (STM) capabilities were critical to characterizing the self-assembled systems at the atomic scale in an ultraclean environment. In addition, the computing cluster "Carbon" supported density functional theory calculations with van der Waals corrections on these complex structures.
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