| Title | Optically Reconfigurable Monolayer of Azobenzene Donor Molecules on Oxide Surfaces |
| Author | Kyle M. McElhinny†, Peishen Huang†, Yongho Joo†, Catherine Kanimozhi†, Arunee Lakkham†, Kenji Sakurai‡§, Paul G. Evans*†, and Padma Gopalan*† |
| Affiliation(s) | † Department of Materials Science and Engineering, University of Wisconsin−Madison, Madison, Wisconsin 53706, United States
‡ National Institute for Materials Science, Tsukuba, Ibaraki 305-4007, Japan
§ University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan |
| Published | Langmuir, 2017, 33 (9), pp 2157–2168 DOI: 10.1021/acs.langmuir.6b04585 |
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| Abstract | The structural configuration of molecules assembled at organic–inorganic interfaces within electronic materials strongly influences the functional electronic and vibrational properties relevant to applications ranging from energy storage to photovoltaics. Controlling and characterizing the structural state of an interface and its evolution under external stimuli is crucial both for the fundamental understanding of the factors influenced by molecular structure and for the development of methods for material synthesis. It has been challenging to create complete molecular monolayers that exhibit external reversible control of the structure and electronic configuration. We report a monolayer/inorganic interface consisting of an organic monolayer assembled on an oxide surface, exhibiting structural and electronic reconfiguration under ultraviolet illumination. The molecular monolayer is linked to the surface through a carboxylate link, with the backbone bearing an azobenzene functional group and the head group consisting of a rhenium–bipyridine group. Optical spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy, and X-ray reflectivity show that closely packed monolayers are formed from these molecules via the Langmuir–Blodgett technique. Reversible photoisomerization is observed in solution and in monolayers assembled on Si and quartz substrates. The reconfiguration of these monolayers provides additional means to control excitation and charge transfer processes that are important in applications in catalysis, molecular electronics, and solar energy conversion. |
