Getting single molecules of semiconducting polymers to orient themselves vertically on a glass surface is more than just a novelty, says Mike Barnes of the lab's Chemical Sciences Division. It turns out that the discovery could have applications in a number of areas, including for nanoscale electronics, polymer-based light emitting diodes and nano-scale sensors. Barnes and colleagues used ink-jet printing techniques to isolate the single molecules and achieve an extraordinary degree of orientational uniformity and intramolecular organization. "What's remarkable is that the orientation is in the non-intuitive z direction, like pencils all standing on their erasers instead of lying flat," Barnes said. As a result, they have photophysical properties that are quite different than similar molecules oriented randomly in thin films. For example, oriented single molecules emit light that lasts for several hours instead of just a few minutes, which is typical of randomly oriented single molecules of semiconducting polymers. This may have important implications in enhancing polymer-based optoelectronic device performance. The work has been published in Nanoletters and a paper is scheduled to appear in a June letter to the editor in Journal of Physical Chemistry B.
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