Engineering specific interactions in polymers,
such as “face-to-face” or “head-to-tail” interactions, is central
to advancing polymer-based optoelectronics. Barnes, Hayward and Emrick, working
collaboratively in the Materials Research Science and Engineering Center on
Polymers at UMass, showed that crystalline 2-D “nanowires” of conjugated polymers
exhibit both types of interactions. Using single-molecule spectroscopy
techniques, isolated nanowires were imaged and probed spectroscopically to
reveal distinct spectral signatures of both J-type (head-to-tail), and
H-type (face-to-face) electronic interactions.
Controlling the directionality of such interactions is important for
directing charge- and energy flow in solar cells and related devices.