Date/Time: 04-24-2019 - Wednesday - 05:00 PM - 07:00 PM
Alice Smith1 Donal Bradley1 2

1, University of Oxford, Oxford, , United Kingdom
2, University of Oxford, Oxford, , United Kingdom

Patterning structures at the scale of the wavelength of light is central to photonic device fabrication. Whilst standard patterning techniques such as e-beam lithography can be used to pattern the topography of many materials, orientation, configuration and conformation can also be used to control the optical properties of molecular materials. An example of conformation control is formation of the β-phase in the organic semiconductor poly(9,9-dioctylfluorene) (PFO), in which polymer chain segments adopt a rigid, planar structure when subjected to particular solvent interactions. The photophysics of this phase has been studied in great detail, with particular focus on the presence of a new long wavelength absorption peak, which results in a significant change in refractive index within the optical gap (10.9% at 450nm). The index change offers potential for photonic element fabrication, in a fashion that mimics dielectric metamaterial structuring on a molecular length scale. Spatial patterning of the structure defines the photonic elements, with millimeter scale patterning shown in 2009, followed by micron scale in 2012, and nanoscale in 2015. We now report a further study on the use of Dip Pen Nanolithography (DPN) - an AFM derived single step writing process - as a technique to pattern nanoscale structures and discuss their suitability for photonic device applications.

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