Dip-pen patterning of poly(9,9-dioctylfluorene) chain-conformation-based nano-photonic elements

Aleksandr Perevedentsev, Yannick Sonnefraud, Colin R. Belton, Sanjiv Sharma, Anthony E. G. Cass, Stefan A. Maier, Ji-Seon Kim, Paul N. Stavrinou, Donal D. C. Bradley

Metamaterials are a promising new class of materials, in which sub-wavelength physical structures, rather than variations in chemical composition, can be used to modify the nature of their interaction with electromagnetic radiation. Here we show that a metamaterials approach, using a discrete physical geometry (conformation) of the segments of a polymer chain as the vector for a substantial refractive index change, can be used to enable visible wavelength, conjugated polymer photonic elements. In particular, we demonstrate that a novel form of dip-pen nanolithography provides an effective means to pattern the so-called β-phase conformation in poly(9,9-dioctylfluorene) thin films. This can be done on length scales ≤500 nm, as required to fabricate a variety of such elements, two of which are theoretically modelled using complex photonic dispersion calculations.