Near-Field Scanning Optical Lithography for Nanostructuring Electroactive Polymers

The photochemistry of poly{p-phenylene[1-(tetrahydrothiophen-1-io)ethylene chloride]} (PPTEC), a water soluble precursor of the semiconducting polymer, poly{p-phenylenevinylene} (PPV), has been studied both under atmospheric conditions and in environments devoid of oxygen. UV-visible spectroscopy and photoluminescence data has been used to provide a picture of the mechanistic pathways involved in UV irradiation of the PPTEC material. A new quantitative model for the effect of UV irradiation upon film morphology is presented. The technique of near-field scanning optical lithography (NSOL) has been used to produce arbitrary structures of the semi-conducting polymer poly{p-phenylenevinylene} at sizes comparable with optical wavelengths. Structures on this scale are of interest for integrated optical devices and organic solar cells. The structures are characterised using AFM and SEM and examined in the context of the electric field distribution at the NSOM tip. The Bethe-Bouwkamp model for electric field distribution at an aperture has been used, in combination with the developed model for precursor solubility dependence on UV energy dose, to predict the characteristics of lithographic features produced by NSOL. Fine structure in the lithographic features that are characteristic of the technique are investigated and their origins explained. Suggestions for the improvement of the technique are made. Presented here for the first time is a device manufactured by the technique of NSOL functioning as an optical device. The technique of NSOL is used to manufacture an optical transmission phase grating (or phase mask) of PPV, this was done as a proof of concept for device manufacture by this method and to demonstrate the potential usefulness of the unique characteristics of the technique. The phase mask was characterised using AFM and SEM and examined in the context of how well a diffraction pattern matches with theoretical calculations.