Mesoscale optical properties of conjugated polymers probed by near-field scanning optical microscopy

Near-field scanning optical microscopy (NSOM) has been used to study the mesoscale optical properties of oriented and non-oriented free-standing thin films of poly(p-phenylene vinylene) (PPV). We report a strong correlation between film morphology and the optical properties on a 100 nm scale. The non-oriented PPV thin film exhibits mesoscale domains of local molecular orientation as well as areas which are characterized by a low photoluminescence efficiency. Upon stretch orientation, PPV thin films show average polymer chain orientation parallel to the stretch axis as well as distinct areas of perpendicular molecular orientation correlated to film topography.