Nanoscale oxidative patterning and manipulation of conjugated polymer thinfilms

Near-field scanning optical microscopy (NSOM) is used to modify the surface of thin films of poly[2-methoxy,5-(2'-ethylhexoxy)-1,4-phenylenevinylene] (MEH-PPV) with spatial resolution of 100 nm. Thin films were patterned usin g the NSOM tip with high power illumination (approaching 1 kW/cm(2)). This exposure results in both a reduction of the photoluminescence of the film a nd a change in the surface topography (a surface depression). By monitoring the broadening of the emission spectrum as a function of exposure time in ambient conditions and under flowing nitrogen, we confirm that the pattern is due to photo-oxidation, We have thoroughly examined the dependence of th e depth of contrast, the size of the dark spot and the size of the surface depression on illumination power, energy migration and exposure time. In ad dition, we have created a number of patterns with features limited only by the size of the NSOM tip.