Near-field photoconductivity of stretch-oriented poly(para-phenylene vinylene)

Near-field scanning optical microscopy (NSOM) with photoconductivity contra st is used to map the transport properties of stretch-oriented poly(p-pheny lene vinylene) thin films on a 150 nm length scale. Near-field photoconduct ivity is highly sensitive to film morphology and contrast is observed even in films with uniform photoluminescence. Regions of relatively higher photo current signals are correlated to regions with higher molecular order which have contrast approaching 15%. In addition, the photocurrent signal decrea ses sharply as the near-field tip approaches the surface of the film while at the same time the photoluminescence signal increases. The sharp decrease is attributed to the perturbation of the applied electric field within the polymer film by the metal on the NSOM tip. (C) 1999 American Institute of Physics. [S0003-6951(99)04248-5].