Screening for artifacts in near-field scanning photocurrent microscopy images of polymer solar cells

We present the results of an investigation to screen for the presence of artifacts in near-field scanning photocurrent microscopy (NSPM) images of polymer solar cells caused by variations in tip-sample separation. We show that by increasing the size of the probe tip we are able to deliberately degrade the surface topographical image without altering the photocurrent image. This work demonstrates that NSPM images of polymer solar cells reliably probe the local charge generation properties of the device and are not significantly influenced by the presence of artifacts. Polyfluorene blend solar cells are used as a model system for this study.