Bipolar phototransport in π-conjugated polymer/C60 composites

Conjugated polymer/fullerene composite films that exhibit steady-state phototransport properties of a unipolar or bipolar photoconductor, depending on the relative concentration of the components, are described. The observed behavior of the composites, in which each component has its own percolation path but its carrier content is not high enough to quench the carriers in the other component, is shown to be due to the coupling of the recombination processes in the two components. (C) 2001 American Institute of Physics.