The photovoltaic effect in a poly(p-phenylenevinylene)/perylene heterojunction

We have measured the photovoltaic properties of heterojunctions consisting of a layer of the molecular pigment bis(phenethylimido)perylene, sublimed onto a film of the conjugated polymer poly(p-phenylenevinylene) [PPV], sandwiched between electrodes of indium tin oxide (ITO) and aluminium. Quantum yields (electrons collected per incident photon) of up to 6%, fill factors of 0.6 and open-circuit voltages approaching 1 V were obtained, representing significant improvements over single-layer PPV devices. We interpret the photoresponse as arising from the efficient dissociation of electrons and holes at the PPV/perylene interface. Application of a simple model to the photocurrent action spectra yields an estimate of the exciton diffusion range of 90+/-10 Angstrom.