Doped conducting-polymer–semiconducting-polymer interfaces: Their use in organic photovoltaic devices

We report a study of the interface between poly(p-phenylene vinylene) (PPV) and poly(ethylene dioxythiophene) doped with polystyrene sulfonic acid (PEDOT:PSS). We find from measurements of optical absorption and conductivity that PSS dopes PPV during the sample preparation. In addition, the photoluminescence efficiency of PPV is strongly affected by the presence of PSS which we attribute to the effect of chemical doping. We further studied the interaction between PSS and PPV by measurements of the photovoltaic response, spectrally resolved, of a number of diode structures. By forming the interface between a layer of PEDOT:PSS and a layer of PPV precursor prior to the thermal conversion we obtained an interpenetrating interface with large surface area between the photoresponsive and the charge collecting polymers. For devices made with PEDOT:PSS as top electrode and aluminum as the bottom electrode the short-circuit external quantum efficiency is 4%.