Influence of chemical doping on the performance of organic photovoltaic cells

The power conversion efficiency of organic photovoltaic cells can be greatly enhanced by chemical doping to control the conductivity of the organic thin films. We demonstrate a nearly twofold improvement in the efficiency of planar heterojunction copper phthalocyanine/fullerene cells by n-doping the electron acceptor layer with decamethylcobaltocene in the vicinity of the fullerene/cathode interface. Doping improves the charge extraction efficiency and decreases the series resistance of the organic films, improving the current density and fill factor, respectively.