Towards increasing the photon harvesting in bulk heterojunction polymer solar cells.:Electrochemical, Radiational, and Thermal Energy Technology

Org. solar cells based on interpenetrating networks of conjugated polymer donors and fullerene-based acceptors with MA 1.5 efficiencies up to 3% were presented recently. For further improvement of the efficiency, the absorption of the solar light should be increased. This can be done by matching the active layer absorption better to the terrestrial solar emission spectrum and by increasing the absorption coeff. In this contribution the authors present a combined spectroscopic and device study of novel materials that extend the absorption to the red. The systems studied are, among others, low bandgap polymers as electron donors or dye sensitized fullerene compds. The photophys. properties are studied by excited state spectroscopy and the materials are discussed with regard to their suitability for efficient photoinduced charge generation. The photovoltaic activity is demonstrated by photocurrent action spectra as well as by AM 1.5 efficiencies of prototype devices made using these novel materials. [on SciFinder(R)