Photovoltaic devices from fullerene--oligophenyleneethynylene conjugates.

Abstract

Exploitation of the particular electronic properties of fullerenes for solar energy conversion has become a field of intensive investigation. The modification of semiconductor or metal electrodes with fullerene thin films has revealed promising photoelectrochemical properties. Good solar energy conversion efficiencies have also been obtained with sandwich-type conjugated polymer/fullerene heterojunctions. As part of this research, we have recently shown that fullerene derivatives, in which an oligophenylenevinylene (OPV) group is attached to C60, can be incorporated into photovoltaic cells. This molecular approach for solar energy conversion appears to be particularly interesting, since the bicontinuous network obtained by chemically linking the hole-conducting OPV moiety to the electron-conducting fullerene subunit prevents any problems arising from bad contacts at the junction, as observed for polymer/C60 blends. Furthermore, this new synthetic approach also offers great versatility for designed tuning of the photovoltaic system. We now report the preparation of plastic solar cells from fullerene ±oligophenyleneethynylene (OPE) derivatives 1 ±4. For compounds 1 and 2, the efficiencies of the resulting photovoltaic devices are similar to those prepared from corresponding fullerene ±OPV conjugates. Interestingly, by increasing the donating ability of the