Realization of Large Area Flexible Fullerene - Conjugated Polymer Photocells: A Route to Plastic Solar Cells

摘要

Various interesting photophysical phenomena in composites of fullerenes and non degenerate ground state conjugated polymers with highly extended π-electrons in their main chain can be explained by the ultrafast electron transfer from the conjugated polymer (donor) to the fullerene (acceptor) upon illumination. This photoeffect was utilized for the production of small area (mm~2) photovoltaic devices which show energy conversion efficiencies η_e > 1% and carrier collection efficiencies η_c > 20%. In this work we present efficiency and stability studies on large area (6 cm by 6 cm) flexible solar cells based on a soluble alkoxy PPV (3,7 -dimethyloctyloxy methyloxy poly(phenylenevinylene)) and a highly soluble fullerene derivative, l-(3-methoxycarbonyl)propyl-lphenyl [5,6]C_(61) (PCBM). The enhanced solubility of PCBM compared to C_(60) allows a high fullerene - conjugated polymer ratio and strongly supports the formation of donor - acceptor bulk heterojunctions.