Loading Fullerene into a Conjugated Polymer Without Chemical Modification

摘要

Conjugated polymers doped with fullerenes show excellent photoconversion efficiencies. However, due to the poor solubility of pure C_(60) in common organic solvents, it was thought that some chemical modifications to C_(60) were required in order to load conjugated polymers with comparable weights of fullerene. Here, we report a novel way to load large amounts of unmodified C60 fullerene into the conjugated polymer poly(2-methoxy-5-(2-ethylhexoxy)-1,4-phenylenevinylene), MEH-PPV. The principle of our approach is to separate the film-deposition stage from the material-solidification stage. That is, materials are quickly solidified from dilute solution into colloidal particles, which are large enough to be collected by electrophoretic deposition. Deposition from a mixture of separate suspensions of MEH-PPV and C_(60) fullerene resulted in films consisting of isolated particles. In contrast, by using a suspension made of a dilute solution of MEH-PPV and C_(60), which was so dilute that traditional techniques such as spin-coating were not applicable, an MEH-PPV film doped with 20 mol-% C60, corresponding to an almost 1:1 ratio by weight of molecularly dispersed C_(60), was easily obtained. To the best of our knowledge, this is the first report on the successful loading of an equivalent weight ratio of unmodified C60 molecules into MEH-PPV.