| 초록 |
Previous experimental studies have produced contradictory role of fullerene on the photo-oxidation of polymer:fullerene blends, with one showing that fullerene stabilizes the polymers, and another showing that it destabilizes them. In this work, we demonstrate that contradictory effect of fullerenes on the photo-oxidation of polymer:fullerene blends originates from the contrasting nanomorphologies of fullerenes. Our results show that dispersed fullerenes in mixed phase is the vital factor causing photo-oxidation of polymer donors, while aggregated fullerene phase stabilizes polymer donors. Furthermore, we demonstrate that oxidized polymers cause significant deterioration of hole transport through polymer:fullerene blends, which is comparable with a loss in efficiency of organic solar cells. We could extend our conclusions to blends systems composed of non-fullerene acceptors confirming generality of this phenomenon in organic solar cells. |
