We investigated the internal quantum efficiencies (IQEs) of high efficiency P3HT:PCBM solar cells and found the IQEs to be wavelength dependent. Numerical modeling showed that this could be explained by the polymer and fullerene having unequal exciton harvesting efficiencies. We found that for these devices, the exciton diffusion length in PCBM is too small; excitons generated in PCBM decay before reaching the donor-acceptor interface. We also studied fullerene intercalation in the crystalline polymer pBTTT and the amorphous polymer MDMO-PPV. This work demonstrates that intercalation can be controlled by adjusting the fullerene size, clarifies the effect of intercalation on solar-cell properties and explains why intercalation may be responsible for the significant increase in the MDMO-PPV hole mobility when it is blended with PCBM.
|Original language||English (US)|
|Title of host publication||ACS National Meeting Book of Abstracts|
|State||Published - Dec 1 2010|