Solid solution phenomenon in the amorphous conjugated polymer:fullerene bulk heterojunction structure

The PCDTBT:PC71BM blend with less than 20% PC71BM may form a kind of solid solution structure, which demonstrates a deeper HOMO level, a higher hole mobility, more free charges and less trap density than those of the pure PCDTBT film. A graphical schematic illustrates the interpenetrating networks composed of the solid solution and PC71BM in a practical PCDTBT:PC71BM BHJ solar cells.106