Nanoimprinted solar cells with large molecular weight P3HT nanogratings with enhanced molecular alignment

We demonstrate efficient polymer solar cells made from large molecular weight (MW) poly(3-hexylthiophene-2,5-diyl) (P3HT) nanostructures made by nanoimprint lithography (NIL). We found NIL allows the polymer with higher MW (> 40 kDa) to organize more strongly than lower MW, which is desired for efficient charge transport but difficult to achieve previously. Solar cells with large MW P3HT nanogratings show a high power conversion efficiency of 4.4%, which is among the best reported for the same materials.