Fig. 3.

The top-down SEM images of template, P3HT film, and PCBM film surface. a The top-down SEM image of patterned silk fibroin template surface, scale bar = 500 nm; b the top-down SEM image of P3HT nanograting film surface fabricated by silk fibroin template (a), scale bar = 500 nm; c the top-down SEM image of PCBM surface deposited on the top of P3HT nanograting film, scale bar = 150 nm