Phase separation of co-evaporated ZnPc:C

We demonstrate phase separation of co-evaporated zinc phthalocyanine (ZnPc) and fullerene (C 60) for efficient organic photovoltaic cells. With introducing a poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) film and a crystalline copper iodide film on indium tin oxide, 20-nm-thick ZnPc film adopts a lying-down crystalline geometry with grain sizes of about 50 nm. This surface distributed with strong interaction areas and weak interaction areas enables the selective growth of ZnPc and C 60 molecules during following co-evaporation, which not only results in a phase separation but also improve the crystalline growth of C 60. This blend film greatly enhances the efficiencies in photocurrent generation and carrier transport, resulting in a high power conversion efficiency of 4.56 under 1 sun.