SEM images of (a) bare ZnO nanorods grown on a FTO substrate, and (b) full cell with CH3NH3PbI3-deposited on ZnO nanorods. Reproduced with permission from D.-Y. Son, J.-H. Im, H.-S. Kim and N.-G. Park, J. Phys. Chem. C, 2014, 118, 16567–16573. Copyright (2014) American Chemical Society.33