Figure 4From: Hydrothermal Growth and Application of ZnO Nanowire Films with ZnO and TiO2Buffer Layers in Dye-Sensitized Solar CellsTop-view and cross-sectional SEM images of ZnO nanowire arrays prepared with 7.3 mM of PEI for 40 ha–f on the bare FTO substrate andg–l on the TiO2-coated FTO substrate. The insets show high-magnification SEM imagesBack to article page