Figure 2From: Controllable synthesis of flake-like Al-doped ZnO nanostructures and its application in inverted organic solar cells The SEM images of ZnO nanostructures grown in a solution with different Al concentrations. (a) 0 mM; (b) 1 mM; (c) 2 mM; (d) 4 mM. Scale bar, 300 nm.Back to article page