Effects of Cl in Electrodeposition Baths on Morphologies of Zinc Oxide Thin Films

Thin compact layers of ZnO were grown on the conductive transparent substrate of FTO by electrochemical deposition method at 85○C for application perovskite solar cells. Different Cl concentrations and potentials are investigated to optimize the final ZnO layer. The quality of layer is evaluated by scanning electron microscopy (SEM), diffused transmittance spectroscopy (DTS) and electrochemically by ferro/ferricyanide as the model redox probes. FE-SEM images demonstrate that the FTO surface is effectively covered by ZnO for deposition times more than 400 seconds. XRD spectra indicates the preferential growth along the (001) direction for ZnO films. Evidence from cyclic voltammograms show that ZnO blocking layers deposited at t 400 s successfully suppress interfacial charge recombination. DTS data demonstrate that as Cl concentration increases, as ZnO film transmittance decreases.