Cu₂O growth characteristics on an array of ZnO nanorods for the nano-structured solar cells

The preferred crystal orientation of the electrochemically deposited (ECD) Cu₂O film on substrates with an array of ZnO nanorods (NRs) has been extensively investigated. For Cu₂O film ECD on an array of ZnO NRs, texture of the ECD Cu₂O films can be manipulated either by the pH value of the solution, the plating current, or the ZnO nanorod (NR) density. With a fixed plating current and at high pH values, highly (111)-preferred Cu₂O film can only be obtained with certain NR densities, whereas NR too dense or too sparse can only grow a (200)-preferred Cu₂O film. Low pH value or low plating current density is not able to form (111)-preferred film regardless of NR density. The texture change of the ECD Cu₂O film deposited on ZnO NRs and its enhanced growth rate along the <100> direction are attributed to the specific electric field configurations for substrate with NRs and the parallel receiving angle of the reactants. The degree of ZnO NR's influence on the preferred Cu₂O growth and its growth characteristics are investigated and revealed.