Macroscopically uniform electrodeposited ZnO films on conducting glass by surface tension modification and consequent demonstration of significantly improved p–n heterojunctions

An alternative water–ethanol zinc nitrate solution is demonstrated to completely eliminate macroscopic defects that are normally prevalent in ZnO films electrochemically deposited from aqueous zinc nitrate solutions. The inclusion of 25% ethanol (by volume) reduces the surface tension of the mixture and eliminates bubble formation on the conducting glass surface during deposition. To demonstrate the importance of film uniformity, the ZnO films are employed in ZnO–Cu2O n–p heterojunctions and an order of magnitude improvement in diode behaviour is observed.

Research highlights
► Ethanol additive improves homogeneity of electrodeposited ZnO films.
► Eliminates pinholes by reducing surface tension of aqueous solution.
► Homogeneous ZnO films employed in ZnO–Cu2O heterojunctions.
► An order of magnitude improvement in diode properties observed.
► Macroscopically uniform ZnO films critical for wide variety of applications.