Herein, we designed and fabricated photovoltaic (PV) devices with optimal efficiency of Cu2O buffer layers (p-Cu2O/n-Cu2O/ZnO and p-Cu2O/p−-Cu2O/ZnO) through electrochemical deposition (ECD) processing. PV devices with two types of buffer layers, n-Cu2O and p−-Cu2O, were produced by ECD and consisted of a layer of nanorod ZnO on ITO, an n-Cu2O or a p−-Cu2O buffer layer, a p-Cu2O layer, and a sputtered Ag layer. Results revealed that the interface between the ZnO film and the Cu2O buffer, and thickness of the buffer layer were crucial factors to affect PV device performance. The nanorod structure of ZnO transformed into a flake structure during the ECD of n-Cu2O on ZnO. However, ZnO retained the same morphology during the ECD of p−-Cu2O on ZnO. The optimal thicknesses of the Cu2O buffer in the PV device were obtained to enhance the PV efficiency from 0.046 (p-Cu2O/ZnO) to 0.17% (p-Cu2O/p−-Cu2O/ZnO). The p-Cu2O/ZnO PV performance was improved through the fabrication and incorporation of Cu2O buffers. [ABSTRACT FROM AUTHOR]