Photovoltaic Efficiency Enhancement of Cu2O Solar Cells Achieved by Controlling Homojunction Orientation and Surface Microstructure

Controlling the interface quality and surface microstructure of the cuprous oxide (Cu2O) p-n homojunction is crucial to obtaining high-efficiency film solar cells. However, the low-cost synthetic techniques for preparing such homojunction structures with a high-quality interface and designed surface microstructure still remain a challenge because of the doping difficulty for the n-type of Cu2O, especially with aqueous precursors. Herein, we report an electrochemical deposition approach to growing the Cu2O p-n homojunction by selecting proper electrolytes of different pH levels. The Cu2O film 'growth orientation and surface microstructure are controlled by adjusting the applied deposition potential and the precursor concentration. The epitaxial growth of the Cu2O homojunction with n/p films of the same crystal orientation reduce i the interface states and the formation of a textured structure on the surface helps the photons to be absorbed more effectively, which both enhance the photovoltaic conversion efficiency of Cu2O film solar cells. Our findings provide an effective method for the fabrication of Cu2O homojunctions with a high-quality interface and textured surface, which can pave the way to further improve the photovoltaic properties of Cu2O-based film solar cell devices.