Oxide p-n Heterojunction of Cu2 O/ZnO Nanowires and Their Photovoltaic Performance

Oxide p-n heterojunction devices consisting of p-Cu sub(2) O/n-ZnO nanowires were fabricated on ITO/glass substrates and their photovoltaic performances were investigated. The vertically arrayed ZnO nanowires were grown by metal organic chemical vapor deposition, which was followed by the electrodeposition of the p-type Cu sub(2) O layer. Prior to the fabrication of solar cells, the effect of bath pH on properties of the absorber layers was studied to determine the optimal condition of the Cu sub(2) O electrodeposition process. With the constant pH 11 solution, the Cu sub(2) O layer preferred the (111) orientation, which gave low electrical resistivity and high optical absorption. The Cu sub(2) O (pH 11)/ZnO nanowire-based solar cell exhibited a higher conversion efficiency of 0.27% than the planar structure solar cell (0.13%), because of the effective charge collection in the long wavelength region and because of the enhanced junction area.