Structural and optical properties of Cu-doped ZnO nanoparticles synthesized by co-precipitation method for solar energy harvesting application

Cu-doped ZnO nanoparticles were synthesized by co-precipitation method using zinc nitrate (Zn(NO₃)₂-6H₂O), copper(II) nitrate trihydrate (Cu(NO₃)₂-3 H₂O) as starting precursors for Zn and Cu sources, respectively. The structural properties of powders were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and X-ray Photoelectron Spectroscopy (XPS). The XRD results disclose that Cu-doped ZnO nanopowders are in hexagonal wurtzite structure and their crystallinities are deteriorated with increasing Cu doping content. Meanwhile, XPS results indicate the existence of Cu ion with relevant electronic state in ZnO. Optical properties of the samples were investigated by mean of their absorption and the results suggest that Cu additive has significant effects on their crucial optical properties that can be tuned to meet the requirement for practical solar energy harvesting applications such as sun-light photocatalyst and photovoltaic devices.