Preparation and Characterization of Cu and Al Doped ZnO Thin Films for Solar Cell Applications

The Al- and Cu-doped ZnO nanostructured films in this study were deposited using a sputtering technique. Investigations based on X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, Hall effect measurements, and optical transmission spectroscopy was performed to analyze the structural, electrical, and optical characteristics of the prepared Al-ZnO and Cu-ZnO nanostructured films. The analyses show that doping results in enhanced conductivity as well as improved mobility in Al-ZnO and Cu-ZnO films in comparison to pure ZnO films. The Al- and Cu-doped ZnO films exhibited low resistivity (2.9 x 10(-4) omega cm for Al-ZnO and 1.7 x 10(-4) omega cm for Cu-ZnO) along with an average transmittance of around 80% in the visible spectrum. Moreover, the optical bandgaps of undoped ZnO, Al-ZnO, and Cu-ZnO nanostructures were observed as 3.3, 3.28, and 3.24 eV, respectively. Finally, solar cells were assembled by employing ZnO nanostructured thin films as photoelectrodes, resulting in efficiencies of 0.492% and 0.559% for Al-ZnO- and Cu-ZnO-based solar cells, respectively.