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

Abstract

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 × 10−4 Ω cm for Al–ZnO and 1.7 × 10−4 Ω 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.