Tailoring the structural, optical, hydrophobicity and electrical properties of ZnO thin films by copper doping for self-clean optoelectronic application

Abstract

Optoelectronic devices such as solar panels, cameras, screens, and sensors frequently suffer reduced performance due to dust accumulation. Incorporating self-cleaning features not only sustains their efficiency but also minimizes maintenance expenses, especially for large or challenging-to-access setups. In this study, copper doped-zinc oxide (CZO) thin films with varying copper (Cu) concentrations were created using the reactive co-sputtering process. These films underwent a comprehensive analysis, including X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy to examine their structure, morphology, and elemental composition. Optical properties were investigated through UV–Vis spectroscopy, while hydrophobicity and electrical characteristics were assessed with contact angle and I–V measurements. Spectroscopic ellipsometry was employed to analyse surface attributes. The results confirmed that as Cu concentrations increased, the crystallite and grain size of ZnO in the films also increased. A red shift in the band gap was observed in UV–Vis spectroscopy, and Cu doping effectively reduced the electrical resistivity of the ZnO thin film. The CZO thin film, with a 60 nm thickness, low roughness (1.49 nm), high optical transmittance (around 80.20 %), a wide band gap (3.22 eV), a substantial contact angle (113°), and low electrical resistivity (5.9 × 105 Ω cm), holds great promise for use in transparent, conductive, and self-cleaning optoelectronic devices.

Keywords

• Cu doped ZnO
• Reactive-co-sputtering
• Hydrophobic
• Ellipsometry
• Electric-resistivity