Synthesis of Cu2+ doped ZnO@ZnCdS thin film: Optical and electrochemical characterization

Abstract

Doping strategies modify the optical and electrochemical characteristics of materials. In this research, we investigated the impact of Cu2⁺ doping in ZnO@ZnCdS nanocomposites synthesized via the co-precipitation approach. A comprehensive analysis was conducted on the structural, morphological, optical, and electrochemical features of the samples using various techniques, including scanning electron microscopy (SEM), atomic force microscopy (AFM), Energy Dispersive X-ray analysis (EDX), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), UV–Visible absorption, and photoluminescence (PL). Notably, Cu2⁺ doping induces changes in morphology, crystal size, absorption spectra, and band gap energy. Surface investigations reveal a flower-like structure, while XRD analysis indicates an increase in crystal size from 25.5 to 35.2 in thin films with copper content. The absorption spectra of UV–visible-doped ZnO@ZnCdS thin films exhibit reduced peak intensity upon Cu2⁺ addition. Also, optical absorption analysis shows a shift towards longer wavelengths in the emission of ZnO@ZnCdS due to Cu2⁺ inclusion during doping. Likewise, the band gap energy ranges from 1.37 eV to 2.22 eV for ZnO@ZnCdS and Cu2⁺ doped ZnO@ZnCdS, respectively, as determined using Tauc plots. PL spectrum of the Cu2⁺ doped ZnO@CdS nanocomposite indicates emissions in the blue and green regions. Specifically, under 325 nm excitation, the copper-doped material displays a prominent blue and a less intense red emission at 420 nm at 685 nm, respectively. Furthermore, the electrochemical analysis revealed that doping caused a reduction in Rct and an elevation in CSP. These results offer important considerations for the development of cutting-edge functional optoelectronic materials.