Tailoring the Structural and Optical Properties of Ce-Doped ZnO Nanostructures for Potential Electron Transport Layer Application in Perovskite Solar Cells

This study investigates the structural, morphological, and optical modifications induced by cerium (Ce) doping in zinc oxide (ZnO) nanostructures synthesized by a controlled hydrothermal method. X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM/TEM), Fourier-transform infrared spectroscopy (FTIR), Ultraviolet-Visible spectroscopy (UV–vis), and photoluminescence (PL) spectroscopy were used for characterization. XRD confirmed that all samples retained the hexagonal wurtzite structure after Ce incorporation. The crystallite size varied between 32.6 and 49.5 nm, showing a non-monotonic dependence on cerium (Ce) concentration. SEM and TEM revealed a gradual morphological transformation from interlinked hexagonal particles to spherical structures with increasing Ce content. Optical analysis showed slight bandgap variation from 3.209 to 3.226 eV, indicating modification of the ZnO electronic structure. Photoluminescence spectra exhibited enhanced visible emission in the 650–700 nm region with increasing Ce concentration, attributed to defect-mediated radiative recombination associated with Ce³⁺/Ce⁴⁺ states. These findings demonstrate that controlled Ce doping effectively tailors the structural and optical properties of Zinc oxide (ZnO), 16 through defect engineering. The resulting Ce-doped ZnO nanostructures show potential for applications requiring tunable charge transport and light-management properties in optoelectronic materials.