Exploring the impact of Zr concentration on the optical, morphological and structural properties of Zr–doped CuSe nanocrystal films

Nanocrystalline undoped CuSe and Zr-doped CuSe thin films were successfully synthesized by the electrodeposition technique using different Zr doping concentrations. The structural, optical, morphological, and vibrational properties of the deposited films were investigated using X-ray diffraction (XRD), UV–Vis–NIR spectroscopy, scanning electron microscopy (SEM), and Raman spectroscopy, respectively. The optical studies revealed that the undoped CuSe film exhibited relatively low absorbance in the UV–visible region, with absorbance increasing toward the near-infrared (NIR) region. The incorporation of Zr enhanced the absorbance throughout the UV–visible region, and the absorbance increased progressively with increasing Zr concentration. The optical band gap of the undoped CuSe film was determined to be 1.00 eV, while the Zr-doped films exhibited wider band gaps ranging from 1.20 to 1.80 eV, indicating a significant influence of Zr incorporation on the electronic structure of the material. SEM analysis showed that the undoped CuSe film consisted of uniformly distributed rod-like nanograins on the substrate surface. Upon Zr doping, the morphology evolved into larger and more densely packed chain-like structures, with improved continuity and surface coverage as the dopant concentration increased. XRD results confirmed the crystalline nature of the films and revealed an increase in diffraction peak intensity with increasing Zr concentration, indicating improved crystallinity. A shift of the diffraction peaks toward higher diffraction angles was observed, suggesting successful incorporation of Zr ions into the CuSe lattice. Correspondingly, the lattice constant decreased from 5.840 Å for the undoped CuSe film to values in the range of 5.291–3.972 Å for the Zr-doped films. Raman spectra exhibited a characteristic CuSe vibrational mode near 264 cm⁻¹ , confirming the preservation of the CuSe crystal structure after Zr incorporation. These results demonstrate that Zr doping significantly modifies the optical, structural, and morphological properties of CuSe thin films, making them promising candidates for optoelectronic and energy-related applications.