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Co/B co‐doped ZnO nanoparticles, denoted as Zn0.95‐xBxCo0.05O, are synthesized using the sol–gel method to explore the effects of the defects on optical properties. The stoichiometry is adjusted by varying the doping levels (x = 0.00, 0.01, 0.02, 0.03, 0.04, and 0.05). X‐ray diffraction is employed to analyze the structural characteristics of all Co/B co‐doped ZnO nanoparticles, confirming the presence of a hexagonal Wurtzite structure by assessing the c/a ratios. To investigate structural defects, photoluminescence properties are measured using the Fluorescence Spectrophotometer, revealing violet, blue, green, and red emissions. With the doped of boron (B), a shift from green emission to blue emission occurs, indicating a transformation of singly charged oxygen vacancies (VO+) to VZn vacancies. Fourier Transform Infrared (FTIR) spectra (4000–400 cm−1) are acquired using the Perkin Elmer Spectrum Two FTIR‐ATR spectrophotometer. The surface morphology, crystallite size, and nanoparticle shapes are characterized through Transmission Electron Microscope (TEM) analysis. Elemental compositions are determined using Electron Dispersive Spectroscopy (EDAX). The Shimadzu 2600 UV‐Spectrophotometer is used to examine optical characteristics. The samples' energy band gaps are calculated, and the impact of dopant elements on these optical characteristics is examined. Five different models are used to compute the refractive index. [ABSTRACT FROM AUTHOR]

Co/B co-doped ZnO (Zn 0.93-x Co x B 0.07 O, x = 0.00, 0.01, 0.02, 0.03, 0.04, and 0.05) nanoparticles were synthesized by the hydrothermal method to investigate the effect of cobalt and boron on the structural, microstructural, and optoelectronic properties of ZnO nanoparticles. The X-ray diffraction method was used for the structural analysis and single phases were found for all Co/B co-doped ZnO nanoparticles. Scanning Electron Microscope (SEM) technique was used to determine the surface morphology, particle size, and the shapes of the nanoparticles. The elemental compositions of the nanoparticles were obtained by electron dispersive spectroscopy (EDS). Hexagonal Wurtzite structure was proved by c/a ratios of the ZnCoBO nanoparticles. The Fourier transform infrared (FTIR) studies were performed and explained. The energy band gaps of the samples were calculated and the effects of dopant elements on optical properties were discussed. The maximum band gap occurred for Zn 0.93 B 0.07 O with a band gap energy of E g = 3.26 eV. The refractive index was calculated using the energy band gap with five different models. The grain sizes and the band gap energies fluctuated as the doping ratio increased. The results showed that the refractive index strongly depends on the Co concentration nonlinearly. It was found that doping cobalt increased the Urbach energy value of B-doped ZnO nanoparticles. The increase in E u indicates that the structural disorder and the number of defects in the Zn 0.93-x Co x B 0.07 O structures increased with increasing concentration of Co in the Zn 0.93-x Co x B 0.07 O structures. The highest value of Urbach energy was approximately found in the range of 1259 and 1469 meV for 3% Co. Moreover, for 3% Co the concentration-dependent microstrain (Ɛ) values also reached the maximum, dislocation density δ had also the maximum value. [ABSTRACT FROM AUTHOR]