Defects suppression and Co–O–Co bonding mediated influences to enhance the luminescence characteristics of Co doped ZnO nanoparticles

Highlights: • Co–O–Co bonding influences are observed on Co doped ZnO nanoparticles. • Suppression of Zinc interstitials, Zn_i and oxygen vacancies, V_o is noted with increased doping. • Exceptionally low level of BMP density (3.22 × 10⁷/cm³) is noted in 5 mol% doped nanoparticles. • Enhanced luminescence characteristics justify the nanoparticles suitability for optical devices. Co–O–Co bonding mediated influences are discussed on the structural, defect content, magnetization and luminescence characteristics of Co doped ZnO nanoparticles. X-ray diffraction (XRD) studies indicated an increased fraction of secondary phase while varying Co doping levels from 0.45 to 5 mol%. Contrarily, a reverse trend is noted on the concentration of Zinc interstitials, Zn_i and Oxygen vacancies, V_o defects through Photoluminescence (PL) spectroscopy. For 5 mol% doping level, Bound Magnetic Polaron (BMP) model fitting of Magnetization versus magnetic field, M(H, 300 K) curve yields an exceptionally low level of BMP density i.e., 3.22 × 10⁷/cm³ thereby governing the dominance of Co–O–Co exchange interactions over V_o based Co–V_o–Co interactions; while PL result displays an enhanced UV emission efficiency suitable for short wavelength optical devices.