Defect-mediated structural, optical, and antibacterial properties of Y/B codoped ZnO nanoparticles

Veziroglu S., Arda L., TAV C., Yalcin B., YAHŞİ U., ÖZDOĞAN K.

European Physical Journal Plus, cilt.141, sa.10, 2026 (SCI-Expanded, Scopus)

Özet

Y/B-codoped ZnO nanoparticles (NPs), with a nominal composition of Zn0.95−xB0.05YxO (x = 0.00–0.05), were synthesized using the sol–gel method to study the effects of defects on their optical and antibacterial properties. Structural characterization through X-ray diffraction confirmed that all samples crystallize in the hexagonal wurtzite structure, with lattice distortions assessed via variations in the c/a ratio. The type and density of defects, along with crystal quality, were systematically analyzed using photoluminescence (PL) spectroscopy and positron annihilation lifetime spectroscopy (PALS). Optical absorption measurements were conducted using a Shimadzu UV-2600 spectrophotometer. The optical band gaps were determined, and refractive indices were calculated utilizing five different theoretical models. The results show a nonmonotonic variation in the optical band gap with Y content, peaking at 3.262 eV when x = 0.02. In contrast, the refractive index exhibits little dependence on Y concentration, despite oscillatory lattice strain, which is tensile at maximum strain and compressive at minima. An increase in Urbach energy with dopant concentration indicates greater structural disorder and the presence of defect-induced band-tail states. PL analysis reveals both acceptor-type (A⁰(VZn)) and donor-type (VO, D⁰(Znᵢ)) defects, with their increasing concentrations contributing to band gap narrowing and enhanced band-edge tailing. Y/B codoping allows for the controlled modification of lattice parameters, defect populations, and optical responses while maintaining the structural integrity of wurtzite ZnO. Additionally, the Y/B-codoped ZnO NPs demonstrate significant antibacterial activity against Staphylococcus aureus, whereas no notable activity is observed against Escherichia coli. This antibacterial effect is primarily attributed to the generation of reactive oxygen species (ROS) mediated by oxygen vacancies, rather than by particle-size effects.