What does this research mean for the field?

B-doping in ZnO nanoparticles introduces significant defect states that modify the optical properties and enhance their potential for applications in UV photodetectors and organic photovoltaic devices. Novelty: ClaimNovelty.NOVEL_FINDING. Consensus alignment: ConsensusAlignment.NEUTRAL.

What question did this study set out to answer?

This research investigates how boron doping influences defect chemistry and optical properties of ZnO nanoparticles.

February 19, 2026Open Access

B-Doped ZnO Nanoparticles: Defect Chemistry, Tensile Strain, and Tunable Optical Response

Key Points

This research investigates how boron doping influences defect chemistry and optical properties of ZnO nanoparticles.
Synthesis of ZnO and ZnO:5%B nanoparticles via sol–gel method.
X-ray diffraction used to determine crystallite sizes and microstrain.
Photoluminescence spectra analyzed to identify emission characteristics.
Electron spin resonance measurements conducted to assess spin density.
Crystallite sizes ranged from 32.37–39.63 nm with microstrain values (1.98–8.03)×10−4.
Boron doping introduced significant band-tail states, decreasing optical band gap to 3.216 eV.
Strong violet and blue emissions observed from zinc interstitials and vacancies.
High spin density indicated by strong defect-related signal at g≈2.294.

Abstract

ZnO and ZnO:5%B nanoparticles produced by sol–gel synthesis exhibit a single-phase wurtzite structure. X-ray diffraction (XRD) investigation reveals crystallite sizes in the range of 32.37–39.63 nm and microstrain values on the order of (1.98–8.03)×10−4, despite the Uniform Stress Deformation Model (USDM) indicating the presence of considerable tensile stress. Significant band-tail states are introduced via boron doping, resulting in Urbach energies ranging from 110 to 193 meV and a narrowed optical band gap of 3.216 eV. With a refractive index range of 2.05–2.71, the material exhibits tunable optical characteristics. Violet and blue emissions originating predominantly from zinc interstitials (Znᵢ) and zinc vacancies (VZn) dominate the photoluminescence spectra, while oxygen interstitial-related contributions remain relatively weak. A high spin density is confirmed by electron spin resonance measurements, which reveal a strong defect-related signal at g≈2.294. The formation of Znᵢ/VZn defect centers due to charge compensation and ionic size mismatch induced by B3+ substitution for Zn2+ significantly modifies the band-edge states and optical constants. These defect-engineered properties render the material promising for applications in ultraviolet (UV) photodetectors, transparent conducting oxides, and electron transport layers in organic photovoltaic devices.

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