Related Experiment Video
Updated: Feb 24, 2026

Low-energy Cathodoluminescence for OxyNitride Phosphors
Published on: November 15, 2016
Strong Deep-Level-Emission Photoluminescence in NiO Nanoparticles
Ashish Chhaganlal Gandhi1,2, Sheng Yun Wu3
1Department of Physics, National Dong Hwa University, Hualien 97401, Taiwan. acg.gandhi@gmail.com.
Abstract:
Nickel oxide is one of the highly promising semiconducting materials, but its large band gap (3.7 to 4 eV) limits its use in practical applications. Here we report the effect of nickel/oxygen vacancies and interstitial defects on the near-band-edge (NBE) and deep-level-emission (DLE) in various sizes of nickel oxide (NiO) nanoparticles. The ultraviolet (UV) emission originated from excitonic recombination corresponding near-band-edge (NBE) transition of NiO, while deep-level-emission (DLE) in the visible region due to various structural defects such as oxygen vacancies and interstitial defects. We found that the NiO nanoparticles exhibit a strong green band emission around ~2.37 eV in all samples, covering 80% integrated intensity of PL spectra. This apparently anomalous phenomenon is attributed to photogenerated holes trapped in the deep level oxygen vacancy recombining with the electrons trapped in a shallow level located just below the conducting band.
Related Concept Videos
Photoluminescence: Applications
Photoluminescence: Fluorescence and Phosphorescence
A pair of electrons in a...
Variables Affecting Phosphorescence and Fluorescence

