Depending upon the different defect related transitions, ZnO NP can look green, yellow and orange.
The nonstoichiometric ZnO undergoes the following reaction:
ZnO----Zn^2+1/2O2+2e
The excess Zn^2 thus formed get trapped into the vacant interstitial sites and the electrons in the neighbouring interstitial sites; of course maintaing theelectrical neutrality. These loosely elecrtons absorb in blue region to emit orange color.
REFERENCE:
Green, yellow, and orange defect emission from ZnO nanostructures: Influence of excitation wavelength
A. B. Djurišić1,a), Y. H. Leung1, K. H. Tam1, L. Ding2, W. K. Ge2, H. Y. Chen3 and S. Gwo3
Depending upon the different defect related transitions, ZnO NP can look green, yellow and orange.
The nonstoichiometric ZnO undergoes the following reaction:
ZnO----Zn^2+1/2O2+2e
The excess Zn^2 thus formed get trapped into the vacant interstitial sites and the electrons in the neighbouring interstitial sites; of course maintaing theelectrical neutrality. These loosely elecrtons absorb in blue region to emit orange color.
REFERENCE:
Green, yellow, and orange defect emission from ZnO nanostructures: Influence of excitation wavelength
A. B. Djurišić1,a), Y. H. Leung1, K. H. Tam1, L. Ding2, W. K. Ge2, H. Y. Chen3 and S. Gwo3