Effect of Precursor Molar Ratio of [S2-]/[Zn2+] on Particle Size and Photoluminescence of ZnS:Mn2+ Nanocrystals
Effect of Precursor Molar Ratio of [S^2-]/[Zn^2＋] on Particle Size and Photoluminescence of ZnS：Mn^2＋ Nanocrystals

We investigate the influence of precursor molar ratio of S^2-]/Zn^2＋] on particle size and photoluminescence （PL） of ZnS：Mn^2＋ nanocrystMs. By changing the S^2-]/Zn^2＋] ratio from 0.6 （Zn-rich） to 2.0 （S-rich）, the particle size increases from nearly 2. 7nm to about 4.Ohm. The increase in the ratio of S^2-]/Zn^2＋] cadses a decrease of PL emission intensity of ZnS host while a distinct increase of Mn^2＋ emission. The maximum intensity for the luminescence of Mn^2＋ emission is observed at the ratio of S^2-]/Zn^2＋] ≈ 1.5. The possible mechanism for the results is discussed by filling of S^2- vacancies and the increase of Mn^2＋ ions incorporated into ZnS lattices.