Key factors in the stability of doped ZnSe:Mn@MPA semiconductor nanocrystals

3-mercaptopropionic acid (MPA) capped ZnSe:Mn semiconductor nanocrystals (ZnSe:Mn@MPA NCs) were prepared in aqueous solution. It was found that the NCs appear as macroscopic precipitates after stored for 10 d. The change law of the NCs in three distinguished stages was studied. The results displayed that the optical stability of as-prepared NCs capped with MPA stabilizer is correlated with the depletion of MPA, which leads to the decomposition of ZnSe:Mn NCs under the existence of photo-induced holes. ZnS protective layer was formed on the surface of ZnSe:Mn@MPA NCs by epitaxial growth method to inhibit the photodegradation of MPA.