"Flash" synthesis of "giant" Mn-doped CdS/ZnSe/ZnS nanocrystals with ZnSe layer as hole quantum-well

Usually, exciton-Mn energy transfer in Mn-doped CdS/ZnS nanocrystals (NCs) can readily outcompete the exciton trapping by an order of magnitude. However, with the accumulation of non-radiative defects in the giant shell during the rapid growth of the thick shell (up to \textasciitilde 20 monolayers in no more than 10 minutes), the photoluminescence (PL) quantum yield of this kind of “giant” NCs is significantly reduced by the accumulation of non-radiative defects during the rapid growth of thick shell. That is because the exciton-Mn energy transfer in Mn-doped CdS/ZnS NCs is significantly inhibited by the hole trapping as the major competing process, resulting from the insufficient hole-confinement in CdS/ZnS NCs. Accordingly “flash” synthesis of giant Mn-doped CdS/ZnSe/ZnS NCs with ZnSe layer as hole quantum-well is developed to suppress the inhibition. Meanwhile Mn$^{\mathrm{2+}}$ PL peak changes profoundly from \textasciitilde 620 nm to \textasciitilde 540 nm after addition of ZnSe layer. Studies are under the way to explore the relevant mechanisms.