Enhancing Dielectric Screening for Auger Suppression in CdSe/CdS Quantum Dots by Epitaxial Growth of ZnS Shell

Auger recombination is the main nonradiative process in multicarrier states of high-quality quantum dots (QDs). For the most-studied CdSe/CdS core/shell QDs, we effectively reduce the biexciton Auger rate by enhancing dielectric screening of band-edge carriers via epitaxial growth of additional ZnS shells. Super volume scaling of negative-trion Auger lifetime for CdSe/CdS core/shell QDs is achieved with the outermost ZnS shells. The volume of CdSe/CdS/ZnS QDs can be less than half that of CdSe/CdS QDs with the same negative-trion Auger lifetime. Auger suppression by the ZnS shells is more pronounced for QDs with wave functions of band-edge carriers spreading close to the inorganic-organic interface, such as CdSe/CdS QDs with small cores. A maximum drop of biexciton Auger rate of similar to 50% and a maximum enhancement of biexciton emission quantum yield of 75% are achieved. Auger engineering by dielectric screening opens up new opportunities to improve the emission properties of multicarrier states in QDs.

Automated summary

Auger recombination is effectively reduced in high-quality quantum dots by enhancing dielectric screening of band-edge carriers with additional ZnS shells. The volume scaling of negative-trion Auger lifetime is achieved with ZnS shells, which can be less than half the volume of QDs without these shells, while also enhancing the biexciton emission quantum yield. The engineering of Auger effects through dielectric screening presents new opportunities for improving emission properties in multicarrier states of quantum dots.