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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 ∼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.

We introduce stoichiometry control within both core and shell regions of InP/ZnSe/ZnS core/shell/shell quantum dots (QDs) to advance their properties drastically, approaching those of state-of-the-art CdSe-based QDs. The resulting QDs possess near-unity photoluminescence quantum yield, monoexponential decay dynamics, narrow line width, and nonblinking at a single-dot level. Quantum-dot light-emitting diodes (QLEDs) with the InP/ZnSe/ZnS core/shell/shell QDs as emitters exhibit a peak external quantum efficiency of 12.2% and a maximum brightness of >10 000 cd m–2, greatly exceeding those of the Cd/Pb-free QLEDs reported in literature. These results pave the way toward Cd/Pb-free QDs as outstanding optical and optoelectronic materials.

Indium-based quantum dots (QDs), such as InP, InAs, and CuInS2, are considered as the most promising candidates as cadmium/lead-free QDs. At present, the synthesis of these QDs is limited by the unbalanced reactivity of various precursors, specifically the sluggish reactivity of indium alkanoates. Here, we demonstrate that, with a phosphine-to-indium molar ratio beyond 3:1, decarboxylation reactions of indium alkanoates by aliphatic tertiary organophosphines become apparent, forming a series of new indium complexes, instead of purely enhancing the solubility of indium alkanoates at a low molar ratio. These new indium complexes are proven to be highly reactive indium precursors. By varying the organophosphine and indium alkanoate molar ratios, the resulting indium-complexes offer the needed tunability of reactivity for the synthesis of high-quality In-based QDs.