Synthesis and optical properties of core/shell ternary/ternary CdZnSe/ZnSeS quantum dots

• CdZnSe QDs, emission range 530–607 nm, were synthesized by the temperature variation.
• Shelling ZnSeS on CdZnSe QDs increases average emission quantum yield by 2–17 times.
• CdZnSe/ZnSeS QDs are good single-photon emitters with less blinking than CdZnSe QDs.

In this paper we report on the synthesis of ternary/ternary alloyed CdZnSe/ZnSeS core/shell quantum dots (QDs) by embryonic nuclei-induced alloying process. We synthesized CdZnSe core QDs emitting in the spectral range of 530–607 nm with various Cd/Zn ratios, depending on the core synthesis temperature. By shelling ZnSeS on the CdZnSe core QDs, the average luminescence quantum yield is increased by a typical factor of 2 up to 17, which we attribute to the reduction of number of non-emitting QDs. The single-photon emitter micro-photoluminescence study showed that the CdZnSe/ZnSeS core/shell QDs are good single-photon emitters and their blinking properties were improved compared to the CdZnSe core QDs. Quantum yields up to 25% were measured for the core/shell samples, demonstrating the potential for high-quality ternary/ternary QDs fabrication.