Excited-state regulation in eco-friendly ZnSeTe-based quantum dots by cooling engineering

The production of high-quality eco-friendly quantum dots (QDs) is challenging because of the efficient yet elusive nonradiative recombination within. This study examined the effects of cooling engineering on regulating the excited states to realize high-quality ZnSeTe core-shell QDs. The presence of ultrafast hot-carrier trapping and band-edge carrier trapping is responsible for the poor emission efficiency in ZnSeTe QDs. The above processes can be suppressed simultaneously by engineering the cooling process, and the underlying mechanisms are interrogated by combined electronic and spectroscopic characterization. The engineered ZnSeTe QDs exhibited record-high efficiency (>90%) and stability that were comparable to those of the canonical CdSe QDs. Leveraging on the achievement, the ZnSeTe QD-based white light-emitting diodes (WLEDs) showed excellent optical performance, including a high color-rendering index of 80 and an appropriate correlated color temperature of 7391 K. Furthermore, the WLEDs could serve as light sources in eco-friendly visible light communication. These results highlight the feasibility of eco-friendly QDs for practical applications without environmental hazards.