Issue 3, 2024

Enhancement mechanism of quantum yield in core/shell/shell quantum dots of ZnS–AgIn5S8/ZnIn2S4/ZnS

Abstract

To achieve a high quantum yield (QY) of nanomaterials suitable for optical applications, we improved the optical properties of AgIn5S8 (AIS) quantum dots (QDs) by employing an alloyed-core/inner-shell/outer-shell (ZAIS/ZIS/ZnS) structure. We also investigated the mechanism of optical transitions to clarify the improvement of QYs. In AIS, the low-energy absorption near the band edge region is attributed to the weakly allowed band gap transition, which gains oscillator strength through state intermixing and electron–phonon coupling. The main photoluminescence is also ascribed to the weakly allowed band gap transition with characteristics of self-trapped excitonic emission. With alloying/shelling processes, the weakly allowed transition is enhanced by the evolution of the electronic structures in the alloyed core, which improves the band gap emission. In shelled structures, the nonradiative process is reduced by the reconstructed lattice and passivated surface, ultimately leading to a high QY of 85% in ZAIS/ZIS/ZnS. These findings provide new insights into the optical transitions of AIS because they challenge previous conclusions. In addition, our work elucidates the mechanism behind the enhancement of QY accomplished through alloying/shelling processes, providing strategies to optimize nontoxic QDs for various applications using a green chemistry approach.

Graphical abstract: Enhancement mechanism of quantum yield in core/shell/shell quantum dots of ZnS–AgIn5S8/ZnIn2S4/ZnS

Supplementary files

Article information

Article type
Paper
Submitted
27 Nov 2023
Accepted
27 Dec 2023
First published
28 Dec 2023
This article is Open Access
Creative Commons BY license

Nanoscale Adv., 2024,6, 925-933

Enhancement mechanism of quantum yield in core/shell/shell quantum dots of ZnS–AgIn5S8/ZnIn2S4/ZnS

S. Jeong, M. Ko, S. Nam, J. H. Oh, S. M. Park, Y. R. Do and J. K. Song, Nanoscale Adv., 2024, 6, 925 DOI: 10.1039/D3NA01052J

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