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Influence of Glass Composition on the Luminescence Mechanisms of CdSe Quantum Dot-Doped Glasses

preprint
submitted on 31.03.2021, 08:00 and posted on 31.03.2021, 13:14 by Wenke Li, Xiujian Zhao, Chao Liu, François-Xavier Coudert

In this work, we characterized the electronic structure of CdSe quantum dots embedded in a series of x Na2O, (1–x) SiO2 glass matrices (x = 0, 0.25, 0.33 and 0.5). We analyzed the impact of the glass matrix composition on both the atomic structure of the quantum dot (QD) and the QD/glass interface, as well as the luminescence mechanisms, using density functional theory (DFT) calculations. The increase of Na2O content in the glass matrices was found to promote the formation of Cd–O and Se–Na interfacial bonds, and disrupting the Cd–Se bonds network. In particular, we show that the glass composition directly affects the nature of the highest occupied molecular orbitals (HOMO). According to the atomic structure, the band gap distribution and the density of states calculation, we find that there is significant reconstruction of the QD, and that the picture sometimes proposed of a “pristine QD” surrounded by glass is not realistic. The introduction of CdSe QD significantly decreased the bandgap of the glass compared to pristine glasses, and the interfacial bonds greatly contributed to the frontier orbitals without forming midgap states. We propose a new energy diagram, quite different from the traditional model, to explain the luminescence of CdSe quantum dot- doped glasses, originating from the intrinsic emission of this hybrid system {QD + glass}. These results improve our understanding of the luminescence of CdSe quantum dot-doped glasses, explaining the reason for the poor quantum efficiency and broad emission linewidth compared with their colloidal counterparts.

History

Email Address of Submitting Author

fx.coudert@chimieparistech.psl.eu

Institution

CNRS / PSL University

Country

France

ORCID For Submitting Author

0000-0001-5318-3910

Declaration of Conflict of Interest

No conflict of interest

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