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<p>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.
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Influence of Glass Composition on the Luminescence Mechanisms of CdSe Quantum Dot-Doped Glasses
