Luminescent properties of cadmium selenide quantum dots in fluorophosphate glasses

Liu

et al. 2021

J. Phys. Chem. C

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 HOMO-LUMO gap 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.

Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Liu

et al. 2021

J. Phys. Chem. C

“…Thus, QDs such as CdSe, − PbS, and perovskite QDs − have been embedded in glasses and have attracted a lot of attention. However, the highest reported PLQYs for CdSe and CsPbBr 3 QDs embedded in glass matrices are 48.6% and 86.9%, respectively, which are much lower than their colloidal counterparts. The poor emissive properties of QDs embedded in glasses greatly hinder their commercial applications and the underlying mechanism has not been fully explored yet.…”

Section: Introductionmentioning

confidence: 89%

Defective Nature of CdSe Quantum Dots Embedded in Inorganic Matrices

et al. 2022

J. Am. Chem. Soc.

Quantum dots (QDs) embedded in inorganic matrices have been extensively studied for their potential applications in lighting, displays, and solar cells. While a significant amount of research studies focused on their experimental fabrication, the origin of their relatively low photoluminescence quantum yield has not been investigated yet, although it severely hinders practical applications. In this study, we use time-dependent density functional theory (TDDFT) to pinpoint the nature of excited states of CdSe QDs embedded in various inorganic matrices. The formation of undercoordinated Se atoms and nonbridging oxygen atoms at the QD/glass interface is responsible for the localization of a hole wave function, leading to the formation of lowenergy excited states with weak oscillator strength. These states provide pathways for nonradiative processes and compete with radiative emission. The photoluminescence performance is predicted for CdSe QDs in different matrices and validated by experiments. The results of this study have significant implications for understanding the underlying photophysics of CdSe QDs embedded in inorganic matrices that would facilitate the fabrication of highly luminescent glasses.

“…Thus, QDs such as CdSe, [11][12][13][14] PbS, 15 and perovskite QDs, [16][17][18][19][20] have been embedded in glasses and attracted a lot of attention. However, the highest reported PLQYs for CdSe and CsPbBr3 QDs embedded in glass matrices are 48.6% 21 and 86.9% 18 , respectively, much lower than their colloidal counterparts. The poor emissive properties of QDs embedded glasses greatly hinder their commercial applications and the underlying mechanism has not been fully explored yet.…”

Section: Introductionmentioning

confidence: 91%

The defective nature of CdSe quantum dots embedded in inorganic matrices

et al. 2022

Preprint

Quantum dots (QDs) embedded in inorganic matrices have been extensively studied for their potential applications in lighting, displays, and solar cells. While a significant amount of research focused on its experimental fabrication, the origin of their relatively low photoluminescence quantum yield has not been investigated yet, although it severely hinders practical applications. In this work, we use time-dependent density functional theory (TDDFT) to pinpoint the nature of excited states of CdSe quantum dots embedded in various inorganic matrices. The formation of undercoordinated Se atoms and non-bridging oxygen atoms at QD/glass interface is responsible for the localization of a hole wavefunction, leading to the formation of low- energy excited states with weak oscillator strength. These states provide pathways for non-radiative processes and compete with radiative emission. The photoluminescence performance is predicted for CdSe quantum dots in different matrices, and validated by experiments. The results of this work have significant implications for understanding the underlying photophysics of CdSe quantum dots embedded in inorganic matrices that would facilitate the fabrication of highly luminescent glasses.