Nature of electronic excitations in small non-stoichiometric quantum dots

Bhati, Manav; Ivanov, Sergei A.; Senftle, Thomas P.; Tretiak, Sergei; Ghosh, Dibyajyoti

doi:10.1039/d1ta07983b

Cited by 16 publications

(30 citation statements)

References 72 publications

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“…However, if the lowest-energy states are optically weak (small oscillator strength) or even completely inactive, it takes much longer for radiative emission; in this case, nonradiative processes can take place and even quench the emission. Therefore, the oscillator strength of the lowest-energy transition (which is inversely proportional to the radiative time) could be used as an indicator of the emission efficiency of the QDs. , In terms of experimental characterization, the PLQY is a common index to represent emission efficiency. Therefore, based on our calculations, the PLQY of the glasses is expected to decrease in the order of Q25N75S, Q20N5C75S, Q15N5C75S, and Q33N67S according to the oscillator strength of the first excited-state transition.…”

Section: Resultsmentioning

confidence: 99%

“…Instead, molecular simulations have proven to be a reliable approach to investigate the atomic and electronic structures of colloidal QDs. Atomistic modeling methods were used for the characterization of the ground state − and excited states − of CdSe QDs. These theoretical studies investigated the origin of defect emission of colloidal QDs and provide a better understanding of QDs’ photophysics, giving guidance to the experimental design of novel materials, for example, using the passivation method.…”

Section: Introductionmentioning

confidence: 99%

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Defective Nature of CdSe Quantum Dots Embedded in Inorganic Matrices

Zhao

et al. 2022

J. Am. Chem. Soc.

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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.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Defective Nature of CdSe Quantum Dots Embedded in Inorganic Matrices

Zhao

et al. 2022

J. Am. Chem. Soc.

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“…Therefore, the oscillator strength of the lowest-energy transition (which is inversely proportional to the radiative time) could be used as an indicator of the emission efficiency of the QDs. 27,31 In terms of experimental characterization, the PLQY is a common index to represent emission efficiency.…”

Section: Resultsmentioning

confidence: 99%

“…The Se-rich CdSe QD was found to have poor photoluminescence performance compared to Cd-rich CdSe QD and stoichiometric QDs. 31 It is worthy of considering this imperfect QD embedded in glasses and the semiconductor material is not limited to CdSe, PbS or perovskite QD.…”

Section: Discussionmentioning

confidence: 99%

“…Instead, molecular simulations have proven to be a reliable approach to investigate the atomic and electronic structure of colloidal QDs. Atomistic modelling methods were used for the characterization of the ground state [22][23][24][25] as well as excited states [26][27][28][29][30][31][32][33][34][35][36] of CdSe QDs. Those theoretical studies investigated the origin of defect emission of colloidal QDs and provide a better understanding of QDs photophysics, giving guidance to the experimental design of novel materials, e.g., by the passivation method.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The defective nature of CdSe quantum dots embedded in inorganic matrices

Zhao

et al. 2022

Preprint

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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.

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