Synthesis of cubic CdSe nanocrystals and their spectral properties

Gao, Yukun; Yin, PG

doi:10.1177/1847980417701747

Cited by 9 publications

(4 citation statements)

References 24 publications

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“…Blue solid curves are the sum of all Lorentzians of Cd (i) Se (j) Table 1. Calculated Raman Peak Positions ω(D) (ij) of Lorentzian Peaks of Cd (i) Se (j) Bonds size (nm) ω(D) (41) ω(D (14) ω(D) (32) ω(D) (23) ω(D) (42) ω(D) (24) ω(D) (33) ω(D) (43) ω(D) (34) ω(D) Cd−X as surface bonds and other Cd−Se as interior bonds. 37 The Raman spectrum shows two broad peaks at ∼200 and ∼175 cm −1 at room temperature.…”

Section: Resultsmentioning

confidence: 99%

“…Silicon is a typical representative of nonpolar semiconductors, and II–VI compounds are a typical compound of polar semiconductors. II–VI semiconductor nanocrystals have been widely used in fields such as solar cells, light-emitting diodes, and bioluminescent labels. − ,, The Raman spectra of II–VI semiconductor nanocrystals have been extensively studied. − Their Raman spectra show a significant red shift compared to bulk crystals. Generally, the red shift is attributed to the phonon confinement effect.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Bond Dispersion on Raman Spectra Shift in II–VI Semiconductor Nanocrystals

Gao

Yin

2019

Inorg. Chem.

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To understand Raman spectra shifts of nanocrystals, the top-down phonon confinement approach and the bottom-up quantum chemical approach were developed. The former is suitable for large-sized nanocrystals, and the latter is suitable for clusters containing fewer atoms. Here, we find that a simpler chemical bond model based on the bond dispersion feature can demonstrate Raman spectra shift either in normal size II–VI semiconductor nanocrystals or in atomically precise clusters. According to the bond dispersion model, the Raman spectral line of the II–VI semiconductor nanocrystal (AIIBVI) is expressed as the sum of the Lorentz subpeaks of the AII(i)BVI(j) bonds with different coordinates i and j. The calculated Raman lines of CdSe, CdS, CdTe, ZnS, and ZnSe nanocrystals are in agreement with the measured Raman spectral lines. The origin of the red shift and asymmetric broadening of the peak position of nanocrystals may be revealed as well. Results provide insight into how different bonds contribute to different vibrational spectra.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of Bond Dispersion on Raman Spectra Shift in II–VI Semiconductor Nanocrystals

Gao

Yin

2019

Inorg. Chem.

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“…The perturbation approximation may become adequate in the case of small lateral size. According to the available data in the literature, the radius of the 3D exciton in CdSe is approximately 5–6 nm [ 56 , 57 , 58 ].…”

Section: Optical Transitions In Semiconductor Nanoplateletsmentioning

confidence: 99%

Exciton States and Optical Absorption in CdSe and PbS Nanoplatelets

et al. 2022

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The exciton states and their influence on the optical absorption spectrum of CdSe and PbS nanoplatelets (NPLs) are considered theoretically in this paper. The problem is discussed in cases of strong, intermediate, and weak size quantization regimes of charge carrier motion in NPLs. For each size quantization regime, the corresponding potential that adequately describes the electron–hole interaction in this mode of space quantization of charge carriers is chosen. The single-particle energy spectra and corresponding wave functions for strong intermediate and weak size quantization regimes have been revealed. The dependence of material parameters on the number of monolayers in the sample has been considered. The related selection rules and the dependence of the absorption coefficient on the frequency and polarization direction of the incident light wave were obtained. The interband transition threshold energy dependencies were obtained for each size quantization regime. The effect of dielectric coefficient mismatch and different models of electron–hole interaction potentials have been studied in CdSe and PbS NPLs. It is also shown that with an increase in the linear dimensions of the structure, the threshold frequency of absorption decreases. The binding energies and absorption coefficient results for NPL with different thicknesses agree with the experimental data. The values of the absorption exciton peaks measured experimentally are close to our calculated values for CdSe and PbS samples.

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“…We point out that the minimum in our ∆E XX is where the QD diameter is about the exciton Bohr radius. [57][58][59][60] When moving toward larger QDs from here, the two excitons will overlap less, approaching the bulk-like conditions. When the overlap of the excitons is decreased, the electron-electron and hole-hole repulsion decreases.…”

Section: The Biexciton Binding Energymentioning

confidence: 89%

Direct Visualization of Confinement and Many‐Body Correlation Effects in 2D Spectroscopy of Quantum Dots

Amarotti,

Wang,

Hedse

et al. 2024

Advanced Optical Materials

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The size tunable color of colloidal semiconductor quantum dots (QDs) is probably the most elegant illustration of the quantum confinement effect. As explained by the simple “particle‐in‐a‐box” model, the transition energies between the levels increase when the “box” becomes smaller. To investigate quantum confinement effects, typically a well‐defined narrow size distribution of the nanoparticles is needed. In this contribution, how coherent electronic two‐dimensional spectroscopy (2DES) can directly visualize the quantum size effect in a sample with broad size distribution of QDs is demonstrated. The method is based on two features of the 2DES – the ability to resolve inhomogeneous broadening and the capability to reveal correlations between the states. In QD samples, inhomogeneous spectral broadening is mainly caused by the size distribution and leads to elongated diagonal peaks of the spectra. Since the cross peaks correlate the energies of two states, they allow drawing conclusions about the size dependence of the corresponding states. It is also found that the biexciton binding energy changes between 3 and 8 meV with the QD size. Remarkably, the size dependence is non‐monotonic with a clear minimum.

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Synthesis of cubic CdSe nanocrystals and their spectral properties

Cited by 9 publications

References 24 publications

Effect of Bond Dispersion on Raman Spectra Shift in II–VI Semiconductor Nanocrystals

Effect of Bond Dispersion on Raman Spectra Shift in II–VI Semiconductor Nanocrystals

Exciton States and Optical Absorption in CdSe and PbS Nanoplatelets

Direct Visualization of Confinement and Many‐Body Correlation Effects in 2D Spectroscopy of Quantum Dots

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