Thermal expansion of colloidal CdSe/CdS core/shell quantum dots

Badlyan, Narine Moses; Biermann, Amelie; Aubert, Tangi; Hens, Zeger; Maultzsch, Janina

doi:10.1103/physrevb.99.195425

Cited by 4 publications

(5 citation statements)

References 32 publications

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“…The first term E 0 is the intrinsic material band-gap at T = 0, and the coefficient A in the second term characterizes the change in band-gap due to lattice unit cell expansion/contraction (in the so-called quasi-harmonic approximation 24 ). Here the change in quantum confinement energy due to expansion/contraction of nanocrystal volume, which we expect to be negligible at low temperatures 25 , is ignored. The third term then represents renormalization of the band-gap due to electron-phonon interactions, where n is summed over all phonon branches and all wave-vectors within the Brillouin zone for each branch.…”

Section: Results and Discusssionmentioning

confidence: 99%

Effect of dimensionality on the optical absorption properties of CsPbI3 perovskite nanocrystals

Liu

Bonato

Sessa

et al. 2019

The Journal of Chemical Physics

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The band-gaps of CsPbI 3 perovskite nanocrystals are measured by absorption spectroscopy at cryogenic temperatures. Anomalous band-gap shifts are observed in CsPbI 3 nanocubes and nanoplatelets, which are modeled accurately by band-gap renormalization due to lattice vibrational modes. We find that decreasing dimensionality of the CsPbI 3 lattice in nanoplatelets greatly reduces electron-phonon coupling, and dominant out-of-plane quantum confinement results in a homogeneously broadened absorption lineshape down to cryogenic temperatures. An absorption tail forms at lowtemperatures in CsPbI 3 nanocubes, which we attribute to shallow defect states positioned near the valence band-edge.

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Section: Results and Discusssionmentioning

confidence: 99%

Effect of dimensionality on the optical absorption properties of CsPbI3 perovskite nanocrystals

Liu

Bonato

Sessa

et al. 2019

The Journal of Chemical Physics

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“…The energy of the electron without impurity remains positive, corresponding to the electron in the bulk material. We have plotted the range of the half-width from 3 nm to 12 nm, corresponding to the experimentally obtained core/shell CdSe/CdS QD [38]. As the size of the QD decreases, the positive contribution of the QD walls to the binding energy increases, and in parallel, as the electron becomes closer to impurity, the negative contribution to the binding energy increases.…”

Section: Theorymentioning

confidence: 99%

Linear and Nonlinear Optical Absorption of CdSe/CdS Core/Shell Quantum Dots in the Presence of Donor Impurity

Mantashian

Zaqaryan

Mantashyan

et al. 2021

Atoms

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Linear and nonlinear optical properties in colloidal CdSe/CdS core/shell quantum dots with different sizes have been theoretically investigated in the framework of effective mass approximation. The electron states in colloidal CdSe/CdS core/shell quantum dots have been calculated using the finite element method. The intraband linear and nonlinear absorption spectra have been calculated for colloidal CdSe/CdS core/shell quantum dots with different sizes. In addition, the dependences of the linear and nonlinear refractive index change on the incident light energy have been calculated. In the last section of the paper the second- and third-order harmonic generation spectra have been presented.

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“…Although descriptions of the CdSe@CdS core@shell structure have been reported in the literature, most of the information was derived from the size change of the nanocrystals compared with core QDs and the synthetic process. [ 24 , 25 ] For example, Li et al [ 20 ] synthesized high‐quality CdSe@CdS core@shell QDs using the successive ionic layer adsorption and reaction (SILAR) approach and achieved precise control of the shell thickness. Up to now, the interface between CdSe core and CdS shell in the CdSe@CdS QDs has not been identified at the atomic level.…”

Section: Introductionmentioning

confidence: 99%

Atomic Identification of Interfaces in Individual Core@shell Quantum Dots

et al. 2021

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CdSe@CdS Core@shell quantum dots (QDs) have been widely studied in recent years, due to their architecture which allows to tailor properties by controlling structure and composition. However, since CdSe and CdS have the same crystal structure, same cations, and similar lattice parameters, it is very challenging to image the interface. Herein, high-resolution transmission electron microscopy, high-angle annular dark-field imaging, and energy-dispersive X-ray spectroscopy elemental mapping are combined to characterize the core@shell structure and identify the interface in the CdSe@CdS QDs with different CdS shell thicknesses. By examining changes in lattice spacing in an individual CdSe@CdS quantum dot, the atomic core@shell interface is identified. For thin-shelled QDs, an ideal coherent interface forms between core and shell due to the small lattice mismatch, and the lattice spacing remains unchanged at the core and shell regions. For thick-shelled QDs, the lattice spacing is different at the core and shell regions, while the heterostructured interface is still coherent and cannot be clearly imaged. As the shell thickness further increases, a sharp core@shell interface appears. The results define an approach to characterize the heterostructure of two materials with the same crystalline structure and cations.

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Thermal expansion of colloidal CdSe/CdS core/shell quantum dots

Cited by 4 publications

References 32 publications

Effect of dimensionality on the optical absorption properties of CsPbI3 perovskite nanocrystals

Effect of dimensionality on the optical absorption properties of CsPbI3 perovskite nanocrystals

Linear and Nonlinear Optical Absorption of CdSe/CdS Core/Shell Quantum Dots in the Presence of Donor Impurity

Atomic Identification of Interfaces in Individual Core@shell Quantum Dots

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