Exciton states of II–VI tetrapod-shaped nanocrystals

Ya, Yao; Kuroda, Takashi; Dirin, Dmitry N.; Irkhina, A.; Vasiliev, R. B.; Sakoda, Kazuaki

doi:10.1364/ome.3.000977

Cited by 5 publications

(8 citation statements)

References 51 publications

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“…The tetrapod-shaped NCs also attracted the interest of the theoretical investigations, which include calculation of the one-particle states of bare tetrapods by the semiempirical pseudopotential method [5,29] and effective mass approximation [10,38] as well as the calculation of exciton states by Hartree approximation [8,7,6]. We recently calculated the exciton states of II-VI bare tetrapods using a configuration interaction approach and obtained a good agreement with reported experimental data [9,37].…”

Section: Introductionmentioning

confidence: 74%

Strain effects on optical properties of tetrapod-shaped CdTe/CdS core–shell nanocrystals

Kuroda

Dirin

et al. 2014

Superlattices and Microstructures

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The exciton states of strained CdTe/CdS core-shell tetrapod-shaped nanocrystals were theoretically investigated by the numerical diagonalization of a configuration interaction Hamiltonian based on the single-band effective mass approximation. We found that the inclusion of strain promotes the type-II nature by confining the electrons and holes in nonadjacent regions. This carrier separation is more efficient than that with type-II spherical nanocrystals. The strain leads to a small blue shift of the lowest exciton energy. Its magnitude is smaller than the red shift induced by increasing the shell thickness. Moreover, the larger arm diameter reduces the influence of both shell thickness and strain on the exciton energy. Considering the broken symmetry, a randomness induced carrier separation was revealed which is unique to a branched core-shell structure. The calculated shell thickness dependence of the emission energy agrees well with available experimental data.

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Section: Introductionmentioning

confidence: 74%

Strain effects on optical properties of tetrapod-shaped CdTe/CdS core–shell nanocrystals

Kuroda

Dirin

et al. 2014

Superlattices and Microstructures

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“…However, due to the small energy difference between these lowest T 2 excitons and the lowest one photon optically-active A 1 excitons the room-temperature thermal energy mixes the population of these two exciton states, and luminescence from the A 1 exciton level must be observed. 31 As the CdS tetrapods show a similar symmetry to tetrahedral QDs, the reduced DOS can be expected at the particle arms, which together with theoretically shown confinement of excitons inside the core region suggests that mainly the cores of CdS tetrapods contribute to the TPA strength. This is likely to be the case since the peak s 2 value for CdS tetrapods is close to those measured for 4-5 nm spherical CdS QDs ( Table 1).…”

Section: Methodsmentioning

confidence: 89%

“…The wave function of the lowest twenty electron and hole states, which govern the optical properties of tetrapodlike shaped semiconducting nanoparticles, was also found to be strongly confined to a small central-core region. 31 The dimensions of CdS tetrapods, and the density of bulk CdS (4.83 g cm À3 ), were used to estimate the molecular weight (MW) of a single particle. The volume of a single CdS tetrapod was calculated as a sum of the volume of the tetrahedron core and four pyramid arms.…”

Section: Methodsmentioning

confidence: 99%

“…2c) can be to some extent based on the theoretical calculations reported by V. A. Fonoberov et al, 39 and the calculations of individual electron + hole and exciton states in semiconducting type II-VI tetrapod-shaped nanocrystals. 30,31 The former 39 investigated the exciton states and optical transition in colloidal CdS QDs with spherical and tetrahedral shapes. The authors have shown that the electron and hole densities near the edges and vertices of tetrahedra are extremely small, and that it is the core of the QD that mainly contributes to the observed optical transitions.…”

Section: Methodsmentioning

confidence: 99%

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Two-photon absorption in penicillamine capped CdS tetrapods

Wawrzyńczyk

2017

J. Mater. Chem. C

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“…With Tps, electron transport could be achieved perpendicularly to the plane of a device . The arms of Tps could be wired out to fabricate a single NC transistor, and the intracrystal charge-transfer characteristic could improve the efficiency of solar cells and enhance the photocatalytic activity. − With four arms, it is easier to self-assemble into hierarchical (chiral) networks with improved electrical and optical properties. , …”

Section: Introductionmentioning

confidence: 99%

Chiral 3D CdSe Nanotetrapods

Shao

Jiang

et al. 2020

Inorg. Chem.

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Three-dimensional (3D) nanomaterials have been intensively investigated because of their unique properties and wide range of potential applications; however, the ligand-induced chirality in 3D semiconductor nanocrystals has been scarcely studied. In this paper, we report the synthesis of hydrophobic 3D CdSe nanotetrapods (Tps) with a high degree of uniformity in their morphology by using the hot-injection method. The core and arms of Tps are distinct in their crystal structure, thus creating an intracrystal heterojunction. The size of Tps, primarily the length of four arms, is controlled by changing the amount of didecyldimethylammonium bromide and reaction time. Next, enantiopure cysteine ligands were introduced to replace the hydrophobic native stabilizers to prepare chiral l- and d-cysteine-capped CdSe Tps. Importantly, the circular dichroism (CD) line shapes of l/d-cysteine-capped CdSe Tps are assigned to the different excitonic transitions of the core and arms, respectively. In addition, the observed CD activities are found to be sensitive to the size of the CdSe Tps, where the anisotropic g factors have increased and reached the maximum value at a moderate aspect ratio (AR) and a further increase of the AR leads to a decrease of the g factor. Because of charge transfer between the core and arms, we propose a plausible mechanism potentially responsible for the induced CD line shapes in terms of the excitonic states of Tps with two different crystal structures. We believe that chiral 3D nanomaterials with anisotropic morphologies could offer new opportunities for relevant applications.

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Exciton states of II–VI tetrapod-shaped nanocrystals

Cited by 5 publications

References 51 publications

Strain effects on optical properties of tetrapod-shaped CdTe/CdS core–shell nanocrystals

Strain effects on optical properties of tetrapod-shaped CdTe/CdS core–shell nanocrystals

Two-photon absorption in penicillamine capped CdS tetrapods

Chiral 3D CdSe Nanotetrapods

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