Exciton transitions in tetrapod-shaped CdTe nanocrystals investigated by photomodulated transmittance spectroscopy

Tarì, D.; Giorgi, Milena De; Pompa, Pier Paolo; Carbone, Luigi; Manna, Liberato; Kudera, Stefan; Cingolani, R.

doi:10.1063/1.2335801

Cited by 10 publications

(9 citation statements)

References 35 publications

(17 reference statements)

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“…The first three confined states in the conduction and valence bands for sample A3 are shown in Figure 4. As in the case of all-CdTe tetrapods, 23 we found that, in the ground-state (GS) exciton, the electron density (Figure 4a) is mostly localized in the CdSe core region of the tetrapods, whereas the electron wave function spreads into the arms for the first excited state (1ES, Figure 4b), until it becomes completely delocalized into the arms for the second excited state (2ES, Figure 4c). On the other hand, the holes of the first three confined states are completely delocalized in the CdTe arms (Figure 4dÀf).…”

Section: ' Morphological Characterizationsupporting

confidence: 56%

Temperature and Size Dependence of the Optical Properties of Tetrapod-Shaped Colloidal Nanocrystals Exhibiting Type-II Transitions

et al. 2011

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We have investigated the optical properties of colloidal seed-grown CdSe (seed)/CdTe (arms) nanotetrapods both experimentally and computationally. The tetrapods exhibit a type-II transition arising from electrons localized in the CdSe seed region and holes delocalized in the CdTe arms, along with a residual type-I recombination in long-arm tetrapods. Experiments and theory helped to identify the origin of both types of transitions and their size dependence. In particular, time-resolved experiments performed at 10 K evidenced a size-dependent, long living type-II radiative emission arising from the peculiar electron hole wave function localization. Temperature-dependent photoluminescence (PL) studies indicate that, at high temperature (>150 K), the main process limiting the PL quantum efficiency of the type-I PL is thermal escape of the charge carriers through efficient exciton-optical phonon coupling. The type-II PL instead is limited both by thermal escape and by the promotion of electrons from the conduction band of the seed region to that of the arms, occurring at T > 200

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Section: ' Morphological Characterizationsupporting

confidence: 56%

Temperature and Size Dependence of the Optical Properties of Tetrapod-Shaped Colloidal Nanocrystals Exhibiting Type-II Transitions

et al. 2011

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“…5 Besides sphericalshaped quantum dots ͑QDs͒, other materials with more exotic shapes and compositions have been fabricated and studied optically. 2,6,7 One of the most intriguing nanostructures is based on the growth of a CdS rodlike shell onto a spherical CdSe QD. [8][9][10] Previous studies 11,12 show that in such a system carriers might experience different types of localization, since the hole remains confined inside the CdSe dot, whereas the electron is completely delocalized throughout the CdS nanorod.…”

Section: Introductionmentioning

confidence: 99%

Intrinsic optical nonlinearity in colloidal seeded grown CdSe/CdS nanostructures: Photoinduced screening of the internal electric field

et al. 2008

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The assessment of the presence and the origin of an intrinsic internal electric field in novel colloidal CdSe/CdS nanoheterostructures is of fundamental importance in order to understand their optical properties, due to both their impact on the basic research fields, and their potential in technological applications. To this aim, a deep study of the carrier dynamics in spherical ͑quantum dots͒ and rod-shaped ͑nanorods͒ colloidal seeded grown CdSe/CdS nanocrystals via time-resolved photoluminescence spectroscopy has been carried out in this report. A transient, power-dependent redshift of the spectra is observed. An optical nonlinearity is also found by continuous-wave photoluminescence measurements on ensemble and single nanostructures, which is attributed to a photoinduced screening of an internal field. This internal field could originate from the intrinsic piezoelectric polarization, which is a typical effect in strained heterostructures with a lattice mismatch greater than 3.9%. Our theoretical calculations support the experimental results.

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“…Gao and Wang grew CdS nanobelts by using a thermal evaporation method [21]. They used a CVD setup to grow CdS nanobelts via vapor-liquidsolid (VLS) by the assistance of gold as metal catalyst and vapor-solid (VS) Exciton Bohr radius 3 nm [11] 6 nm [12] 7.3 nm [13] Exciton binding energy 28 meV [14] 13 meV [15] 25 meV [16] Electron effective mass 0.25 m e [17] 0.45 m e [18] 0.095 m e [17] Table 9.1 Selective material parameters of CdEs [10]. (Continued) process.…”

Section: Thermal Evaporation Methods To Grow Cd-chalcogenide Nanocrystalsmentioning

confidence: 99%

“…16 Typical SEM, TEM, and HRTEM images of Bi-catalyzed (a-c) CdTe and (d-f) CdS nanowires. Reprinted with permission from Ref [38]…”

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Metal Chalcogenide Hierarchical Nanostructures for Energy Conversion Devices

Yousefi

Jamali‐Sheini

Zak

2014

Metal Chalcogenide Nanostructures for Renewable Energy Applications

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Metal chalcogenide hierarchical nanostructures as energy conversion devices were studied in this chapter. Cd-chalcogenide nanostructures were chosen as sample study due to their unique properties as energy converter. In the first step, different methods were introduced to grow this type of nanostructures. It was discussed three low cost-effective methods to grow the Cd-chalcogenide nanostructures such as thermal evaporation (chemical and physical vapor depositions), chemical bath deposition, and electrochemical methods. However, it was observed that samples were grown by a pulsed laser deposition method as a complex method. In addition, effects of growth conditions on morphology and optical properties of the nanostructures were investigated. In the second step, the fundamentals of solar energy conversion were described. Furthermore, quantum physics of semiconductor solar cells was studied. Finally, the Cd-chalcogenide nanostructures were introduced as solar energy conversion and important factors that can affect the efficiency of this type of solar cells were introduced.

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Exciton transitions in tetrapod-shaped CdTe nanocrystals investigated by photomodulated transmittance spectroscopy

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Cited by 10 publications

References 35 publications

Temperature and Size Dependence of the Optical Properties of Tetrapod-Shaped Colloidal Nanocrystals Exhibiting Type-II Transitions

Temperature and Size Dependence of the Optical Properties of Tetrapod-Shaped Colloidal Nanocrystals Exhibiting Type-II Transitions

Intrinsic optical nonlinearity in colloidal seeded grown CdSe/CdS nanostructures: Photoinduced screening of the internal electric field

Metal Chalcogenide Hierarchical Nanostructures for Energy Conversion Devices

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