Nonradiative and radiative Förster energy transfer between quantum dots

Poddubny, Alexander N.; Rodina, A. V.

doi:10.1134/s1063776116030092

Cited by 25 publications

(13 citation statements)

References 42 publications

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“…The experimental results show that this certainly is not the case for the Si NC ensembles investigated here, with none of the nine samples adhering to this rule. Also the degradation of the PL QY upon high-energy excitation has been observed previously for colloidal PbS [16] and Si NCs, [13] among others. In the low-energy range, the PL QY for all the samples exhibits an initial increase with the excitation energy.…”

Section: Discussionsupporting

confidence: 70%

“…[2,12] The strength of the cooperative processes and their effect on the optical properties of an NC ensemble depend on the characteristics of the individual NCs themselves as well as on the ensemble properties, such as NC density and proximity, [13] confining potential of the embedding matrix [14] and its quality, etc. [2,12] The strength of the cooperative processes and their effect on the optical properties of an NC ensemble depend on the characteristics of the individual NCs themselves as well as on the ensemble properties, such as NC density and proximity, [13] confining potential of the embedding matrix [14] and its quality, etc.…”

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confidence: 99%

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Photoluminescence Quantum Yield in Ensembles of Si Nanocrystals

Chung

Limpens

Gregorkiewicz

2017

Advanced Optical Materials

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energy exchange with defects. [2,12] The strength of the cooperative processes and their effect on the optical properties of an NC ensemble depend on the characteristics of the individual NCs themselves as well as on the ensemble properties, such as NC density and proximity, [13] confining potential of the embedding matrix [14] and its quality, etc. [6] The cooperative processes typically involve an energy barrier for their activation, and therefore will change with the excitation energy. On the other hand, it is well known that the Kasha-Vavilov rule, [15] which states that the PL QY is independent of the excitation energy, is frequently violated for colloidal semiconductor NCs, [16] since carriers that are photogenerated higher in the conduction/ valence bands experience an increased probability of capturing at defect states and/or escape to the outside of an NC, leading to its ionization [10] and a temporal loss of optical activity. In result, the PL QY of the NCs decreases typically at short pump wavelengths. In this study, we investigate the excitation energy dependence of the PL QY for Si NC layers and find that it varies strongly in different samples. We investigate and discuss possible physical mechanisms influencing the PL QY at different excitation energies and conclude on an important role of impact excitation and parasitic absorption. Sample PreparationThe samples used in this study were produced by a co-sputtering method in the form of multilayer (ML) structures, featuring multiple stacks (up to 100) of 3.5 nm thin active layers of Si NCs separated by SiO 2 barriers. In this process, two sputtering guns, with Si and SiO 2 targets, are used. By operating both guns simultaneously, an Si-rich substoichiometric SiO x "active" layer can be grown, while solely the gun with silicon dioxide is applied to develop a barrier layer of pure SiO 2 . The atomic composition of the active layer can be tuned by adjusting the power of the guns, and the layer thickness is controlled by the exposure time. For the samples investigated in this study, the silicon excess of 15%, 25%, and 30% was used in the active layer. The barrier thickness between two adjacent active layers was set at 5 nm to avoid exciton diffusion between these layers. [17] Extensive past research [18,19] has shown that, in contrast to thick homogeneous layers of Si NCs in SiO 2 , ML structures allow for a better size control and therefore yield ensembles with a more narrow size distribution.This study investigates the photoluminescence quantum yield for cosputtered solid-state dispersions of Si nanocrystals in SiO 2 with different size and density, and concludes that the absolute value of the photoluminescence quantum yield shows a varied dependence on the excitation energy. Physical mechanisms influencing the photoluminescence quantum yield at different excitation energy ranges are considered. Based on the experimental evidence, this study proposes a generalized description of the excitation dependence of photoluminescence quantum yield of Si nanocrys...

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confidence: 70%

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confidence: 99%

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Photoluminescence Quantum Yield in Ensembles of Si Nanocrystals

Chung

Limpens

Gregorkiewicz

2017

Advanced Optical Materials

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“…42,43 To exclude that the shortening of the PL decay lifetimes observed here is solely due to the modification of the emission rate in the far field caused by the substrate, we evaluate the expressions of α ¼ α k and α ¼ 1 2 ðα k þ α ⊥ Þ for a pure dielectric substrate of permittivity εðInPÞ ¼ 12.493, which are shown in Fig. 6 together with the expression for the case of an ensemble of randomly oriented dipoles hαi ¼ 2 3 α k þ 1 3 α ⊥ (light blue curves).…”

Section: Discussionmentioning

confidence: 99%

Förster resonance energy transfer between individual semiconductor nanocrystals and an InP film

et al. 2016

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Abstract. The modification of the radiative decay of a single emitter in close vicinity to a dielectric interface is investigated by studying the photoluminescence (PL) decay dynamics of colloidal semiconductor nanocrystals (NCs) deposited on semiconductor surfaces. The PL decay lifetimes of single CdSe/CdS NCs spin-coated on InP surfaces passivated with thin oxide layers are measured. Electrochemical passivation of the InP surfaces with oxide layers of different thicknesses enables to study the influence of the distance between the semiconductor surface and the NC on the lifetime. A shortening of the PL decay lifetimes of the NCs with respect to their lifetimes on glass strongly suggests the opening of recombination channels for the photogenerated exciton, which we attribute to energy transfer between the NC and the semiconductor. We also experimentally show the influence of the orientation of the NC with respect to the semiconductor surface on the coupling.

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“…where τ D is the donor radiative lifetime in the presence of acceptor. The Förster radius, e.g., is 9 ± 2 nm in colloidal CdTe nanocrystal systems [30]; theoretically, it can approach 13 nm with τ 0 D 1 ns [39]. These values are comparable with the average distance between QDs at the 10 12 cm −2 lateral density.…”

Section: Competing Energy-transfer Mechanismsmentioning

confidence: 81%

Recombination dynamics in arrays of II-VI epitaxial quantum dots with Förster resonance energy transfer

Shubina

Pozina

Торопов

2016

Phys. Status Solidi B

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We report on time‐resolved photoluminescence (TR PL) studies of Förster resonance energy transfer (FRET) between epitaxial CdSe/ZnSe quantum dots (QDs). To prove the existence of FRET, we use two sheets of QD arrays, formed from CdSe insertions of different nominal thicknesses, which are separated by a ZnSe barrier of a variable width. The FRET mechanism manifests itself as acceleration of the PL decay of the energy‐donating QD sheet when the barrier width is decreased. The Förster radius of about 10.5 nm is determined by fitting TR PL data. Besides, our findings exhibit the inhomogeneous distribution of QD sizes within the QD arrays and the influence of FRET efficiency on recombination dynamics of forbidden exciton states. TR PL images showing the acceleration of PL decay of the energy‐donating QD array with decreasing the barrier width.

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Nonradiative and radiative Förster energy transfer between quantum dots

Cited by 25 publications

References 42 publications

Photoluminescence Quantum Yield in Ensembles of Si Nanocrystals

Photoluminescence Quantum Yield in Ensembles of Si Nanocrystals

Förster resonance energy transfer between individual semiconductor nanocrystals and an InP film

Recombination dynamics in arrays of II-VI epitaxial quantum dots with Förster resonance energy transfer

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