Photoluminescence dynamics in solid formulations of colloidal PbSe quantum dots: Three-dimensional versus two-dimensional films

Quintero-Torres, Rafael; Foell, Charles; Pichaandi, Jothirmayanantham; Veggel, Frank C. J. M. van; Young, Jeff F.

doi:10.1063/1.4752737

Cited by 11 publications

(7 citation statements)

References 27 publications

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“…The fact that oxidation is only contributing but not the dominant factor leading to changes in the optical properties of lead chalcogenides solids is also reported by Quintero-Torres et al 34 In framework of this model ones can expect a decreasing the average PL lifetimes with the degradation of the QD surface passivation. To check this fact, we measured PL lifetimes for samples with QDs with diameter 4.0 and 7.4 nm after 30 day storage.…”

Section: ■ Introductionsupporting

confidence: 69%

“…5 This type of surface passivation is not efficient in case of dry QD solids and leads to degradation of optical properties of QDs in particular due to oxidation of QD. 34 If oxidation is a prevailing process, it results in decreasing of QD size and blue-shifts in absorption and emission spectra. Numerous efforts have been made to improve the stability of PbS QD systems.…”

Section: ■ Introductionmentioning

confidence: 99%

“…QDs of this type are usually capped by organic passivating agents such as oleic acid and trioctylphosphine . This type of surface passivation is not efficient in case of dry QD solids and leads to degradation of optical properties of QDs in particular due to oxidation of QD . If oxidation is a prevailing process, it results in decreasing of QD size and blue-shifts in absorption and emission spectra.…”

Section: Introductionmentioning

confidence: 99%

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PbS Quantum Dots in a Porous Matrix: Optical Characterization

et al. 2013

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We propose simple and practical method for creation of quantum dot (QD) systems in a porous matrix. The commercial filter paper is soaked in the colloidal solution of PbS QDs in carbon tetrachloride followed by drying. The samples prepared by the method demonstrate linear dependencies of optical density and photoluminescence intensity on the QD concentration, excellent homogeneity, and reproducibility. A red-shift of QD photoluminescence spectrum after their infiltration into the matrix and energy transfer between QDs of different sizes indicate formation of the close-packed QD system. Optical properties and stability of the close-packed PbS quantum dot systems are investigated at room temperature in a wide range of QD sizes. A strong reduction of average QD photoluminescence lifetime from 435 to 55 ns with decreasing QD diameter from 3.0 to 7.4 nm has been found. A blue-shift of the photoluminescence spectra accompanied by increasing the photoluminescence lifetime observed for small and medium QDs with the sample storage indicates decreasing the QD size due to oxidation of their surface.

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Section: ■ Introductionsupporting

confidence: 69%

Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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PbS Quantum Dots in a Porous Matrix: Optical Characterization

et al. 2013

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“…However, Figure clearly shows that most of this increase in efficiency is due to the reduced long-time exciton population decay rate at lower temperatures. On the basis of other work on similar samples, ,, we attribute this temperature dependence of the long time constant to a reduced nonradiative recombination rate at lower temperatures, owing to its activated nature.…”

Section: Discussionmentioning

confidence: 60%

Temperature Dependence of Förster Thermalization and Population Decay in PbSe Nanocrystals

Quintero-Torres¹,

Veggel

Young

2013

J. Phys. Chem. C

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Time-resolved photoluminescence spectroscopy is used to quantify the Forster-mediated exciton migration rate and the exciton population decay rate in drop-cast solid emulsions of PbSe colloidal nanocrystals emitting near 1.5 μm from 77 to 300 K. For both unimodal and bimodal emulsions, at a fixed temperature in a given sample the measured time constants that characterize the fast transient decay (blue side of the spectrum) and buildup (red side of the spectrum) vary considerably with emission wavelength, but the average fast time constant, ∼25 ns, varies little (i.e., within <25%) with temperature from 77 to 300 K. Over the same temperature range, the exciton population lifetime, ascribed to nonradiative decay, decreases by ∼5 times but is always longer than the Forster time constant. The increase of the Forster-mediated efficacy of exciton redistribution at low temperatures before they decay is therefore almost all due to the variation of the nonradiative decay rate. By analyzing the temporally resolved and steady-state emission spectra, it is noted that the time required for the exciton population to equilibrate is nonexponential and considerably longer (∼150 ns) than the rapid decay and buildup time constants extracted from the decay curves at fixed wavelengths.

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“…As mentioned above, the QY of the PbS/CdS QDs in tetrachloroethylene dispersions used here was determined at 0.37. In general, this QY goes down after Langmuir-Blodgett deposition on silicon [29,30], such that the value of 0.37 should be seen as an upper limit. For determining η coupling , we use an FDTD numerical solver to determine the fraction of the power emitted by a dipole oscillator that is coupled to the waveguide modes.…”

Section: Contribution Of the Qd Pbs/cds Core Shell Emission To The Mementioning

confidence: 99%

Light absorption in hybrid silicon-on-insulator/quantum dot waveguides

Omari¹,

Geiregat²,

Thourhout³

et al. 2013

Opt. Express

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We analyze the absorption coefficient of planarized silicon-on-insulator waveguides coated by close packed mono- and multilayers of colloidal PbS/CdS quantum dots (QDs). Experimental data clearly show the influence of the QDs on the waveguide absorbance around 1500 nm, where we find that QDs absorb stronger in thicker layers. To simulate the absorption coefficient of QD functionalized waveguides, the QD layer is replaced by an effective medium with a dielectric function determined by dipolar coupling between neighbouring QDs. Using the host dielectric constant εh as an adjustable parameter, excellent agreement with the experimental results is obtained. In this way, the increase in absorption cross section with layer thickness can be traced back to an increasing εh. We argue that this reflects the decreasing influence of the surroundings on the εh, which therefore evolves from an extrinsic property for monolayers to a more intrinsic film property for multilayers.

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Photoluminescence dynamics in solid formulations of colloidal PbSe quantum dots: Three-dimensional versus two-dimensional films

Cited by 11 publications

References 27 publications

PbS Quantum Dots in a Porous Matrix: Optical Characterization

PbS Quantum Dots in a Porous Matrix: Optical Characterization

Temperature Dependence of Förster Thermalization and Population Decay in PbSe Nanocrystals

Light absorption in hybrid silicon-on-insulator/quantum dot waveguides

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