Dilution effects on the photoluminescence of ZnSe quantum-dot dispersions

Mei, Bingchu; Wang, Jun; Qiu, Qi; Heckler, Tracy; Petrou, A.; Mountziaris, T. J.

doi:10.1063/1.2970995

Cited by 21 publications

(7 citation statements)

References 22 publications

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“…Others have also observed this phenomenon in CdSe and ZnSe QDs. 19,20 In addition to increasing the QY of the QDs, dilution causes the band-edge transition of the QDs to shift to higher energies by 3.5 nm over the range of concentrations we explored (see Supporting Information). The QY of colloidal QDs is highly sensitive to the chemical conditions at their surfaces.…”

Section: Articlementioning

confidence: 98%

Model for Adsorption of Ligands to Colloidal Quantum Dots with Concentration-Dependent Surface Structure

Morris-Cohen¹,

Vasilenko²,

Amin³

et al. 2011

ACS Nano

100

165

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A study of the adsorption equilibrium of solution-phase CdS quantum dots (QDs) and acid-derivatized viologen ligands (N-[1-heptyl],N'-[3-carboxypropyl]-4,4'-bipyridinium dihexafluorophosphate, V(2+)) reveals that the structure of the surfaces of the QDs depends on their concentration. This adsorption equilibrium is monitored through quenching of the photoluminescence of the QDs by V(2+) upon photoinduced electron transfer. When modeled with a simple Langmuir isotherm, the equilibrium constant for QD-V(2+) adsorption, K(a), increases from 6.7 × 10(5) to 8.6 × 10(6) M(-1) upon decreasing the absolute concentration of the QDs from 1.4 × 10(-6) to 5.1 × 10(-8) M. The apparent increase in K(a) upon dilution results from an increase in the mean number of available adsorption sites per QD from 1.1 (for [QD] = 1.4 × 10(-6) M) to 37 (for [QD] = 5.1 × 10(-8) M) through desorption of native ligands from the surfaces of the QDs and through disaggregation of soluble QD clusters. A new model based on the Langmuir isotherm that treats both the number of adsorbed ligands per QD and the number of available binding sites per QD as binomially distributed quantities is described. This model yields a concentration-independent value for K(a) of 8.7 × 10(5) M(-1) for the QD-V(2+) system and provides a convenient means for quantitative analysis of QD-ligand adsorption in the presence of competing surface processes.

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Section: Articlementioning

confidence: 98%

Model for Adsorption of Ligands to Colloidal Quantum Dots with Concentration-Dependent Surface Structure

Morris-Cohen¹,

Vasilenko²,

Amin³

et al. 2011

ACS Nano

100

165

View full text Add to dashboard Cite

show abstract

“…It has long been recognized that there is a blue shift of the photoluminescence wavelength for QDs of smaller crystalline size. A formula [34], l g Àl=l g ¼ c lnðd c =dÞ, was employed to estimate the ZnSe nanoparticles size from the PL wavelength, where l g ( ¼460 nm) is the band gap emission wavelength from bulk ZnSe, d c (¼9 nm) is the quantum confinement threshold for ZnSe, and C( ¼0.128) is an empirical unitless constant. Similarly, the same formula could be applied to estimate the size of ZnMnSe, as listed in Table 1.…”

Section: R E T R a C T E Dmentioning

confidence: 99%

RETRACTED: Investigation on manganese-doped ZnSe QDs prepared from self-assembled template of reverse micelle

Qiu

Heckler

Wang

et al. 2010

Journal of Luminescence

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“…When dealing with a QD solution, there is an additional dilution and quenching effect. [23] That means at higher QD concentration, there will be higher reabsorption and a reduction of the emission. To model the quenching effect, the expression of the measured intensity is revised accordingly…”

Section: Resultsmentioning

confidence: 99%

Restriction‐In‐Motion of Surface Ligands Enhances Photoluminescence of Quantum Dots—Experiment and Theory

Fang

Shih

et al. 2022

Adv Materials Inter

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molecular processes within individual cells, [1] they present challenges, especially in maintaining their fluorescence properties after exposure to the excitation light for a period of time. Generally, it is well known that commonly employed organic fluorophores suffer from photobleaching, low quantum yields, and aggregationinduced self-quenching, some of which can be attributed to the organic nature of these fluorophores.One class of nonorganic fluorophores with promising optical properties are quantum dots (QDs), which are semiconductor nanocrystals. QDs have nanoscale dimensions, small enough to induce quantum confinement. [2] This unique characteristic allows for manipulating QDs' fluorescent properties for specific applications by changing their sizes. [3] The optical properties of QDs include broad and continuous absorption spectra, narrow and symmetric emission spectra, high photochemical stability, and the ability to emit a tunable size-specific color that depends on the adjustable bandgap of the semiconductor core. [4] Compared to conventional fluorophores, QDs have higher quantum yield and reduced susceptibility to photobleaching, thus allowing for extendedThe relationship between emission and ligand restriction of a series of ZnSe/ ZnS quantum dots (QDs) encapsulated in nanoparticles is investigated systematically via experiments and quantum theory. The QDs have a ZnSe core and a ZnS shell, capped with hydrophobic ligands (triotylphosphine oxide/ hexadecylamine), allowing them to be entrapped in a model biomembrane, bicelle, made of zwitterionic dipalmitoyl and dihexanoyl phosphatidylcholines and charged dipalmitoyl phosphatidylglycerol. Enhanced photoluminescence is observed upon encapsulation, depending on the QD-to-lipid ratio. Transmission electron microscopy and small-angle X-ray scattering confirm that QDs are preferably situated at the rim of bicellar discs. A simplified quantum dissipation heat-bath theory is proposed to correlate the enhancement with slower nonradiative processes caused by the restriction-in-motion (RIM) of the surface ligands. However, Förster resonance energy transfer due to QD aggregation counteracts the effect.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/admi.202102079.

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Dilution effects on the photoluminescence of ZnSe quantum-dot dispersions

Cited by 21 publications

References 22 publications

Model for Adsorption of Ligands to Colloidal Quantum Dots with Concentration-Dependent Surface Structure

Model for Adsorption of Ligands to Colloidal Quantum Dots with Concentration-Dependent Surface Structure

RETRACTED: Investigation on manganese-doped ZnSe QDs prepared from self-assembled template of reverse micelle

Restriction‐In‐Motion of Surface Ligands Enhances Photoluminescence of Quantum Dots—Experiment and Theory

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