Alloyed Semiconductor Quantum Dots:  Tuning the Optical Properties without Changing the Particle Size

Bailey, Robert E.; Nie, Shuming

doi:10.1021/ja035000o

Cited by 901 publications

(757 citation statements)

References 59 publications

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“…S1) and photoluminescence quantum yields of 41 and 90%. These values are in line with earlier reports on gradient alloy QDots, reaching very high PLQY compared to more classical coreeshell structured QDots [30]. The two types of QDots were therefore further defined as QDot500 and QDot600.…”

Section: Nanoparticle Characterizationsupporting

confidence: 87%

“…Gradient alloy QDots consist out of a gradient internal structure (e.g. cadmium zinc selenide) which in contrast to particles with a homogeneous structure enables to achieve a fine tuning of the optical properties of the QDots without having to change particle size [30]. By modifying this gradient, gradient alloy QDots of the same size have been generated that can emit in the entire visible range [31].…”

Section: Introductionmentioning

confidence: 99%

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The performance of gradient alloy quantum dots in cell labeling

Soenen¹,

Manshian²,

Himmelreich³

et al. 2014

Biomaterials

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The interest in using quantum dots (QDots) as highly fluorescent and photostable nanoparticles in biomedicine is vastly increasing. One major hurdle that slows down the (pre)clinical translation of QDots is their potential toxicity. Several strategies have been employed to optimize common coreshell QDots, such as the use of gradient alloy (GA)-QDots. These particles no longer have a sizedependent emission wavelength, but the emission rather depends on the chemical composition of the gradient layer. Therefore, particles of identical sizes but with emission maxima spanning the entire visible spectrum can be generated. In the present study, two types of GA-QDots are studied with respect to their cytotoxicity and cellular uptake. A multiparametric cytotoxicity approach reveals concentration-dependent effects on cell viability, oxidative stress, cell morphology and cell functionality (stem cell differentiation and neurite outgrowth), where the particles are very robust against environmentally-induced breakdown. Non-toxic concentrations are defined and compared to common core-shell QDots analyzed under identical conditions. Additionally, this value is translated into a functional value by analyzing the potential of the particles for cell visualization. Interestingly, these particles result in clear endosomal localization, where different particles result in identical intracellular distributions. This is in contrast with CdTe QDots with the same surface coating, which resulted in clearly distinct intracellular distributions as a result of differences in nanoparticle diameter.The GA-QDots are therefore ideal platforms for cell labeling studies given their high brightness, low cytotoxicity and identical sizes, resulting in highly similar intracellular particle distributions which offer a lot of potential for optimizing drug delivery strategies.

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Section: Nanoparticle Characterizationsupporting

confidence: 87%

Section: Introductionmentioning

confidence: 99%

The performance of gradient alloy quantum dots in cell labeling

Soenen¹,

Manshian²,

Himmelreich³

et al. 2014

Biomaterials

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“…CdS 1Àx Se x quantum dots were synthesized via single injection of a R 3 PSÀR 3 PSe mixture to cadmium oleate at 250°C. X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV/Vis and PL optical spectroscopy reveal that relative R 3 PS and R 3 PSe reactivity dictates CdS 1Àx Se x dot chalcogen content and the extent of radial alloying (alloys vs core/shells). CdS, CdSe, and CdS 1Àx Se x quantum rods were synthesized by injection of a single R 3 PE (E = S or Se) precursor or a R 3 PSÀR 3 PSe mixture to cadmiumÀphosphonate at 320 or 250°C.…”

Section: Published Online 101021/nn301182hmentioning

confidence: 99%

Molecular Control of the Nanoscale: Effect of Phosphine–Chalcogenide Reactivity on CdS–CdSe Nanocrystal Composition and Morphology

et al. 2012

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We demonstrate molecular control of nanoscale composition, alloying, and morphology (aspect ratio) in CdS-CdSe nanocrystal dots and rods by modulating the chemical reactivity of phosphine-chalcogenide precursors. Specific molecular precursors studied were sulfides and selenides of triphenylphosphite (TPP), diphenylpropylphosphine (DPP), tributylphosphine (TBP), trioctylphosphine (TOP), and hexaethylphosphorustriamide (HPT). Computational (DFT), NMR ( 31 P and 77 Se), and high-temperature crossover studies unambiguously confirm a chemical bonding interaction between phosphorus and chalcogen atoms in all precursors. Phosphine-chalcogenide precursor reactivity increases in the order: TPPE < DPPE < TBPE < TOPE 1-x Se x quantum dots were synthesized via single injection of a R 3 PS-R 3 PSe mixture to cadmium oleate at 250 degree C. X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV/Vis and PL optical spectroscopy reveal that relative R 3 PS and R 3 PSe reactivity dictates CdS 1 -xSe x dot chalcogen content and the extent of radial alloying (alloys vs core/shells). CdS, CdSe, and CdS 1 -x Se x quantum rods were synthesized by injection of a single R 3 PE (E = S or Se) precursor or a R 3 PS-R 3 PSe mixture to cadmium-phosphonate at 320 or 250 degree C. XRD and TEM reveal that the length-to-diameter aspect ratio of CdS and CdSe nanorods is inversely proportional to R 3PE precursor reactivity. Purposely matching or mismatching R 3 PS-R 3 PSe precursor reactivity leads to CdS 1 -x Se x nanorods without or with axial composition gradients, respectively. We expect these observations will lead to scalable and highly predictable "bottom-up" programmed syntheses of finely heterostructured nanomaterials with well-defined architectures and properties that are tailored for precise applications. P reparative nanotechnology or "nanomanufacturing" is rapidly evolving toward fabrication of ever more complex materials with precise structure and properties. Tuning composition, relative configuration, and spatial arrangement of heterostructured nanomaterials can impact our ability to engineer and direct energy flows at the nanoscale. In the case of II 3 VI and IV 3 VI semiconductors, composition control has been demonstrated for homogeneously alloyed CdS 1Àx Se x , 1À4 CdS 1Àx Te x , 5 CdSe 1Àx Te x , 6 PbS x Se 1Àx , PbS x Te 1Àx , and PbSe x Te 1Àx 7 nanocrystals with size-and composition-tunable band gaps. 4,8,9 In some cases, a nonlinear relationship between composition and absorption/emission energies, called optical bowing, resulted in new properties not obtainable from the parent binary systems. 3 For example, CdS x Te 1Àx nanocrystals displayed small absorptionÀ emission spectral overlap, up to 150 nm Stokes shifts, and significantly red-shifted PL with respect to CdS and CdTe nanocrystals. 5 Controlling nanocrystal morphology is key to controlling nanocrystal properties. 10À14 A common technique to produce nanorods, for example, is to perform slow and/or subsequent reactant injections. 15À17 In i...

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“…Moreover, core/shell hetero-NCs with a gradient alloy heterointerface have been shown to possess unique properties, such as reduced Auger recombination rates and lower threshold for amplified spontaneous emission [84]. Alloy QDs and graded interface core/shell hetero-NCs can also be directly synthesized and have attracted increasing interest in the last few years, leading to the investigation of several II-VI and IV-VI compositions [viz., Cd(Te,Se), Cd(S,Se), Pb(S,Se), (Cd,Zn)Se, (Cd,Zn)S, (Cd,Zn)(S,Se)] [80][81][82][83][84][85][86][87][88][89].…”

Section: Composition Effects: Tailoring the Property Gamutmentioning

confidence: 99%

Excited-State Dynamics in Colloidal Semiconductor Nanocrystals

Rabouw

Donegá

2016

Topics in Current Chemistry Collections

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Colloidal semiconductor nanocrystals have attracted continuous worldwide interest over the last three decades owing to their remarkable and unique sizeand shape-, dependent properties. The colloidal nature of these nanomaterials allows one to take full advantage of nanoscale effects to tailor their optoelectronic and physical-chemical properties, yielding materials that combine size-, shape-, and composition-dependent properties with easy surface manipulation and solution processing. These features have turned the study of colloidal semiconductor nanocrystals into a dynamic and multidisciplinary research field, with fascinating fundamental challenges and dazzling application prospects. This review focuses on the excited-state dynamics in these intriguing nanomaterials, covering a range of different relaxation mechanisms that span over 15 orders of magnitude, from a few femtoseconds to a few seconds after photoexcitation. In addition to reviewing the state of the art and highlighting the essential concepts in the field, we also discuss

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Alloyed Semiconductor Quantum Dots: Tuning the Optical Properties without Changing the Particle Size

Cited by 901 publications

References 59 publications

The performance of gradient alloy quantum dots in cell labeling

The performance of gradient alloy quantum dots in cell labeling

Molecular Control of the Nanoscale: Effect of Phosphine–Chalcogenide Reactivity on CdS–CdSe Nanocrystal Composition and Morphology

Excited-State Dynamics in Colloidal Semiconductor Nanocrystals

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