Shape and Phase Control of Colloidal ZnSe Nanocrystals

Cozzoli, P. Davide; Manna, Liberato; Curri, M. Lucia; Kudera, Stefan; Giannini, Cinzia; Striccoli, Marinella; Agostiano, Angela

doi:10.1021/cm047874v

Cited by 230 publications

(256 citation statements)

References 105 publications

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“…19 Aspect ratio is sensitive to phosphonic acid alkyl chain length; the shorter the chain, the more elongated and branched are the nanorods. 18,20 Aspect ratio control has been studied for ZnS, ZnSe,16,21 ABSTRACT We demonstrate molecular control of nanoscale composition, alloying, and morphology …”

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confidence: 98%

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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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 propose that the formation of the EuSe NCs requires the amine to act as a reducing agent. [25][26][27][28][29][30][31][32] Our approach is simple and effective, using EuCl 3 (H 2 O) 6 and elemental selenium as Eu and Se sources, respectively. The overall synthetic procedure for EuSe NCs is depicted in Scheme 1.…”

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confidence: 99%

“…There is a limited body of literature on the preparation of colloidal nanocrystals (NCs) by a reduction route, [25][26][27][28][29] even when amines were used. [30][31][32] It was reported that OLA could reduce Ag + and Au 3+ ions to form Ag and Au nanoparticles, respectively. [33][34][35] Note that for our EuSe NCs prepared in the absence of OLA, we observed the characteristic luminescence of Eu 3+ peaking at 592 nm and 615 nm (Supporting Information Figure S5a).…”

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A Simple Reducing Approach Using Amine To Give Dual Functional EuSe Nanocrystals and Morphological Tuning

Wang

Zhang

et al. 2011

Angew Chem Int Ed

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“…6 More recently, Cozzoli et al studied the shape and phase control of colloidal ZnSe NPs, where the as-prepared NPs exhibited distinguishable, shape-dependent optical properties in the UVblue region. 7 They observed that a red-shift of the bandgap in longer nanorods, or in general branched nanostructures with long rod sections, was generally accompanied by a significant decrease in the photoluminescence (PL) QY, which could be much lower than 1% for the branched structures.…”

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Synthesis and characterization of core/shell Fe3O4/ZnSe fluorescent magnetic nanoparticles

Vargas

McBride

Plumley

et al. 2011

Journal of Applied Physics

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We report on the successful preparation and characterization of fluorescent magnetic core/shell Fe 3 O 4 /ZnSe nanoparticles (NPs) with a spherical shape by organometallic synthesis. The 7 nm core/3 nm shell NPs show good magnetic and photoluminescence (PL) responses. The observed PL emission/excitation spectra are shifted to shorter wavelengths, compared to a reference ZnSe NP sample. A dramatic reduction of PL quantum yield is also observed. The temperature dependence of the magnetization for the core/shell NPs shows the characteristic features of two coexisting and interacting magnetic (Fe 3 O 4 ) and nonmagnetic (ZnSe) phases. Compared to a reference Fe 3 O 4 NP sample, the room-temperature Néel relaxation time in core/shell NPs is three times longer.

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Shape and Phase Control of Colloidal ZnSe Nanocrystals

Cited by 230 publications

References 105 publications

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

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

A Simple Reducing Approach Using Amine To Give Dual Functional EuSe Nanocrystals and Morphological Tuning

Synthesis and characterization of core/shell Fe3O4/ZnSe fluorescent magnetic nanoparticles

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