Synthesis of Soluble and Processable Rod-, Arrow-, Teardrop-, and Tetrapod-Shaped CdSe Nanocrystals

Manna, Liberato; Scher, and Erik C.; Alivisatos, A. Paul

doi:10.1021/ja003055+

Cited by 1,770 publications

(1,695 citation statements)

References 34 publications

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“…Experimentally, we observe that differently substituted dichalcogenides lead to completely different nanocrystal morphologies, some lead to dots, others to rods or tetrapods. The selectivity for such anisotropic structures is obviously affected by reaction parameters such as reaction time 17 and temperature, 18,19 precursor concentration, 20 medium acidity, 21 ligand type (amines, 22À24 halides, 52 phosphonic acids 25,26 ) and chain length. 27,28 Commonly used methods to obtain IIÀVI and IVÀVI rods and tetrapods include seeded growth, 29À32 continuous precursor injection, 33,34 and noninjection routes.…”

Section: Ialkyl Dichalcogenides (Ràeàeàr;mentioning

confidence: 99%

Shape-Programmed Nanofabrication: Understanding the Reactivity of Dichalcogenide Precursors

et al. 2013

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Dialkyl and diaryl dichalcogenides are highly versatile and modular precursors for the synthesis of colloidal chalcogenide nanocrystals. We have used a series of commercially available dichalcogenide precursors to unveil the molecular basis for the outcome of nanocrystal preparations, more specifically, how precursor molecular structure and reactivity affect the final shape and size of II-VI semiconductor nanocrystals. Dichalcogenide precursors used were diallyl, dibenzyl, di-tert-butyl, diisopropyl, diethyl, dimethyl, and diphenyl disulfides and diethyl, dimethyl, and diphenyl diselenides. We find that the presence of two distinctively reactive C-E and E-E bonds makes the chemistry of these precursors much richer and interesting than that of other conventional precursors such as the more common phosphine chalcogenides. Computational studies (DFT) reveal that the dissociation energy of carbon-chalcogen (C-E) bonds in dichalcogenide precursors (R-E-E-R, E = S or Se) increases in the order (R): diallyl < dibenzyl < di-tert-butyl < diisopropyl < diethyl < dimethyl < diphenyl. The dissociation energy of chalcogen-chalcogen (E-E) bonds remains relatively constant across the series. The only exceptions are diphenyl dichalcogenides, which have a much lower E-E bond dissociation energy. An increase in C-E bond dissociation energy results in a decrease in R-E-E-R precursor reactivity, leading to progressively slower nucleation and higher selectivity for anisotropic growth, all the way from dots to pods to tetrapods. Under identical experimental conditions, we obtain CdS and CdSe nanocrystals with spherical, elongated, or tetrapodal morphology by simply varying the identity and reactivity of the dichalcogenide precursor. Interestingly, we find that precursors with strong C-E and weak E-E bond dissociation energies such as Ph-S-S-Ph serve as a ready source of thiol radicals that appear to stabilize small CdE nuclei, facilitating anisotropic growth. These CdS and CdSe nanocrystals have been characterized using structural and spectroscopic methods. An intimate understanding of how molecular structure affects the chemical reactivity of molecular precursors enables highly predictable and reproducible synthesis of colloidal nanocrystals with specific sizes, shapes, and optoelectronic properties for customized applications. D ialkyl dichalcogenides (RÀEÀEÀR;where R = alkyl or aryl, E = S, Se, or Te) recently re-emerged as highly versatile molecular precursors for the solution-phase synthesis of colloidal nanocrystals. Intriguingly, these dichalcogenides enable the isolation of metastable nanocrystalline phases with unusual composition and morphology. tBuÀEÀEÀtBu (E = S or Se) precursors allow the isolation of CuInE 2 and Cu 2 SnE 3 nanocrystals with metastable wurtzite phases. 1,2 A change in reaction solvent from oleylamine to squalene leads to CuInE 2 nanocrystals with the more stable chalcopyrite phase. 2,3 tBuÀSÀSÀtBu serves as precursor to In 2 S 3 nanorods 4 and Cu 2Àx S nanocrystals with a wide range of morpholog...

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Section: Ialkyl Dichalcogenides (Ràeàeàr;mentioning

confidence: 99%

Shape-Programmed Nanofabrication: Understanding the Reactivity of Dichalcogenide Precursors

et al. 2013

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“…A wide variety of anisotropic particles with diverse anisotropy in size, shape [1][2][3][4][5][6][7] and chemical functionality [8][9][10][11][12][13][14][15][16][17][18][19][20] has been explored. Within such a large diversity of anisotropic particles, significant attention has been given lately to the study of surface-anisotropic particles, that is, particles exhibiting multiple surface functionalities, while often having an isotropic polymer core.…”

Section: Introductionmentioning

confidence: 99%

Fabrication, Assembly, and Application of Patchy Particles

Pawar

Kretzschmar

2010

Macromol. Rapid Commun.

447

411

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The site‐specific engineering of colloidal surfaces has provided a powerful approach to pushing the boundaries of today's materials research. The resulting surface‐anisotropic and patchy particles have become the center of vital research areas, ranging from the need for large‐scale fabrication techniques to exploring new applications of these materials. This Review summarizes patchy particle fabrication techniques, including but not limited to particle and nanosphere lithography and glancing‐angle deposition. The variety of existing patchy particle fabrication techniques is revealed and the need for a scalable approach to high‐volume patchy particle production is identified. Ongoing modeling efforts describing patchy particle interactions and properties are reviewed as potential predictive tools. Research endeavors that deal with the directed assembly of patchy particles in electric and magnetic fields, as well as with supraparticular assembly through chemical interactions, are discussed. The Review is concluded with a note on the future application of patchy particles as phoretic motors.magnified image

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“…For this reason this approach has been extensively adopted for the preparation of colloidal nanoparticles which have provided model systems for the study of crystal growth and of factors affecting phase and shape stability at the nanometer scale. [8][9][10][11][12][13] Many recent studies point out the effect of the growth conditions on the outcome of the synthesis: for example by varying the growth temperature one may achieve size and/or shape control by tuning the growth rate or phase control by making more favorable the growth of one polymorph. On the other hand, the nucleation is more difficult to control as it depends exponentially on concentration and temperature.…”

Section: Introductionmentioning

confidence: 99%

The Concept of Delayed Nucleation in Nanocrystal Growth Demonstrated for the Case of Iron Oxide Nanodisks

et al. 2006

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RECEIVED DATE (to be automatically inserted after your manuscript is accepted if required according to the journal that you are submitting your paper to) TITLE RUNNING HEAD. Monodisperse Iron Oxide Nanodisks by Delayed Nucleation 2 ABSTRACT A comprehensive study of iron oxide nanocrystal growth through non-hydrolitic, surfactantmediated thermal reaction of iron pentacarbonyl and an oxidizer has been conducted, which includes size control, anisotropic shape evolution, and crystallographic phase transition of monodisperse iron oxide colloidal nanocrystals. The reaction was monitored by in situ UV-Vis spectroscopy taking advantage of the color change accompanying the iron oxide colloid formation allowing measurement of the induction time for nucleation. Features of the synthesis such as the size control and reproducibility are related to the occurrence of the observed delayed nucleation process. As a separate source of iron and oxygen is adopted, phase control could also be achieved by sequential injections of oxidizer.3

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Synthesis of Soluble and Processable Rod-, Arrow-, Teardrop-, and Tetrapod-Shaped CdSe Nanocrystals

Cited by 1,770 publications

References 34 publications

Shape-Programmed Nanofabrication: Understanding the Reactivity of Dichalcogenide Precursors

Shape-Programmed Nanofabrication: Understanding the Reactivity of Dichalcogenide Precursors

Fabrication, Assembly, and Application of Patchy Particles

The Concept of Delayed Nucleation in Nanocrystal Growth Demonstrated for the Case of Iron Oxide Nanodisks

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