Precursor reaction kinetics control compositional grading and size of CdSe<sub>1−x</sub>S<sub>x</sub> nanocrystal heterostructures

Hamachi, Leslie S.; Yang, Haoran; Plante, Ilan Jen‐La; Saenz, Natalie; Qian, Kevin; Campos, Michael P.; Cleveland, Gregory T.; Rreza, Iva; Oza, Aisha; Walravens, Willem; Chan, Emory M.; Hens, Zeger; Crowther, Andrew C.; Owen, Jonathan S.

doi:10.1039/c9sc00989b

Cited by 24 publications

(64 citation statements)

References 71 publications

(119 reference statements)

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“…Our results can be explained using the nucleation mass balance model formalized by Sugimoto and described in previous studies on PbS, PbSe, CdS, CdSe, AgCl, and AgBr. − ,,− This model explains how the nucleation and the growth processes compete with one another for supersaturated solutes (Scheme ). The model defines nucleation as the formation of “stable nuclei”, that is, crystals that do not redissolve but grow to their final size.…”

Section: Discussionmentioning

confidence: 83%

Continuous Nucleation and Size Dependent Growth Kinetics of Indium Phosphide Nanocrystals

et al. 2020

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Aminophosphines derived from N,N′-disubstituted ethylenediamines (R−N(H)CH 2 CH 2 N(H)−R; R = ortho-tolyl, phenyl, benzyl, iso-propyl, and n-octyl) were used to adjust the kinetics of InP nanocrystal formation by more than 1 order of magnitude. Ultraviolet−visible absorption and 31 P nuclear magnetic resonance measurements demonstrate that the rate of nanocrystal formation is limited by the precursor reactivity. At low temperature (180°C), crystal nucleation is concurrent with growth throughout the reaction, rather than occurring in a burst at early times. The low temperature produces a narrow range of small sizes (d = 4.2−4.9 nm) regardless of the precursor used. Higher temperatures (up to 270°C) promote growth to larger sizes (d ≤ 7.8 nm), shorten the nucleation period, and create conditions where the final size is controlled by the precursor conversion reactivity. The temperature dependence is proposed to arise from growth kinetics that slow as the nanocrystal size increases, a novel surface attachment limited size distribution-focusing mechanism. Such a mechanism supports a narrow size distribution without separating the nucleation and growth phases.

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Section: Discussionmentioning

confidence: 83%

Continuous Nucleation and Size Dependent Growth Kinetics of Indium Phosphide Nanocrystals

et al. 2020

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Section: Discussionmentioning

confidence: 99%

“…For old systems, such as CdSe/CdS QDs, their synthesis has been extensively optimized to yield QDs having almost unity QY and high crystallinity 5 , 56 . Common approaches include varying ligands 56 , a temperature profile during reaction 5 , and precursors 35 , but the established strategies are only applicable to the QDs of a specific material or size range. Here we identify the key parameters impacting the quality of nanocrystals, including their crystallinity, morphology, density of defects, and core-shell interface structure, and introduce a design principle for precursors that enables systematic optimization of the growth condition.…”

Section: Discussionmentioning

confidence: 99%

“…For instance, metal precursors often lack precursors having intermediate reactivity (e.g., diethylzinc vs. zinc(carboxylate) 2 ). Recently, researchers have made progress toward a systematic modulation of precursor conversion rate by synthesizing a library of molecules containing different organic substituents 19,[35][36][37] . However, this approach requires synthesis of a large number of precursor variants, which is labor intensive and time consuming; furthermore, we learned that the reactivity range covered by the recently developed sulfur precursor library is not optimal for QD growth (see Supplementary Results).…”

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Controllable modulation of precursor reactivity using chemical additives for systematic synthesis of high-quality quantum dots

et al. 2020

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The optical and electronic performance of quantum dots (QDs) are affected by their size distribution and structural quality. Although the synthetic strategies for size control are well established and widely applicable to various QD systems, the structural characteristics of QDs, such as morphology and crystallinity, are tuned mostly by trial and error in a material-specific manner. Here, we show that reaction temperature and precursor reactivity, the two parameters governing the surface-reaction kinetics during growth, govern the structural quality of QDs. For conventional precursors, their reactivity is determined by their chemical structure. Therefore, a variation of precursor reactivity requires the synthesis of different precursor molecules. As a result, existing precursor selections often have significant gaps in reactivity or require synthesis of precursor libraries comprising a large number of variants. We designed a sulfur precursor employing a boron-sulfur bond, which enables controllable modulation of their reactivity using commercially available Lewis bases. This precursor chemistry allows systematic optimization of the reaction temperature and precursor reactivity using a single precursor and grows high-quality QDs from cores of various sizes and materials. This work provides critical insights into the nanoparticle growth process and precursor designs, enabling the systematic preparation of high-quality QD of any sizes and materials.

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“…The ability to visualize the evolution of nanoscale reactions without labor-intensive fabrication will facilitate the direct testing of mechanistic theories, accelerating the development of new materials and helping to elucidate the complex reaction networks that produce them. [106][107][108]…”

Section: Discussionmentioning

confidence: 99%

Hybrid nanocapsules for in situ TEM imaging of gas evolution reactions in confined liquids

et al. 2020

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Precursor reaction kinetics control compositional grading and size of CdSe_1−xS_x nanocrystal heterostructures

Abstract: By varying precursor structure, core/shell and alloyed nanocrystal synthesis are performed in a single synthetic step.

Cited by 24 publications

References 71 publications

Continuous Nucleation and Size Dependent Growth Kinetics of Indium Phosphide Nanocrystals

Continuous Nucleation and Size Dependent Growth Kinetics of Indium Phosphide Nanocrystals

Controllable modulation of precursor reactivity using chemical additives for systematic synthesis of high-quality quantum dots

Hybrid nanocapsules for in situ TEM imaging of gas evolution reactions in confined liquids

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Precursor reaction kinetics control compositional grading and size of CdSe1−xSx nanocrystal heterostructures

Abstract: By varying precursor structure, core/shell and alloyed nanocrystal synthesis are performed in a single synthetic step.

Cited by 24 publications

References 71 publications

Continuous Nucleation and Size Dependent Growth Kinetics of Indium Phosphide Nanocrystals

Continuous Nucleation and Size Dependent Growth Kinetics of Indium Phosphide Nanocrystals

Controllable modulation of precursor reactivity using chemical additives for systematic synthesis of high-quality quantum dots

Hybrid nanocapsules for in situ TEM imaging of gas evolution reactions in confined liquids

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Precursor reaction kinetics control compositional grading and size of CdSe_1−xS_x nanocrystal heterostructures