Addition of Zn during the phosphine-based synthesis of indium phospide quantum dots: doping and surface passivation

Mordvinova, Natalia E.; Vinokurov, A. A.; Lebedev, Oleg I.; Dorofeev, S. G.

doi:10.3762/bjnano.6.127

Cited by 13 publications

(8 citation statements)

References 24 publications

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“…The higher growth rate at high temperatures contradicts previous reports that zinc additives passivate the surface of particles counteracting the growth of QDs or ripening. 33,51 Moreover, the slow nucleation and growth into uniform size in the case of In(Zn)P QDs demand systematic and molecular investigation of the growth.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…With increasing zinc to indium precursor ratio, the PL peak shifts to higher energy in both cases (Figure 4A), which is attributed to the surface passivation and etching effects of zinc carboxylate that counteract the growth of QDs. 33,51 The fwhm of QDs from the In−P complex remains large with an increasing ratio of zinc to indium precursors up to 350 meV, whereas the fwhm of QDs from the Zn−P complex gradually decreases to 240 meV (Figure 4B). This indicates that the amount of zinc carboxylate does not compensate for the high reactivity of the In−P complex that results in polydisperse QDs.…”

Section: T H Imentioning

confidence: 99%

“…31 Alloying and doping of InP QDs with other cations, e.g., Zn 2+ , have offered a somewhat different angle of attack with regard to size uniformity and thus the emission color purity. 32,33 These approaches result in both enhanced color purity and increased photoluminescence (PL) quantum yield (QY) in comparison to those of bare InP QDs synthesized in nearly identical reaction conditions. 32,34,35 In this sense, the addition of zinc sources in the synthesis of InP QDs has been recognized by several accounts to elevate the color purity of the QDs.…”

Section: ■ Introductionmentioning

confidence: 99%

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Zinc–Phosphorus Complex Working as an Atomic Valve for Colloidal Growth of Monodisperse Indium Phosphide Quantum Dots

Koh¹,

Eom²,

Kim³

et al. 2017

Chem. Mater.

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Growth of monodisperse indium phosphide (InP) quantum dots (QDs) represents a pressing demand in display applications, as size uniformity is related to color purity in display products. Here, we report the colloidal synthesis of InP QDs in the presence of Zn precursors in which size uniformity is markedly enhanced as compared to the case of InP QDs synthesized without Zn precursors. Nuclear magnetic resonance spectroscopy, X-ray photoelectron spectroscopy, and mass spectrometry analyses on aliquots taken during the synthesis allow us to monitor the appearance of metal− phosphorus complex intermediates in the growth of InP QDs. In the presence of zinc carboxylate, intermediate species containing Zn−P bonding appears. The Zn−P intermediate complex with P(SiMe 3 ) 3 exhibits lower reactivity than that of the In−P complex, which is corroborated by our prediction based on density functional theory and electrostatic potential charge analysis. The formation of a stable Zn−P intermediate complex results in lower reactivity, which enables slow growth of QDs and lowers the extreme reactivity of P(SiMe 3 ) 3 , hence monodisperse QDs. Insights from experimental and theoretical studies advance mechanistic understanding and control of nucleation and growth of InP QDs, which are key to the preparation of monodisperse InP-based QDs in meeting the demand of the display market.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: T H Imentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

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Zinc–Phosphorus Complex Working as an Atomic Valve for Colloidal Growth of Monodisperse Indium Phosphide Quantum Dots

Koh¹,

Eom²,

Kim³

et al. 2017

Chem. Mater.

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“…InP/ZnS and InPZnS/ZnS core/shell and alloy/shell quantum dots (QDs) have been recently proposed as a viable, cadmium-free alternative to cadmium-containing QDs, such as CdS/ZnS, CdSe/ZnS, and CdTe/CdSe/ZnS QDs. − Historically, a major challenge for InP QD synthesis lies in the need to replace highly reactive, pyrophoric phosphorus precursors such as tris(trimethylsilyl)phosphine [P(TMS) 3 ] with safer and more stable precursors. In addition to posing significant safety concerns, the use of highly reactive molecular precursors leads to heterogeneous crystal growth, broad InP QD size distribution, and broad emission peaks .…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Degradation of Cadmium-Free InP and InPZn/ZnS Quantum Dots in Solution

et al. 2018

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This study advances the chemical research community toward the goal of replacing toxic cadmium-containing quantum dots (QDs) with environmentally benign InP QDs. The InP QD synthesis uniquely combines the previously reported use of InP magic-sized clusters (MSCs) as a single-source precursor for indium and phosphorus to form InP QDs, with zinc incorporation and subsequent ZnS shelling, to form InPZn/ZnS QDs with luminescence properties comparable to those of commonly used cadmium-containing luminescent QDs. The resulting InPZn/ZnS QDs have an emission quantum yield of about 50% across a broad range of emission peak wavelengths and emission peaks averaging 50 nm fwhm. The emission peak wavelength can be easily tuned by varying the Zn/In ratio in the reaction mixture. The strategy of using zinc stearate to tune the emission properties is advantageous as it does not lead to a loss of emission quantum yield or emission peak broadening. Although the initial optical properties of InP and InPZn/ZnS QDs are promising, thermal stability measurements of InPZn QDs show significant degradation in the absence of a shell compared to the CdSe QDs particularly at increased temperature in the presence of oxygen, which is indicative of thermal oxidation. There is no significant difference in the degradation rate of InP QDs made from molecular precursors and from MSCs. Additionally, the emission intensity and quantum yield of InPZn/ZnS QDs when purified and diluted in organic solvents under ambient conditions decrease significantly compared to those of CdSe/ ZnS QDs. This indicates instability of the ZnS shell when prepared by common literature methods. This must be improved to realize high-quality, robust Cd-free QDs with the capability of replacing CdSe QDs in QD technologies.

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“…Although the addition of Zn to the synthesis of InP nanocrystals has become common practice in the last years, − ,− very little has been reported on the actual role of the Zn. The few reports on this topic have focused on the effect on the optical properties, but structural aspects were not investigated. ,, Here, instead we carry out a detailed investigation on the location of Zn 2+ in the InP QD lattice. Such compositional tunability is then exploited to match the lattice parameter of the In x Zn y P cores to that of a range of shell materials (GaP, ZnSe and ZnS) which otherwise would not be compatible with InP.…”

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confidence: 99%

Tuning the Lattice Parameter of In_xZn_yP for Highly Luminescent Lattice-Matched Core/Shell Quantum Dots

et al. 2016

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Colloidal quantum dots (QDs) show great promises as LED phosphors due to their tuneable narrow-band emission and ability to produce high-quality white light.Currently, the most suitable QDs for lighting applications are based on cadmium, which presents a toxicity problem for consumer applications. The most promising cadmiumfree candidate QDs are based on InP, but their quality lags much behind that of cadmium based QDs. This is not only because the synthesis of InP QDs is more challenging than that of Cd-based QDs, but also because the large lattice parameter of InP makes it difficult to grow an epitaxial, defect free shell on top of such material. Here we propose an original approach to overcome this problem by alloying InP nanocrystals with Zn 2+ ions, which enables the synthesis of In x Zn y P alloy QDs having lattice constant that can be tuned from 5.93 Å (pure InP QDs) down to 5.39 Å by simply varying the concentration of the Zn precursor. This lattice engineering allows for subsequent strainfree, epitaxial growth of a ZnSe z S 1-z shell with lattice parameters matching that of the core. We demonstrate, for a wide range of core and shell compositions (i.e. varying x, y and z), that the photoluminescence quantum yield is maximal (up to 60%) when lattice mismatch is minimal.3

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Addition of Zn during the phosphine-based synthesis of indium phospide quantum dots: doping and surface passivation

Cited by 13 publications

References 24 publications

Zinc–Phosphorus Complex Working as an Atomic Valve for Colloidal Growth of Monodisperse Indium Phosphide Quantum Dots

Zinc–Phosphorus Complex Working as an Atomic Valve for Colloidal Growth of Monodisperse Indium Phosphide Quantum Dots

Synthesis and Degradation of Cadmium-Free InP and InPZn/ZnS Quantum Dots in Solution

Tuning the Lattice Parameter of In_xZn_yP for Highly Luminescent Lattice-Matched Core/Shell Quantum Dots

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Addition of Zn during the phosphine-based synthesis of indium phospide quantum dots: doping and surface passivation

Cited by 13 publications

References 24 publications

Zinc–Phosphorus Complex Working as an Atomic Valve for Colloidal Growth of Monodisperse Indium Phosphide Quantum Dots

Zinc–Phosphorus Complex Working as an Atomic Valve for Colloidal Growth of Monodisperse Indium Phosphide Quantum Dots

Synthesis and Degradation of Cadmium-Free InP and InPZn/ZnS Quantum Dots in Solution

Tuning the Lattice Parameter of InxZnyP for Highly Luminescent Lattice-Matched Core/Shell Quantum Dots

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Tuning the Lattice Parameter of In_xZn_yP for Highly Luminescent Lattice-Matched Core/Shell Quantum Dots