Heat-induced transformation of CdSe–CdS–ZnS core–multishell quantum dots by Zn diffusion into inner layers

Yalcin, Anil O.; Goris, Bart; Dijk-Moes, Relinde J. A. van; Fan, Zhiqin; Erdamar, A. K.; Tichelaar, F.D.; Vlugt, Thijs J. H.; Tendeloo, Gustaaf Van; Bals, Sara; Vanmaekelbergh, Daniël; Zandbergen, H.W.; Huis, Marijn A. van

doi:10.1039/c4cc08647c

Cited by 19 publications

(36 citation statements)

References 34 publications

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“…Cd sublimation of heterogeneous NCs was previously observed in colloidal CdSe, CdSe/Cu 3 P/CdSe NCs, NCs and CdSe/PbSe NCs68910. The sublimation temperatures are as low as 450 K (ref.…”

Section: Resultsmentioning

confidence: 82%

Electrically driven cation exchange for in situ fabrication of individual nanostructures

et al. 2017

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Cation exchange (CE) has been recognized as a particularly powerful tool for the synthesis of heterogeneous nanocrystals. At present, CE can be divided into two categories, namely ion solvation-driven CE reaction and thermally activated CE reaction. Here we report an electrically driven CE reaction to prepare individual nanostructures inside a transmission electron microscope. During the process, Cd is eliminated due to Ohmic heating, whereas Cu+ migrates into the crystal driven by the electrical field force. Contrast experiments reveal that the feasibility of electrically driven CE is determined by the structural similarity of the sulfur sublattices between the initial and final phases, and the standard electrode potentials of the active electrodes. Our experimental results demonstrate a strategy for the selective growth of individual nanocrystals and provide crucial insights into understanding of the microscopic pathways leading to the formation of heterogeneous structures.

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“…Cd sublimation of heterogeneous NCs was previously observed in colloidal CdSe, CdSe/Cu 3 P/CdSe NCs, NCs and CdSe/PbSe NCs68910. The sublimation temperatures are as low as 450 K (ref.…”

Section: Resultsmentioning

confidence: 82%

Electrically driven cation exchange for in situ fabrication of individual nanostructures

et al. 2017

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“…It has been also shown experimentally that PbS/CdS HNCs obtained by CE have a sharp PbS/CdS boundary 17 19 . Unlike systems containing materials with the same crystal structure, which easily form mixed phases or solid solutions (for example, the CdSe/ZnSe 10 and CdSe/CdS/ZnS 31 systems), PbS and CdS in HNCs undergo a phase separation even at relatively high temperatures 24 26 .…”

Section: Resultsmentioning

confidence: 99%

Atomistic understanding of cation exchange in PbS nanocrystals using simulations with pseudoligands

et al. 2016

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Cation exchange is a powerful tool for the synthesis of nanostructures such as core–shell nanocrystals, however, the underlying mechanism is poorly understood. Interactions of cations with ligands and solvent molecules are systematically ignored in simulations. Here, we introduce the concept of pseudoligands to incorporate cation-ligand-solvent interactions in molecular dynamics. This leads to excellent agreement with experimental data on cation exchange of PbS nanocrystals, whereby Pb ions are partially replaced by Cd ions from solution. The temperature and the ligand-type control the exchange rate and equilibrium composition of cations in the nanocrystal. Our simulations reveal that Pb ions are kicked out by exchanged Cd interstitials and migrate through interstitial sites, aided by local relaxations at core–shell interfaces and point defects. We also predict that high-pressure conditions facilitate strongly enhanced cation exchange reactions at elevated temperatures. Our approach is easily extendable to other semiconductor compounds and to other families of nanocrystals.

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“…2(a,c,e,g) , and their PL emission peaks are 675, 596, 595, and 580 nm, respectively. The PL peaks of (Zn)CuInS alloyed QDs exhibit a blue shift of about 35 nm compared with the original CuInS QDs ( Supplementary Table S1 and S2 ), which was due to surface etching of CuInS QDs 29 32 33 34 and the indium content variation in the (Zn)CuInS alloyed QDs 35 36 37 . The PL QYs of these alloyed QDs samples were about 3.8%, 16.8%, 24.9%, and 36.3%, respectively ( Supplementary Fig.…”

Section: Resultsmentioning

confidence: 99%

Non-blinking (Zn)CuInS/ZnS Quantum Dots Prepared by In Situ Interfacial Alloying Approach

Zhang

Dong

Liang

et al. 2015

Sci Rep

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Semiconductor quantum dots (QDs) are very important optical nanomaterials with a wide range of potential applications. However, blinking behavior of single QD is an intrinsic drawback for some biological and photoelectric applications based on single-particle emission. Herein we present a rational strategy for fabrication of non-blinking (Zn)CuInS/ZnS QDs in organic phase through in situ interfacial alloying approach. This new strategy includes three steps: synthesis of CuInS QDs, eliminating the interior traps of QDs by forming graded (Zn)CuInS alloyed QDs, modifying the surface traps of QDs by introducing ZnS shells onto (Zn)CuInS QDs using alkylthiols as sulfur source and surface ligands. The suppressed blinking mechanism was mainly attributed to modifying QDs traps from interior to exterior via a step-by-step modification. Non-blinking QDs show high quantum yield, symmetric emission spectra and excellent crystallinity, and will enable applications from biology to optoelectronics that were previously hindered by blinking behavior of traditional QDs.

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Heat-induced transformation of CdSe–CdS–ZnS core–multishell quantum dots by Zn diffusion into inner layers

Cited by 19 publications

References 34 publications

Electrically driven cation exchange for in situ fabrication of individual nanostructures

Electrically driven cation exchange for in situ fabrication of individual nanostructures

Atomistic understanding of cation exchange in PbS nanocrystals using simulations with pseudoligands

Non-blinking (Zn)CuInS/ZnS Quantum Dots Prepared by In Situ Interfacial Alloying Approach

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