An efficient and surface-benign purification scheme for colloidal nanocrystals based on quantitative assessment

Yang, Yingzhen; Li, Jiongzhao; Lin, Lie; Peng, Xiaogang

doi:10.1007/s12274-015-0835-6

Cited by 37 publications

(55 citation statements)

References 46 publications

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“…5-7 and the synthesis reaction was run under cadmium-rich conditions. It is notoriously difficult to remove cadmium stearate completely from QD preparations synthesized in this way, 32 and this is particularly true when the purification is done by precipitation by the addition of methanol, as was done in refs. 5-7.…”

Section: Discussionmentioning

confidence: 99%

“…Ref. 32 shows that the stearates tend to precipitate with the CdSe QDs and that five cycles of this purification removes less than 20% of the excess cadmium stearate. We therefore suggest that under the conditions of those experiments a small amount of unreacted cadmium stearate was still present when the DTC ligand was added, allowing the deposition of a small amount of additional cadmium as well as sulfur onto the CdSe surface.…”

Section: Discussionmentioning

confidence: 99%

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Resonance Raman Investigation of the Interaction between Aromatic Dithiocarbamate Ligands and CdSe Quantum Dots

et al. 2017

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Ligand exchange with phenyl dithiocarbamates is known to significantly red-shift the lowest excitonic transition of CdSe quantum dots. Here we show that the resonance Raman spectra of CdSe quantum dots treated with p-methoxyphenyldithiocarbamate are nearly identical to those of CdSe quantum dots to which thin CdS shells have been added by standard synthetic methods.We conclude that the dithiocarbamate ligands decompose and react with Cd 2+ not fully removed following the synthesis to form CdS on the surface of the quantum dots. This red-shifts the absorption spectrum primarily by delocalizing the electron into the CdS shell. These results are consistent with the common use of aliphatic dithiocarbamates as single-source precursors for adding ZnS or CdS shells to CdSe quantum dots, and with the recent demonstration through NMR that phenyldithiocarbamate ligands decompose during nanocrystal ligand exchange.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Resonance Raman Investigation of the Interaction between Aromatic Dithiocarbamate Ligands and CdSe Quantum Dots

et al. 2017

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“…34,37 As shown in Figure S12 (Supporting Information), purification using the precipitation procedure with acetonitrile did not vary the PL properties of CdSe/5CdS core/shell QDs obtained from the phosphine-free approach. 53 In comparison, the same QDs treated with tributylphosphine-also with ~100% PL QY-lost their PL brightness significantly upon the same precipitation procedure. Overall, the stability and durability at a single-dot level of the cadmium carboxylate-treated…”

Section: Verification Of H 2 S As Detrimental Hole Traps By Ligand Exmentioning

confidence: 97%

To Battle Surface Traps on CdSe/CdS Core/Shell Nanocrystals: Shell Isolation versus Surface Treatment

2016

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Electronic traps at the inorganic-organic interface of colloidal quantum dots (QDs) are detrimental to their luminescent properties. Several types of interface traps were identified for single-crystalline CdSe/CdS core/shell QDs, which were all found to be extrinsic to either the core/shell structure or their optical performance. The electron traps-presumably excess or unpassivated Cd surface sites-are shallow ones and could be readily isolated from the electron wave function of the excitons with more than ∼2 monolayers of CdS shell. There were two identifiable deep hole traps within the bandgap of the QDs, i.e., the surface adsorbed H2S and unpassivated surface S sites. The surface adsorbed H2S could be removed by either degassing processes or photochemical decomposition of H2S without damaging the QDs. The unpassivated surface S sites could be removed by surface treatment with cadmium carboxylates. Understanding of the surface traps enabled establishment of new phosphine-free synthetic schemes for either single-precursor or successive-ion-layer-adsorption-and-reaction approach, which yielded CdSe/CdS core/shell QDs with near-unity photoluminescence quantum yield and monoexponential photoluminescence decay dynamics with 2-10 monolayers of CdS shell.

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“…[27,28] For example, the development of complex solar-cell architectures will require porous perovskite films infiltrated with at ransparent charge transport-Nanoparticles of hybrid organic-inorganic perovskites have attracted ag reat deal of attention due to their variety of optoelectronic properties, their low cost, and their easier integration into devices with complex geometry,c ompared with microcrystalline, thin-film, or bulk metal halides. [29] Compared with the preparation of other types of nanoparticles, such as traditional inorganic semiconductor quantum dots, metal NPs, or even inorganic perovskites, [30][31][32][33][34] the synthesis of HyP-NPs is not as well developed. Starting from ab ulk CH 3 NH 3 PbBr 3 crystal,o ur PLIL procedure does not involve the use of high-boiling-point polar solvents or templating agents, and runs at room temperature.…”

Section: Introductionmentioning

confidence: 99%

“…[29] However,H yP-NPs could be of interest also in imaging and tracking applications. [29] Compared with the preparation of other types of nanoparticles, such as traditional inorganic semiconductor quantum dots, metal NPs, or even inorganic perovskites, [30][31][32][33][34] the synthesis of HyP-NPs is not as well developed. [3,29] The wet-chemistry synthetic procedures reported to date are based on ac ommon strategy: the metal-halides ource and alkylammonium halides are dissolved in a" good" highly polar solvent and then injected into a" poor" nonpolars olvent that contains surfactants, such as oleic acid and oleylamine.…”

Section: Introductionmentioning

confidence: 99%

High‐Purity Hybrid Organolead Halide Perovskite Nanoparticles Obtained by Pulsed‐Laser Irradiation in Liquid

et al. 2016

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Nanoparticles of hybrid organic-inorganic perovskites have attracted a great deal of attention due to their variety of optoelectronic properties, their low cost, and their easier integration into devices with complex geometry, compared with microcrystalline, thin-film, or bulk metal halides. Here we present a novel one-step synthesis of organolead bromide perovskite nanocrystals based on pulsed-laser irradiation in a liquid environment (PLIL). Starting from a bulk CH NH PbBr crystal, our PLIL procedure does not involve the use of high-boiling-point polar solvents or templating agents, and runs at room temperature. The resulting nanoparticles are characterized by high crystallinity and are completely free of any microscopic product or organic coating layer. We also demonstrate the straightforward inclusion of laser-generated perovskite nanocrystals in a polymeric matrix to form a nanocomposite with single- and two-photon luminescence properties.

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An efficient and surface-benign purification scheme for colloidal nanocrystals based on quantitative assessment

Cited by 37 publications

References 46 publications

Resonance Raman Investigation of the Interaction between Aromatic Dithiocarbamate Ligands and CdSe Quantum Dots

Resonance Raman Investigation of the Interaction between Aromatic Dithiocarbamate Ligands and CdSe Quantum Dots

To Battle Surface Traps on CdSe/CdS Core/Shell Nanocrystals: Shell Isolation versus Surface Treatment

High‐Purity Hybrid Organolead Halide Perovskite Nanoparticles Obtained by Pulsed‐Laser Irradiation in Liquid

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