Uniform thickness and colloidal-stable CdS quantum disks with tunable thickness: Synthesis and properties

Zheng, Li; Qin, Haiyan; Guzun, D.; Benamara, Mourad; Salamo, Gregory J.; Peng, Xiaogang

doi:10.1007/s12274-012-0214-5

Cited by 107 publications

(158 citation statements)

References 52 publications

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“…Furthermore, regardless of sulfur composition, a new absorption peak emerged at the same wavelength (∼405 nm) in the absorption spectra of CdSe x S 1−x /CdS core/crown NPLs, which corresponds to the bandgap of 4 ML thick CdS NPLs. 23 These two findings strongly support that the synthesized CdSe x S 1−x core NPLs have a homogeneously alloyed structure with the same vertical thickness. Otherwise, we would observe a shifting in the excitonic features belonging to both core and crown regions.…”

Section: ■ Results and Discussionsupporting

confidence: 64%

Alloyed Heterostructures of CdSe_xS_1–x Nanoplatelets with Highly Tunable Optical Gain Performance

et al. 2017

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Here, we designed and synthesized alloyed heterostructures of CdSe x S1–x nanoplatelets (NPLs) using CdS coating in the lateral and vertical directions for the achievement of highly tunable optical gain performance. By using homogeneously alloyed CdSe x S1–x core NPLs as a seed, we prepared CdSe x S1–x /CdS core/crown NPLs, where CdS crown region is extended only in the lateral direction. With the sidewall passivation around inner CdSe x S1–x cores, we achieved enhanced photoluminescence quantum yield (PL-QY) (reaching 60%), together with increased absorption cross-section and improved stability without changing the emission spectrum of CdSe x S1–x alloyed core NPLs. In addition, we further extended the spectral tunability of these solution-processed NPLs with the synthesis of CdSe x S1–x /CdS core/shell NPLs. Depending on the sulfur composition of the CdSe x S1–x core and thickness of the CdS shell, CdSe x S1–x /CdS core/shell NPLs possessed highly tunable emission characteristics within the spectral range of 560–650 nm. Finally, we studied the optical gain performances of different heterostructures of CdSe x S1–x alloyed NPLs offering great advantages, including reduced reabsorption and spectrally tunable optical gain range. Despite their decreased PL-QY and reduced absorption cross-section upon increasing the sulfur composition, CdSe x S1–x based NPLs exhibit highly tunable amplified spontaneous emission performance together with low gain thresholds down to ∼53 μJ/cm2.

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Section: ■ Results and Discussionsupporting

confidence: 64%

Alloyed Heterostructures of CdSe_xS_1–x Nanoplatelets with Highly Tunable Optical Gain Performance

et al. 2017

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“…This discrepancy likely originates from lattice strain due to excess cadmium, terminating NS {100} basal planes. 28,30 Energy dispersive X-ray spectroscopy (EDXS) analyses of the sheets ( Figure 1e and Figure S3 To determine the conduction band positions of resulting NSs, electrochemical measurements were conducted as described in the Experimental Section. CdS NS electrodes were prepared by drop-casting samples onto fluorine doped tin oxide (FTO) substrates.…”

Section: Resultsmentioning

confidence: 99%

Efficient Photocatalytic Hydrogen Generation from Ni Nanoparticle Decorated CdS Nanosheets

et al. 2015

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High-quality, thickness-controlled CdS nanosheets (NSs) have been obtained through the thermal decomposition of cadmium diethyldithiocarbamate in octadecene. Ensembles with discrete thicknesses of 1.50, 1.80, and 2.16 nm have been made with corresponding lateral dimensions on the order of 90 nm × 20 nm. These latter values make the 1−3 nm NSs the largest 2D CdS specimens made to date using colloidal chemistry. Associated Ni nanoparticle decorated counterparts have been made through the photodeposition of Ni onto NSs with an average nanoparticle diameter of 6 nm. Subsequent photocatalytic hydrogen generation measurements have compared the performance of CdS NSs with that of their Ni NP decorated counterparts in water/ ethanol mixtures. Apparent quantum yields as large as 25% have been seen for Ni NP decorated NSs with transient yields as large as 64% within the first 2 h of irradiation. Results from ensemble femtosecond transient differential absorption spectroscopy reveal that the origin of this high efficiency stems from efficient electron transfer from CdS to Ni. In this regard, the CdS/Ni semiconductor/metal heterojunction acts to dissociate strongly bound excitons in CdS NSs, creating free carriers needed to carry out relevant reduction chemistries.

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“…It should be pointed out that Peng and co-workers 144 have successfully synthesized pure CdS nanodisks with similar optical properties as nanoplatelets 140 of four pure populations. In these syntheses, all the precursors including cadmium acetate dihydrate, sulfur and a fatty acid, are conjointly introduced in octadecene in a three-neck flask and are heated to various temperatures under inert atmosphere.…”

Section: Figure 23: Scheme Of Cde (E= S Se or Te) Nanocrystals "Seementioning

confidence: 99%

Two-Dimensional Colloidal Nanocrystals

et al. 2016

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Abstract:In this paper, we review recent progresses on colloidal growth of 2D nanocrystals.We identify four main sources of anisotropy which lead to the formation of plate-and sheetlike colloidal nanomaterials. Defect induced anisotropy is a growth method which relies on the presence of topological defects at the nanoscale to induce 2D shapes objects. Such a method is particularly important in the growth of metallic nanoobjects. Another way to induce anisotropy is based on ligand engineering. The availability of some nanocrystal facets can be tuned by selectively covering the surface with ligands of tunable thickness. Cadmium chalcogenides nanoplatelets (NPLs) strongly rely on this method which offers atomic control in the thinner direction, down to a few monolayers. 2D objects can also be obtained by post or in situ self-assembly of nanocrystals. This growth method differs from the previous ones in the sense that the elementary objects are not molecular precursors, and is a common method for lead chalcogenide compounds. Finally, anisotropy may simply rely on the lattice anisotropy itself as it is common for rod-like nanocrystals. Colloidally grown Transition Metal DiChalcogenides (TMDC) in particular result from such process. We also present hybrid syntheses which combine several of the previously described methods and other paths, such as cation exchange, which expand the range of available materials. Finally, we discuss in which sense 2D-objects differ from 0D nanocrystals and review some of their applications in optoelectronics, including lasing and photodetection, and biology.

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Uniform thickness and colloidal-stable CdS quantum disks with tunable thickness: Synthesis and properties

Cited by 107 publications

References 52 publications

Alloyed Heterostructures of CdSe_xS_1–x Nanoplatelets with Highly Tunable Optical Gain Performance

Alloyed Heterostructures of CdSe_xS_1–x Nanoplatelets with Highly Tunable Optical Gain Performance

Efficient Photocatalytic Hydrogen Generation from Ni Nanoparticle Decorated CdS Nanosheets

Two-Dimensional Colloidal Nanocrystals

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Uniform thickness and colloidal-stable CdS quantum disks with tunable thickness: Synthesis and properties

Cited by 107 publications

References 52 publications

Alloyed Heterostructures of CdSexS1–x Nanoplatelets with Highly Tunable Optical Gain Performance

Alloyed Heterostructures of CdSexS1–x Nanoplatelets with Highly Tunable Optical Gain Performance

Efficient Photocatalytic Hydrogen Generation from Ni Nanoparticle Decorated CdS Nanosheets

Two-Dimensional Colloidal Nanocrystals

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Alloyed Heterostructures of CdSe_xS_1–x Nanoplatelets with Highly Tunable Optical Gain Performance

Alloyed Heterostructures of CdSe_xS_1–x Nanoplatelets with Highly Tunable Optical Gain Performance