Optimized Synthesis of CdTe Nanoplatelets and Photoresponse of CdTe Nanoplatelets Films

Pedetti, Silvia; Nadal, Brice; Lhuillier, Emmanuel; Mahler, Benoît; Bouet, Cécile; Abécassis, Benjamin; Xu, Xiujuan; Dubertret, Benoît

doi:10.1021/cm4006844

Cited by 108 publications

(196 citation statements)

References 46 publications

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“…However, we failed to prepare 5 ML thick CdTe NPLs by following the protocol described in ref. 31. Nevertheless, we were able to synthesize 4 ML normal CdSe (core)-CdTe(wings) and inverted CdTe (core)-CdSe-(wings) hetero-NPLs ( Fig.…”

Section: Resultsmentioning

confidence: 98%

“…At the same time semiconductor NCs with 1D quantum confinement (quantum nanoplatelets, NPLs) composed of cadmium chalcogenides are currently being extensively studied [28][29][30][31][32] and expected to be promising materials for the preparation of semiconductor HNCs with efficient charge separation. Such NPLs exhibit electronic and optical properties that differ from those for QDs, such as much narrower absorption and PL bands (FWHM < 10 nm), a giant oscillator strength, lower thresholds for amplified spontaneous emission and higher optical gain saturation.…”

Section: Introductionmentioning

confidence: 99%

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Colloidal synthesis and optical properties of type-II CdSe–CdTe and inverted CdTe–CdSe core–wing heteronanoplatelets

et al. 2015

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We developed colloidal synthesis to investigate the structural and electronic properties of CdSe-CdTe and inverted CdTe-CdSe heteronanoplatelets and experimentally demonstrate that the overgrowth of cadmium selenide or cadmium telluride core nanoplatelets with counterpartner chalcogenide wings leads to type-II heteronanoplatelets with emission energies defined by the bandgaps of the CdSe and CdTe platelets and the characteristic band offsets. The observed conduction and valence band offsets of 0.36 eV and 0.56 eV are in line with theoretical predictions. The presented type-II heteronanoplatelets exhibit efficient spatially indirect radiative exciton recombination with a quantum yield as high as 23%.While the exciton lifetime is strongly prolonged in the investigated type-II 2D systems with respect to 2D type-I systems, the occurring 2D giant oscillator strength (GOST) effect still leads to a fast and efficient exciton recombination. This makes type-II heteronanoplatelets interesting candidates for low threshold lasing applications and photovoltaics.

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Section: Resultsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Colloidal synthesis and optical properties of type-II CdSe–CdTe and inverted CdTe–CdSe core–wing heteronanoplatelets

et al. 2015

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“…In addition, an absorption feature appearing within the spectral region of 550−560 nm emerges and becomes comparable to the electron/light-hole and electron/heavy-hole transitions of CdSe NPLs as the CdTe crown is grown larger. This red-shifted sharp absorption peak (∼556 nm) thus corresponds to the formation of excitons in the 4 ML thick CdTe crown layer, 35 and the intensity of this peak can be tuned by changing the size of the CdTe crown layer. Also, it was shown that higher concentration of OA results in formation of extended CdTe crown region and enhances the absorption of crown region.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Type-II Colloidal Quantum Wells: CdSe/CdTe Core/Crown Heteronanoplatelets

et al. 2015

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Solution-processed quantum wells, also known as colloidal nanoplatelets (NPLs), are emerging as promising materials for colloidal optoelectronics. In this work, we report the synthesis and characterization of CdSe/CdTe core/crown NPLs exhibiting a Type-II electronic structure and Type-II specific optical properties. Here, based on a core-seeded approach, the CdSe/CdTe core/crown NPLs were synthesized with well-controlled CdTe crown coatings. Uniform and epitaxial growth of CdTe crown region was verified by using structural characterization techniques including transmission electron microscopy (TEM) with quantitative EDX analysis and X-ray diffraction (XRD). Also the optical properties were systematically studied in these Type-II NPLs that reveal strongly red-shifted photoluminescence (up to ∼150 nm) along with 2 orders of magnitude longer fluorescence lifetimes (up to 190 ns) compared to the Type-I NPLs owing to spatially indirect excitons at the Type-II interface between the CdSe core and the CdTe crown regions. Photoluminescence excitation spectroscopy confirms that this strongly red-shifted emission actually arises from the CdSe/CdTe NPLs. In addition, temperature-dependent time-resolved fluorescence spectroscopy was performed to reveal the temperature-dependent fluorescence decay kinetics of the Type-II NPLs exhibiting interesting behavior. Also, water-soluble Type-II NPLs were achieved via ligand exchange of the CdSe/CdTe core/crown NPLs by using 3-mercaptopropionic acid (MPA), which allows for enhanced charge extraction efficiency owing to their shorter chain length and enables high quality film formation by layer-by-layer (LBL) assembly. With all of these appealing properties, the CdSe/CdTe core/crown heterostructures having Type-II electronic structure presented here are highly promising for light-harvesting applications.

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“…140,142 CdS nanoplates come with a large lateral extension. Compared to CdSe, their optical absorption is broader.…”

Section: Figure 21: Tem Images Of Cdse Npls With Small (A) and Large mentioning

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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Optimized Synthesis of CdTe Nanoplatelets and Photoresponse of CdTe Nanoplatelets Films

Cited by 108 publications

References 46 publications

Colloidal synthesis and optical properties of type-II CdSe–CdTe and inverted CdTe–CdSe core–wing heteronanoplatelets

Colloidal synthesis and optical properties of type-II CdSe–CdTe and inverted CdTe–CdSe core–wing heteronanoplatelets

Type-II Colloidal Quantum Wells: CdSe/CdTe Core/Crown Heteronanoplatelets

Two-Dimensional Colloidal Nanocrystals

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