Efficient Exciton Concentrators Built from Colloidal Core/Crown CdSe/CdS Semiconductor Nanoplatelets

Tessier, Martine; Spinicelli, Piernicola; Dupont, Dorian; Patriarche, G.; Ithurria, Sandrine; Dubertret, Benoît

doi:10.1021/nl403746p

Cited by 245 publications

(474 citation statements)

References 34 publications

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“…It is also important to note that, although we used highly uniform and rectangularshaped CdSe x S 1−x alloyed core NPLs as seeds, the formation of the CdS crown region was nonuniform in the lateral direction, which is typically observed for the CdSe/CdS core/crown NPLs in literature. 11,15,16 Compared to the CdSe x S 1−x core NPLs, CdSe x S 1−x /CdS core/crown NPLs exhibit substantially improved optical properties along with enhanced stability ( Figure S2). The absorption spectra of CdSe x S 1−x /CdS core/crown NPLs were presented in Figure 2b together with that of CdSe x S 1−x core NPLs for a better comparison.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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 Discussionmentioning

confidence: 99%

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

et al. 2017

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“…We have synthesized 4 monolayer (ML) CdSe NPLs as they have been most widely investigated in the literature 7,18,[35][36][37][38][39] and found applications in LED color-conversion layers, lasers and luminescent solar concentrators. We have used colloidal synthesis techniques similar to those used in ref.…”

Section: Resultsmentioning

confidence: 99%

Temperature-dependent optoelectronic properties of quasi-2D colloidal cadmium selenide nanoplatelets

et al. 2017

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Colloidal cadmium selenide (CdSe) nanoplatelets (NPLs) are a recently developed class of efficient luminescent nanomaterials suitable for optoelectronic device applications. A change in temperature greatly affects their electronic bandstructure and luminescence properties. It is important to understand how and why the characteristics of NPLs are influenced, particularly at elevated temperatures, where both reversible and irreversible quenching processes come into the picture. Here we present a study of the effect of elevated temperatures on the characteristics of colloidal CdSe NPLs. We used an effective-mass envelope function theory based 8-band k·p model and density-matrix theory considering exciton-phonon interaction. We observed the photoluminescence (PL) spectra at various temperatures for their photon emission energy, PL linewidth and intensity by considering the exciton-phonon interaction with both acoustic and optical phonons using Bose-Einstein statistical factors. With a rise in temperature we observed a fall in the transition energy (emission redshift), matrix element, Fermi factor and quasi Fermi separation, with a reduction in intraband state gaps and increased interband coupling. Also, there was a fall in the PL intensity, along with spectral broadening due to an intraband scattering effect. The predicted transition energy values and simulated PL spectra at varying temperatures exhibit appreciable consistency with the experimental results. Our findings have important implications for the application of NPLs in optoelectronic devices, such as NPL lasers and LEDs, operating much above room temperature.

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“…The preparation of cadmium myristate is followed by the recipe given in the literature. 30 Briefly, 1.23 g of cadmium nitrate tetrahydrate is dissolved in 40 mL of methanol, and 3.13 g of sodium myristate is dissolved in 250 mL of methanol. After complete dissolution, solutions are mixed and stirred strongly for around 1 h. Then, the solution is centrifuged and the precipitated part is dissolved in methanol.…”

Section: ■ Introductionmentioning

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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Efficient Exciton Concentrators Built from Colloidal Core/Crown CdSe/CdS Semiconductor Nanoplatelets

Cited by 245 publications

References 34 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

Temperature-dependent optoelectronic properties of quasi-2D colloidal cadmium selenide nanoplatelets

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

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Efficient Exciton Concentrators Built from Colloidal Core/Crown CdSe/CdS Semiconductor Nanoplatelets

Cited by 245 publications

References 34 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

Temperature-dependent optoelectronic properties of quasi-2D colloidal cadmium selenide nanoplatelets

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

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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