Double-crowned 2D semiconductor nanoplatelets with bicolor power-tunable emission

Guilloux, Victor; Gréboval, Charlie; Po, Hong; Makke, Lina; Fu, Ningyuan; Xu, Xiang; Patriarche, G.; Lhuillier, Emmanuel; Barisien, Thierry; Climente, Juan I.; Diroll, Benjamin T.; Ithurria, Sandrine

doi:10.1038/s41467-022-32713-2

Cited by 13 publications

(27 citation statements)

References 45 publications

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“…In 2020, Khan et al proposed the synthesis of CdSe/CdS/CdTe core/crown/crown NPLs, where, due to the CdS barrier between the core and the external crown, the exciton can both recombine in these two materials and also recombine with a tunneling effect at the “pseudo” interface between CdSe and CdTe. Even more recently, in 2022, Dabard et al synthesized CdSe/CdTe/CdSe core/crown/crown NPLs where the exciton recombines at the interface between the first crown and CdSe, or in the second CdSe crown leading to dual emission in the green and the red …”

Section: Synthesis and Structure Of Nplsmentioning

confidence: 99%

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2D II–VI Semiconductor Nanoplatelets: From Material Synthesis to Optoelectronic Integration

Diroll

Güzeltürk

et al. 2023

Chem. Rev.

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The field of colloidal synthesis of semiconductors emerged 40 years ago and has reached a certain level of maturity thanks to the use of nanocrystals as phosphors in commercial displays. In particular, II−VI semiconductors based on cadmium, zinc, or mercury chalcogenides can now be synthesized with tailored shapes, composition by alloying, and even as nanocrystal heterostructures. Fifteen years ago, II−VI semiconductor nanoplatelets injected new ideas into this field. Indeed, despite the emergence of other promising semiconductors such as halide perovskites or 2D transition metal dichalcogenides, colloidal II−VI semiconductor nanoplatelets remain among the narrowest room-temperature emitters that can be synthesized over a wide spectral range, and they exhibit good material stability over time. Such nanoplatelets are scientifically and technologically interesting because they exhibit optical features and production advantages at the intersection of those expected from colloidal quantum dots and epitaxial quantum wells. In organic solvents, gram-scale syntheses can produce nanoparticles with the same thicknesses and optical properties without inhomogeneous broadening. In such nanoplatelets, quantum confinement is limited to one dimension, defined at the atomic scale, which allows them to be treated as quantum wells. In this review, we discuss the synthetic developments, spectroscopic properties, and applications of such nanoplatelets. Covering growth mechanisms, we explain how a thorough understanding of nanoplatelet growth has enabled the development of nanoplatelets and heterostructured nanoplatelets with multiple emission colors, spatially localized excitations, narrow emission, and high quantum yields over a wide spectral range. Moreover, nanoplatelets, with their large lateral extension and their thin short axis and low dielectric surroundings, can support one or several electron−hole pairs with large exciton binding energies. Thus, we also discuss how the relaxation processes and lifetime of the carriers and excitons are modified in nanoplatelets compared to both spherical quantum dots and epitaxial quantum wells. Finally, we explore how nanoplatelets, with their strong and narrow emission, can be considered as ideal candidates for pure-color light emitting diodes (LEDs), strong gain media for lasers, or for use in luminescent light concentrators.

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Section: Synthesis and Structure Of Nplsmentioning

confidence: 99%

“…Additionally, the inhomogeneous broadening in these heterostructures is associated with the compositional variations at the nanoscale. Double-crown CdSe/CdTe/CdSe NPLs have also been developed with a double emission feature that can be used in LEDs as a voltage-tunable electroluminescence spectrum …”

Section: Synthesis and Structure Of Nplsmentioning

confidence: 99%

2D II–VI Semiconductor Nanoplatelets: From Material Synthesis to Optoelectronic Integration

Diroll

Güzeltürk

et al. 2023

Chem. Rev.

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“…On the other hand, the growth of the CdSe crown increases QY up to 83%. We intentionally choose a smaller size for the multi-crowned NPLs because large-sized NPLs tend to twist and roll to reduce their surface energy, as previously reported in the literature. − Rolled or twisted NPLs can significantly hinder obtaining homogeneous NPL film formation, an essential requirement for fabricating high-performance optical devices …”

Section: Resultsmentioning

confidence: 99%

“…17,29,31 Recently, advanced heterostructures such as core/crown/ crown, core@gradient-shell, core@shell@shell, and platelet-inbox have been reported to enhance the optical properties. 6,11,19,21,32,33 For example, CdSe/CdS/CdTe core/crown/ crown NPLs enable dual emission by employing a CdS barrier layer between the core CdSe and outer crown CdTe. 32 CdSe/ CdSe 1−x Te x /CdS core/crown/crown heterostructures of type-II electronic band alignment are capable of exhibiting increased absorption cross-section, large gain coefficients, and reduced stacking formation.…”

Section: Introductionmentioning

confidence: 99%

High External Quantum Efficiency Light-Emitting Diodes Enabled by Advanced Heterostructures of Type-II Nanoplatelets

Durmuşoğlu

Hernández‐Martínez

et al. 2023

ACS Nano

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Colloidal quantum wells (CQWs), also known as nanoplatelets (NPLs), are exciting material systems for numerous photonic applications, including lasers and light-emitting diodes (LEDs). Although many successful type-I NPL-LEDs with high device performance have been demonstrated, type-II NPLs are not fully exploited for LED applications, even with alloyed type-II NPLs with enhanced optical properties. Here, we present the development of CdSe/CdTe/CdSe core/crown/crown (multi-crowned) type-II NPLs and systematic investigation of their optical properties, including their comparison with the traditional core/crown counterparts. Unlike traditional type-II NPLs such as CdSe/CdTe, CdTe/CdSe, and CdSe/CdSe x Te1–x core/crown heterostructures, here the proposed advanced heterostructure reaps the benefits of having two type-II transition channels, resulting in a high quantum yield (QY) of 83% and a long fluorescence lifetime of 73.3 ns. These type-II transitions were confirmed experimentally by optical measurements and theoretically using electron and hole wave function modeling. Computational study shows that the multi-crowned NPLs provide a better-distributed hole wave function along the CdTe crown, while the electron wave function is delocalized in the CdSe core and CdSe crown layers. As a proof-of-concept demonstration, NPL-LEDs based on these multi-crowned NPLs were designed and fabricated with a record high external quantum efficiency (EQE) of 7.83% among type-II NPL-LEDs. These findings are expected to induce advanced designs of NPL heterostructures to reach a fascinating level of performance, especially in LEDs and lasers.

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“…Recently, more sophisticated heterostructures have been developed for type‐II nanoplatelets with two crowns being grown on the seed core. [ 18 ] Khan et al. [ 19 ] proposed a two‐crown heterostructure in which the intermediate crown of CdS acts as an electron barrier that inhibits the propagation of the electrons into the outermost CdTe crown.…”

Section: Introductionmentioning

confidence: 99%

Gradient Type‐II CdSe/CdSeTe/CdTe Core/Crown/Crown Heteronanoplatelets with Asymmetric Shape and Disproportional Excitonic Properties

Shabani

Hernández‐Martínez

Shermet

et al. 2023

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Characterized by their strong 1D confinement and long‐lifetime red‐shifted emission spectra, colloidal nanoplatelets (NPLs) with type‐II electronic structure provide an exciting ground to design complex heterostructures with remarkable properties. This work demonstrates the synthesis and optical characterization of CdSe/CdSeTe/CdTe core/crown/crown NPLs having a step‐wise gradient electronic structure and disproportional wavefunction distribution, in which the excitonic properties of the electron and hole can be finely tuned through adjusting the geometry of the intermediate crown. The first crown with staggered configuration gives rise to a series of direct and indirect transition channels that activation/deactivation of each channel is possible through wavefunction engineering. Moreover, these NPLs allow for switching between active channels with temperature, where lattice contraction directly affects the electron–hole (e–h) overlap. Dominated by the indirect transition channels over direct transitions, the lifetime of the NPLs starts to increase at 9 K, indicative of low dark‐bright exciton splitting energy. The charge transfer states from the two type‐II interfaces promote a large number of indirect transitions, which effectively increase the absorption of low‐energy photons critical for nonlinear properties. As a result, these NPLs demonstrate exceptionally high two‐photon absorption cross‐sections with the highest value of 12.9 × 106 GM and superlinear behavior.

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Double-crowned 2D semiconductor nanoplatelets with bicolor power-tunable emission

Cited by 13 publications

References 45 publications

2D II–VI Semiconductor Nanoplatelets: From Material Synthesis to Optoelectronic Integration

2D II–VI Semiconductor Nanoplatelets: From Material Synthesis to Optoelectronic Integration

High External Quantum Efficiency Light-Emitting Diodes Enabled by Advanced Heterostructures of Type-II Nanoplatelets

Gradient Type‐II CdSe/CdSeTe/CdTe Core/Crown/Crown Heteronanoplatelets with Asymmetric Shape and Disproportional Excitonic Properties

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