Laser-annealing-made amplified spontaneous emission of “giant” CdSe/CdS core/shell nanocrystals transferred from bulk-like shell to quantum-confined core

Liao, Chen; Fan, Kai; Xu, Ruilin; Zhang, Huichao; Lü, Changgui; Cui, Yiping; Zhang, Jiayu

doi:10.1364/prj.3.000200

Cited by 21 publications

(29 citation statements)

References 17 publications

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“…These findings give a rationale to the role of the shell volume and of the core/shell interface and thus provide a further insight into the physics of dual emission so far reported in the literature. All dual-emitting NCs described in the literature are characterized by a large volume of the shell [2,16,19,20,22,23] or of part of the structures, like the pods in tetrapods [12][13][14]17], or the rod shell in dot/rod NCs [12,15], in agreement with our conclusions. Here, in addition, we provide information on the role of the core/shell interface in exciton relaxation and describe the dynamical physical processes and the excited-state evolution as a function of time and excitation conditions.…”

Section: Transient Transmission Measurementssupporting

confidence: 91%

“…Multiple emission originating from a single particle is advantageous, compared to that from multiple particles, because it results in internally referenced signals, reduction of the impact of external factors, higher detection efficiency, and higher probe concentration [3]. Dual emission in NCs has been obtained mainly through two strategies: ion doping, e.g., copper, manganese, or silver [3][4][5][7][8][9][10], and synthesis of specific heterostructures [2,6,[11][12][13][14][15][16][17][18][19][20][21][22][23]. NC heterostructures can be grown in mainly four different morphologies: multiple-shell NCs [6,11,18,21], tetrapods [12][13][14]17], dot in rod [11,15], and "giant" or "big volume" shell NCs [2,16,19,20,22,23].…”

Section: Introductionmentioning

confidence: 99%

“…Very intriguing is the case of the other configurations, which are composed of only two materials (dot core and pods, dot core and rod-shaped shell, dot core and big shell). Here, one emission line originates from core excitons, while the second emission line has been ascribed to trap states [6,17,19], excitons in the pods or in the shell confined by a potential barrier [13,16,20,22,23], or a saturation effect [15,22]. Shell emission seems favored by long pod or rod and large shell volume [12,14,15,19], where usually nonradiative Auger recombination is reduced or suppressed [12,16,18,24].…”

Section: Introductionmentioning

confidence: 99%

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Dual emission and optical gain in PbS/CdS nanocrystals: Role of shell volume and of core/shell interface

et al. 2017

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Colloidal semiconductor nanocrystals (NCs) emitting simultaneously at two distinct wavelengths are of great interest for multiple applications ranging from ultrasensitive self-calibrating nanoscale sensing to light-emitting diodes and white-light emission. The physical mechanism governing dual emission in core/shell NCs composed of two materials is still under investigation; in particular, the roles of the volume of the shell and of the core/shell interface are not well understood. Here we compare three different PbS/CdS NCs with identical cores, but shells of different thicknesses and different core/shell interfaces. We study photoluminescence (PL) characteristics and ultrafast exciton dynamics with subpicosecond time resolution. We find that dual emission is possible for both thick and thin quantum-confined shells, and for different core/shell interfaces. We show that very thick shells allow the decoupling of shell excitons from core ones and we fully describe the dynamic exciton barrier, connected to efficient shell PL. We discuss the efficiency of shell PL in relation to the properties of the NCs and show that it can give rise to optical gain. Our results provide a comprehensive understanding of the physical phenomena governing dual-emission mechanisms in NCs.

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Section: Transient Transmission Measurementssupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Dual emission and optical gain in PbS/CdS nanocrystals: Role of shell volume and of core/shell interface

et al. 2017

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“…We start our measurements with femtosecond 400 nm pulsed excitation, which corresponds to excitation of primarily shell-based states. In more traditional giant CdSe/CdS NCs, this type of excitation usually results in the ASE from the core states, that become quickly populated by holes relaxing from the shell on the subps time scale. , In sharp contrast, in both DiB samples, ASE is observed not from the core but the shell states (Figure a,b). This is a direct result of a considerable extension of the shell-hole lifetime, which becomes sufficiently long to support the development of the avalanche of the stimulated-emission photons.…”

Section: Resultsmentioning

confidence: 97%

Effect of Core/Shell Interface on Carrier Dynamics and Optical Gain Properties of Dual-Color Emitting CdSe/CdS Nanocrystals

et al. 2016

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Two-color emitting colloidal semiconductor nanocrystals (NCs) are of interest for applications in multimodal imaging, sensing, lighting, and integrated photonics. Dual color emission from core- and shell-related optical transitions has been recently obtained using so-called dot-in-bulk (DiB) CdSe/CdS NCs comprising a quantum-confined CdSe core embedded into an ultrathick (∼7-9 nm) CdS shell. The physical mechanism underlying this behavior is still under debate. While a large shell volume appears to be a necessary condition for dual emission, comparison between various types of thick-shell CdSe/CdS NCs indicates a critical role of the interface "sharpness" and the presence of potential barriers. To elucidate the effect of the interface morphology on the dual emission, we perform side-by-side studies of CdSe/CdS DiB-NCs with nominally identical core and shell dimensions but different structural properties of the core/shell interface arising from the crystal structure of the starting CdSe cores (zincblende vs wurtzite). While both structures exhibit dual emission under comparable pump intensities, NCs with a zincblende core show a faster growth of shell luminescence with excitation fluence and a more readily realized regime of amplified spontaneous emission (ASE) even under "slow" nanosecond excitation. These distinctions can be linked to the structure of the core/shell interface: NCs grown from the zincblende cores contain a ∼3.5 nm thick zincblende CdS interlayer, which separates the core from the wurtzite CdS shell and creates a potential barrier for photoexcited shell holes inhibiting their relaxation into the core. This helps maintain a higher population of shell states and simplifies the realization of dual emission and ASE involving shell-based optical transitions.

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“…Femtosecond laser ablation has become crucial because it has a large amount of practical applications in numerous scientific [1][2][3][4], medical [5,6], and industrial fields [7]. However, the potential is still limited because of the complexity of the ablation process, which involves various mechanisms such as energy deposition [8,9], energy transfer [10], and energy relaxation [11]. During the ablation process, energy deposition from the laser to material is crucial because it determines ablation results.…”

Section: Introductionmentioning

confidence: 99%

Direct observation of structure-assisted filament splitting during ultrafast multiple-pulse laser ablation

Wang¹,

Pan²,

Sun³

et al. 2019

Opt. Express

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Laser-induced plasma evolution in fused silica through multipulse laser ablation was studied using pump-probe technology. Filament splitting was observed in the early stage of plasma evolution (before ~300 fs). This phenomenon can be attributed to competition between laser divergent propagation induced by a pre-pulse-induced crater and the nonlinear self-focusing effect. This effect was validated through simulation results. With the increasing pulse number, the appearance of filament peak electron density was postponed. Furthermore, a second peak in the filament and peak position separation were observed because of an optical path difference between the lasers propagating from the crater center and edge. The experimental results revealed the influence of a prepulse-induced structure on the energy distribution of subsequent pulses, which are essential for understanding the mechanism of laser-material interactions, particularly in ultrafast multiple-pulse laser ablation.

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Laser-annealing-made amplified spontaneous emission of “giant” CdSe/CdS core/shell nanocrystals transferred from bulk-like shell to quantum-confined core

Cited by 21 publications

References 17 publications

Dual emission and optical gain in PbS/CdS nanocrystals: Role of shell volume and of core/shell interface

Dual emission and optical gain in PbS/CdS nanocrystals: Role of shell volume and of core/shell interface

Effect of Core/Shell Interface on Carrier Dynamics and Optical Gain Properties of Dual-Color Emitting CdSe/CdS Nanocrystals

Direct observation of structure-assisted filament splitting during ultrafast multiple-pulse laser ablation

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