Cryogenic spectroscopy of ultra-low density colloidal lead chalcogenide quantum dots on chip-scale optical cavities towards single quantum dot near-infrared cavity QED

Bose, Ranojoy; Gao, Jie; McMillan, James F.; Williams, Alex D.; Wong, Chee Wei

doi:10.1364/oe.17.022474

Cited by 11 publications

(9 citation statements)

References 58 publications

(74 reference statements)

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“…On bare glass, single nanocrystals were more easily discernible with ~ 170 counts per millisecond, while on graphene, the photon counts from the single nanocrystals are lower, ~ 100 counts per millisecond. Photon collection at the individual or few nanocrystal level allows us to gain insight into the exciton radiative and non-radiative relaxation rates [22][23] which can be masked by ensemble inhomogeneous broadening. As shown by the circled points of interest in Figure 2, individual nanocrystals were selected for lifetime measurements.…”

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confidence: 99%

Time-resolved energy transfer from single chloride-terminated nanocrystals to graphene

Ajayi

Anderson

Cotlet

et al. 2014

Applied Physics Letters

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We examine the time-resolved resonance energy transfer of excitons from single n-butyl aminebound, chloride-terminated nanocrystals to two-dimensional graphene through time-correlated single photon counting. The radiative biexponential lifetime kinetics and blinking statistics of the individual surface-modified nanocrystal elucidate the non-radiative decay channels. Blinking modification as well as a 4 reduction in spontaneous emission were observed with the short chloride and n-butylamine ligands, probing the energy transfer pathways for the development of graphene-nanocrystal nanophotonic devices.

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confidence: 99%

Time-resolved energy transfer from single chloride-terminated nanocrystals to graphene

Ajayi

Anderson

Cotlet

et al. 2014

Applied Physics Letters

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“…Results reported in literature almost all refer to the lowest energy 1S h -1S e absorption feature. So far the results do not take into account the homogeneous and ensemble broadening of first exciton peak and its dispersive behavior, while it has been clearly shown that the few or single isolated near-infrared lead chalcogenide nanocrystals have a spectral broadening of ~ 100 meV at room temperature [25,26]. The broad-band spectral dispersion has not been rigorously examined in carrier multiplication studies and its related efficiencies, though recent studies [10,12,27,28] have examined the bleach dynamics at discrete wavelengths within only the first exciton transition.…”

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confidence: 99%

Ultrafast Supercontinuum Spectroscopy of Carrier Multiplication and Biexcitonic Effects in Excited States of PbS Quantum Dots

Gesuele

Sfeir

Koh³

et al. 2012

Nano Lett.

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We examine the multiple exciton population dynamics in PbS quantum dots by ultrafast spectrally-resolved supercontinuum transient absorption (SC-TA). We simultaneously probe the first three excitonic transitions over a broad spectral range. Transient spectra show the presence of first order bleach of absorption for the 1S h -1S e transition and second order bleach along with photoinduced absorption band for 1P h -1P e transition. We also report evidence of the one-photon forbidden 1S h,e -1P h,e transition. We examine signatures of carrier multiplication (multiexcitons for the single absorbed photon) from analysis of the first and second order bleaches, in the limit of low absorbed photon numbers ( abs N ~ 10 -2 ), at pump energies from two to four times the semiconductor band gap. The multiexciton generation efficiency is discussed both in terms of a broadband global fit and the ratio between early-to long-time transient absorption signals..Analysis of population dynamics shows that the bleach peak due to the biexciton population is red-shifted respect the single exciton one, indicating a positive binding energy.

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“…There are many motivations for working in the near infrared, two of the most important being integrating new technologies into the photonics industry, which uses the infrared regions around 1300 nm and 1550 nm, and the development of NCs suitable for in vivo biological imaging around 800 nm where tissues are most transparent and there is minimal bioluminescence. 195 With regard to photonics, there are many emerging technologies being developed for these regions, including photonic band-gap materials 202,203 and high-Q microcavities. 204 Therefore developing new NC materials that emit in these regions could potentially be compatible with some exciting new technologies and ultimately have a commercial impact on the photonics industry.…”

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confidence: 99%

Spectroscopy of single nanocrystals

2014

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As colloidal semiconductor nanocrystals are developed for a wider range of diverse applications, it becomes more important to gain a deeper understanding of their properties in order to direct synthetic efforts. While most synthetic developments are guided by changes in ensemble properties, certain applications such as those in nano-electronics and nano-photonics rely on properties of nanocrystals at the individual level. For such applications and even for a more detailed understanding of the ensemble behavior, single nanocrystal spectroscopy becomes a vital tool. This review looks at how single nanocrystal spectroscopy has been applied to materials based on modern synthetic techniques and how these studies are elucidating properties that remain hidden at the ensemble level. First, recent theoretical models that are important for understanding many observed phenomena are explored. Then the review highlights new insights into many of the photophysical properties that are of interest in semiconductor nanocrystal materials, such as the ubiquitous spectral instability, magneto-optical identification of the band-edge exciton fine structure, emission from multi-excitons, and the spectroscopic properties of charged nanocrystals that challenge long standing theories on photoluminescence blinking behavior. To date most of the research has been conducted on materials based on cadmium selenide primarily due to its many years of development as a prototypical nanocrystal system. The review ends with a discussion of new materials that would also benefit from a detailed photophysical understanding afforded by single nanocrystal spectroscopy.

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Cryogenic spectroscopy of ultra-low density colloidal lead chalcogenide quantum dots on chip-scale optical cavities towards single quantum dot near-infrared cavity QED

Cited by 11 publications

References 58 publications

Time-resolved energy transfer from single chloride-terminated nanocrystals to graphene

Time-resolved energy transfer from single chloride-terminated nanocrystals to graphene

Ultrafast Supercontinuum Spectroscopy of Carrier Multiplication and Biexcitonic Effects in Excited States of PbS Quantum Dots

Spectroscopy of single nanocrystals

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