Optical Properties of Semiconductor Nanocrystals

Гапоненко, С. В.

doi:10.1017/cbo9780511524141

Cited by 745 publications

(677 citation statements)

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“…[19] However, it is clear that the slope of the curves in Figure 4 should increase with increasing quantum numbers of the orbitals involved, which is exactly what is observed. Furthermore, the slope of the different transitions is also determined by the effective masses of electrons and holes.…”

Section: Resultssupporting

confidence: 68%

“…As was mentioned above, the energies of transitions a to z increase (nearly) linearly with D À1.5 and extrapolate to 0.28 eV, with an increasing slope for higher energy transitions. Effective mass theory yields the following expression [19][20][21] for interband transitions with electrons and holes in the same orbitals (e.g. 1S h 1S e , 1P h 1P e , …):…”

Section: Resultsmentioning

confidence: 99%

“…[19] E g , " h, e, and e in correspond to the fundamental bandgap, Planck s constant, the electronic charge, and the dielectric constant inside the nanocrystal, respectively. Neglecting the last term (because of the high e in of PbSe), we find the following slope of the energy with respect to D À2 :…”

Section: Resultsmentioning

confidence: 99%

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Optical Investigation of Quantum Confinement in PbSe Nanocrystals at Different Points in the Brillouin Zone

Koole

Allan

Delerue

et al. 2008

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We present detailed investigations on the optical properties of PbSe nanocrystals. The absorption spectra of monodisperse, quasispherical nanocrystals exhibit sharp features as a result of distinct optical transitions. To study the size dependence, absorption spectra of nanocrystals ranging from 3.4 to 10.9 nm in diameter are analysed and a total of 11 distinct optical transitions are identified. The assignment of the various optical transitions is discussed and compared to theoretically calculated transition energies. By plotting all transitions as a function of nanocrystal size (D) we find that the energy (E) changes with the following relationship E / D À1.5 for the lowest energy transitions. The transition energy extrapolates to approximately 0.3 eV for infinite crystal size, in agreement with the bandgap of bulk PbSe at the L-point in the Brillouin zone. In addition, high-energy transitions are observed, which extrapolate to 1.6 eV for infinite crystal size, which is in good agreement with the bulk bandgap of PbSe at the S-point in the Brillouin zone. Tight-binding calculations confirm that the high-energy transitions originate from the S-point in the Brillouin zone. The S-character of the high-energy transitions may be of importance to explain the mechanism behind multiple exciton generation in PbSe nanocrystals.

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Section: Resultssupporting

confidence: 68%

Section: Resultsmentioning

confidence: 99%

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Optical Investigation of Quantum Confinement in PbSe Nanocrystals at Different Points in the Brillouin Zone

Koole

Allan

Delerue

et al. 2008

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“…Interested readers should consult textbooks on quantum mechanics, solid-state physics, or QDs (Atkins and Friedman 1997;Gaponenko 1998;Kittel 1996) for an in-depth discussion.…”

Section: Quantum Dots: Semiconductor Systems Of Reduced Dimensionalitymentioning

confidence: 99%

Quantum Optics: Colloidal Fluorescent Semiconductor Nanocrystals (Quantum Dots) in Single-Molecule Detection and Imaging

Bentolila

Michalet

Weiss

2008

Single Molecules and Nanotechnology

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Coming from the electronic material sciences, semiconductor nanocrystals, called quantum dots (QDs), have emerged as new powerful fluorescent probes for in vitro and in vivo biological labeling and single-molecule experiments. QDs possess several unique optical properties that make them very attractive over conventional fluorescent dyes and genetically encoded proteins technologies. They have precise emission color tunability by size due to quantum confinement effects, better photostability and brightness, wide absorption band and very narrow emission band for multiplexing, and increased fluorescence lifetimes. These characteristics, combined with some dramatic progresses achieved in surface chemistry, biocompatibility and targeting strategies have allowed their recent advances in the field of single-molecule detection and imaging

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“…We note that another means of decreasing the recombination probability of photogenerated electrons and holes in these devices relies on surface passivation of the NCs. 1 Indeed, charges encounter high potential barriers due to the ligands passivating the NCs' surface. During the film assembly, the NC solution was rigorously stirred to prevent precipitation.…”

mentioning

confidence: 99%

Photosensitivity Enhancement with TiO₂ in Semitransparent Light-Sensitive Skins of Nanocrystal Monolayers

Akhavan

Yeltik

Demir

2014

ACS Appl. Mater. Interfaces

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ABSTRACT:We propose and demonstrate light-sensitive nanocrystal skins that exhibit broadband sensitivity enhancement based on electron transfer to a thin TiO 2 film grown by atomic layer deposition. In these photosensors, which operate with no external bias, photogenerated electrons remain trapped inside the nanocrystals. These electrons generally recombine with the photogenerated holes that accumulate at the top interfacing contact, which leads to lower photovoltage buildup. Because favorable conduction band offset aids in transferring photoelectrons from CdTe nanocrystals to the TiO 2 layer, which decreases the exciton recombination probability, TiO 2 has been utilized as the electron-accepting material in these lightsensitive nanocrystal skins. A controlled interface thickness between the TiO 2 layer and the monolayer of CdTe nanocrystals enables a photovoltage buildup enhancement in the proposed nanostructure platform. With TiO 2 serving as the electron acceptor, we observed broadband sensitivity improvement across 350−475 nm, with an approximately 22% enhancement. Furthermore, time-resolved fluorescence measurements verified the electron transfer from the CdTe nanocrystals to the TiO 2 layer in light-sensitive skins. These results could pave the way for engineering nanocrystal-based light-sensing platforms, such as smart transparent windows, light-sensitive walls, and large-area optical detection systems.

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Optical Properties of Semiconductor Nanocrystals

Cited by 745 publications

References 0 publications

Optical Investigation of Quantum Confinement in PbSe Nanocrystals at Different Points in the Brillouin Zone

Optical Investigation of Quantum Confinement in PbSe Nanocrystals at Different Points in the Brillouin Zone

Quantum Optics: Colloidal Fluorescent Semiconductor Nanocrystals (Quantum Dots) in Single-Molecule Detection and Imaging

Photosensitivity Enhancement with TiO₂ in Semitransparent Light-Sensitive Skins of Nanocrystal Monolayers

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Optical Properties of Semiconductor Nanocrystals

Cited by 745 publications

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Optical Investigation of Quantum Confinement in PbSe Nanocrystals at Different Points in the Brillouin Zone

Optical Investigation of Quantum Confinement in PbSe Nanocrystals at Different Points in the Brillouin Zone

Quantum Optics: Colloidal Fluorescent Semiconductor Nanocrystals (Quantum Dots) in Single-Molecule Detection and Imaging

Photosensitivity Enhancement with TiO2 in Semitransparent Light-Sensitive Skins of Nanocrystal Monolayers

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Photosensitivity Enhancement with TiO₂ in Semitransparent Light-Sensitive Skins of Nanocrystal Monolayers