Synthesis of Metal–Selenide Nanocrystals Using Selenium Dioxide as the Selenium Precursor

Chen, Ou; Chen, Xian; Yang, Yongan; Lynch, Jared; Wu, Huimeng; Zhuang, Jiaqi; Cao, Y. Charles

doi:10.1002/anie.200804266

Cited by 195 publications

(209 citation statements)

References 17 publications

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“…The 195 different CQD materials were taken from approximately 24 CdS and CdSe preparations using procedures from the literature [31][32][33][34] and by taking aliquots during CQD growth. These CQD materials were purified according to the procedures reported with their syntheses.…”

Section: Methodsmentioning

confidence: 99%

A colloidal quantum dot spectrometer

Bao

Bawendi

2015

Nature

467

347

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Spectroscopy is carried out in almost every field of science, whenever light interacts with matter. Although sophisticated instruments with impressive performance characteristics are available, much effort continues to be invested in the development of miniaturized, cheap and easy-to-use systems. Current microspectrometer designs mostly use interference filters and interferometric optics that limit their photon efficiency, resolution and spectral range. Here we show that many of these limitations can be overcome by replacing interferometric optics with a two-dimensional absorptive filter array composed of colloidal quantum dots. Instead of measuring different bands of a spectrum individually after introducing temporal or spatial separations with gratings or interference-based narrowband filters, a colloidal quantum dot spectrometer measures a light spectrum based on the wavelength multiplexing principle: multiple spectral bands are encoded and detected simultaneously with one filter and one detector, respectively, with the array format allowing the process to be efficiently repeated many times using different filters with different encoding so that sufficient information is obtained to enable computational reconstruction of the target spectrum. We illustrate the performance of such a quantum dot microspectrometer, made from 195 different types of quantum dots with absorption features that cover a spectral range of 300 nanometres, by measuring shifts in spectral peak positions as small as one nanometre. Given this performance, demonstrable avenues for further improvement, the ease with which quantum dots can be processed and integrated, and their numerous finely tuneable bandgaps that cover a broad spectral range, we expect that quantum dot microspectrometers will be useful in applications where minimizing size, weight, cost and complexity of the spectrometer are critical.

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Section: Methodsmentioning

confidence: 99%

A colloidal quantum dot spectrometer

Bao

Bawendi

2015

Nature

467

347

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“…During last two decades, formation of metal chalcogenide QDs has been investigated using various trialkylphosphine chalcogenides (R3P=E; E= S, Se, Te) as precursors. [13][14]29,49,[66][67][68] In this context, the chemical identity of an important selenium precursor, which is prepared by dissolving elemental selenium in ODE at high temperature (>180 o C) and used frequently in CdSe QD synthesis 40,52,[69][70][71] has not been resolved.…”

Section: Investigation Of Thementioning

confidence: 99%

Mechanistic Study of the Formation of Bright White Light-Emitting Ultrasmall CdSe Nanocrystals: Role of Phosphine Free Selenium Precursors

Dolai¹,

Dutta

Muhoberac³

et al. 2015

Chem. Mater.

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ABSTRACT:We have designed a new non-phosphinated reaction pathway, which includes synthesis of a new, highly reactive Se-bridged organic species (chalcogenide precursor), to produce bright white light-emitting ultrasmall CdSe nanocrystals of high quality under mild reaction conditions. The detailed characterization of structural properties of the selenium precursor through combined 77 Se NMR and laser desorption ionization-mass spectrometry (LDI-MS) provided valuable insights into Se release and delineated the nanocrystal formation mechanism at the molecular level. The 1 H NMR study showed that the rate of disappearance of Se-precursor maintained a single-exponential decay with a rate constant of 2.3 x 10 -4 s -1 at room temperature. Furthermore, the combination of LDI-MS and optical spectroscopy was used for the first time to deconvolute the formation mechanism of our bright white light-emitting nanocrystals, which demonstrated initial formation of a smaller key nanocrystal intermediate (CdSe)19. Application of thermal driving force for destabilization resulted in (CdSe)n nanocrystal generation with n = 29-36 through continuous dissolution and addition of monomer onto existing nanocrystals while maintaining a living-polymerization type growth mode. Importantly, our ultrasmall CdSe nanocrystals displayed an unprecedentedly large fluorescence quantum yield of ~27% for this size regime (<2.0 nm diameter). These mixed oleylamine and cadmium benzoate ligand-coated CdSe nanocrystals showed a fluorescence lifetime of ~90 ns, a significantly large value for such small nanocrystals, which was due to delocalization of the exciton wavefunction into the ligand monolayer. We believe our findings will be relevant to formation of other metal chalcogenide nanocrystals through expansion of the understanding and manipulation of surface ligand chemistry, which together will allow the preparation of "artificial solids" with high charge conductivity and mobility for advanced solid-state device applications.3

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“…We use an empirical correction to account for detector afterpulsing [23], which would otherwise cause pð; Þ to artificially narrow on submillisecond time scales. Our samples, CdSe/(8 ML [24])CdS core [25]-shell [26] particles, exhibit room temperature emission centered at 640 nm and were chosen for their bright and stable fluorescence. Finally, the parameters of the PCFS experiment are optimized to focus exclusively on zerophonon line emission.…”

mentioning

confidence: 99%

Direct Observation of Rapid Discrete Spectral Dynamics in Single Colloidal CdSe-CdS Core-Shell Quantum Dots

et al. 2013

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We measure the anomalous spectral diffusion of single colloidal quantum dots over eight temporal decades simultaneously by combining single-molecule spectroscopy and photon-correlation Fourier spectroscopy. Our technique distinguishes between discrete and continuous dynamics and directly reveals that the quasicontinuous spectral diffusion observed using conventional spectroscopy is composed of rapid, discrete spectral jumps. Despite their multiple time scales, these dynamics can be captured by a single mechanism whose parameters vary widely between dots and over time in individual dots.

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Synthesis of Metal–Selenide Nanocrystals Using Selenium Dioxide as the Selenium Precursor

Cited by 195 publications

References 17 publications

A colloidal quantum dot spectrometer

A colloidal quantum dot spectrometer

Mechanistic Study of the Formation of Bright White Light-Emitting Ultrasmall CdSe Nanocrystals: Role of Phosphine Free Selenium Precursors

Direct Observation of Rapid Discrete Spectral Dynamics in Single Colloidal CdSe-CdS Core-Shell Quantum Dots

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