Isolation of the Magic‐Size CdSe Nanoclusters [(CdSe)13(n‐octylamine)13] and [(CdSe)13(oleylamine)13]

Wang, Yuanyuan; Liu, Yi Hsin; Zhang, Ying; Wang, Fudong; Kowalski, Paul; Rohrs, Henry W.; Loomis, Richard A.; Gross, Michael L.; Buhro, William E.

doi:10.1002/anie.201202380

Cited by 135 publications

(239 citation statements)

References 16 publications

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“…This lack could be due to their relatively low stability in comparison to other magic-sized nanocrystals such as (CdSe)13 and (CdSe)33/34. 60,63 It should be mentioned that the broadness of the LDI-MS peak (covering 5.5-7.5 kDa) could be due to formation of other MSNs during the laser ablation as had earlier been reported. 60 Until now the literature have reported that exclusive formation of single-sized MSNs such as (CdSe)13, (CdSe)34, or (CdSe)56 has only been observed at room temperature.…”

Section: Resultsmentioning

confidence: 70%

“…60,63 It should be mentioned that the broadness of the LDI-MS peak (covering 5.5-7.5 kDa) could be due to formation of other MSNs during the laser ablation as had earlier been reported. 60 Until now the literature have reported that exclusive formation of single-sized MSNs such as (CdSe)13, (CdSe)34, or (CdSe)56 has only been observed at room temperature. 41,60,63 Upon heating these nanocrystals at moderately high temperature (>100 0 C), RNCs were formed, which is due to destabilization of MSNs by overcoming the energy barrier.…”

Section: Resultsmentioning

confidence: 70%

“…60 Until now the literature have reported that exclusive formation of single-sized MSNs such as (CdSe)13, (CdSe)34, or (CdSe)56 has only been observed at room temperature. 41,60,63 Upon heating these nanocrystals at moderately high temperature (>100 0 C), RNCs were formed, which is due to destabilization of MSNs by overcoming the energy barrier. Figure 2B shows the UV-vis spectra of the our reaction mixture containing (CdSe)19 nanocrystals at 60 0 C. Interestingly, with time not only did the band-edge peak red-shift but also the peak intensity decrease.…”

Section: Resultsmentioning

confidence: 99%

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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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Section: Resultsmentioning

confidence: 70%

Section: Resultsmentioning

confidence: 70%

Section: Resultsmentioning

confidence: 99%

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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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“…As a distinct state of matter, MSCNs belong to the interesting intersection region between molecular and larger nanocrystals. [1][2][3][4][5][6][7][8][9] Due to the unique structures and/or composition configuration, as well as thermodynamic stability compared to nanocrystals, MSNCs often show exotic chemical and physical properties. 8,[10][11][12] In addition, MSCNs with high-stability and exactly same size, can form so called "cluster assembled materials", 13,14 providing a promising approach for the design of nano-devices.…”

Section: Introductionmentioning

confidence: 99%

Evolution of Self-Assembled ZnTe Magic-Sized Nanoclusters

et al. 2015

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Three families of ZnTe magic-sized nanoclusters (MSNCs) were obtained exclusively using polytellurides as a tellurium precursor in a one-pot reaction by simply varying the reaction temperature and time only. Different ZnTe MSNCs exhibit different self-assembling or aggregation behavior, owing to their different structure, cluster size, and dipole-dipole interactions. The smallest family of ZnTe MSNCs (F323) does not reveal a crystalline structure and as a result assembles into lamellar triangle plates. Continuous heating of as synthesized ZnTe F323 assemblies resulted in the formation of ZnTe F398 MSNCs with wurzite structure and concomitant transformation into lamellar rectangle assemblies with the organization of nanoclusters along the ⟨002⟩ direction. Further annealing of ZnTe F398 assembled lamellar rectangles leads to full organization of MSNCs in all directions and formation of larger ZnTe F444 NCs that spontaneously form ultrathin nanowires following an oriented attachment mechanism. The key step in control over the size distribution of ZnTe ultrathin nanowires is, in fact, the growth mechanism of ZnTe F398 MSNCs; namely, the step growth mechanism enables formation of more uniform nanowires compared to those obtained by continuous growth mechanism. High yield of ZnTe nanowires is achieved as a result of the wurzite structure of F398 precursor. Transient absorption (TA) measurements show that all three families possess ultrafast dynamics of photogenerated electrons, despite their different crystalline structures.

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“…At 3E g the hybridized states in both VB and CB contributed equally to electron-phonon couplings in both ligated systems, and the relaxation rates became nearly identical between the two systems at this excitation energy. It may be interesting to apply these methods to the experimentally created magic sized CdSe clusters terminated with thiols and amines [58,139].…”

Section: Ligands Contribute High-frequency Phonon Modesmentioning

confidence: 99%

Time-domain ab initio modeling of excitation dynamics in quantum dots

Neukirch¹,

Hyeon‐Deuk²,

Prezhdo³

2014

Coordination Chemistry Reviews

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The review discusses the results of ab initio time-dependent density functional theory and nonadiabatic molecular dynamics simulations of photoinduced dynamics of charges, excitons, plasmons, and phonons in semiconductor and metallic quantum dots (QD). The simulations create an explicit timedomain representation of the excited-state processes, including elastic and inelastic electron-phonon scattering, multiple exciton generation, fission, and recombination. These nonequilibrium phenomena control the optical and electronic properties of QDs. Our approach can account for QD size and shape, as well as chemical details of QD structure, such as dopants, defects, core/shell regions, surface ligands, and unsaturated bonds. Each of these variations significantly alters the properties of photoexcited QDs.The insights reported in this review provide a comprehensive understanding of the excited-state dynamics in QDs and suggest new ways of controlling the photo-induced processes. The design principles that follow, guide development of photovoltaic cells, electronic and spintronic devices, biological labels, and other systems rooted in the unique physical and chemical properties of nanoscale materials.

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Isolation of the Magic‐Size CdSe Nanoclusters [(CdSe)₁₃(n‐octylamine)₁₃] and [(CdSe)₁₃(oleylamine)₁₃]

Cited by 135 publications

References 16 publications

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

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

Evolution of Self-Assembled ZnTe Magic-Sized Nanoclusters

Time-domain ab initio modeling of excitation dynamics in quantum dots

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