Wurtzite or zinc blende? Surface decides the crystal structure of nanocrystals

Soni, Udit; Arora, Vikas; Sapra, Sameer

doi:10.1039/c3ce40267c

Cited by 46 publications

(38 citation statements)

References 24 publications

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“…2a, 0.348 nm of interplanar spacing was derived for the CdSe core QDs, which is in good agreement with the crystal lattice plane (111) of bulk cubic zinc blende (ZB) CdSe (d 111 = 0.351 nm for ZB CdSe, JCPDS No. 00-019-0191) 31–34 . As shown in the HRTEM image of CdSe/ZnS(7) TSQDs (inset in Fig.…”

Section: Resultsmentioning

confidence: 99%

A facile route to synthesize CdSe/ZnS thick-shell quantum dots with precisely controlled green emission properties: towards QDs based LED applications

Hao

Liu

Miao³

et al. 2019

Sci Rep

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In recent, the quantum yield (QY) and stability of green quantum dots (QDs) have been significantly improved. However, most of the progresses were achieved by using alloyed QDs, and the control of green emission QDs still remains challenging. Herein, we report a novel method for synthesizing thick-shell structure quantum dots (TSQDs) with saturated green-emitting where tri-n-octylphosphine (TOP) was used as both ligand and solvent to extract the redundant ions from the QDs surface and remove the lattice imperfections before any surface inorganic layer-by-layer coating. The as-prepared TSQDs demonstrate enhanced luminescent properties including high QY reaching up to 75%, full width at half maximum (FWHM) remaining close to 26 nm and tunable precise emission properties (532 nm), which can be utilized to perform 91% of the International Telecommunication Union (ITU) Recommendation BT. 2020 (Rec. 2020) for high definition and color gamut displays.

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Section: Resultsmentioning

confidence: 99%

A facile route to synthesize CdSe/ZnS thick-shell quantum dots with precisely controlled green emission properties: towards QDs based LED applications

Hao

Liu

Miao³

et al. 2019

Sci Rep

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“…From figure 1(a) (inset) the inter-planer distance d is calculated to be 0.34 nm corresponding to 002 plane of graphitic carbon [15]. Similar calculation from SAED pattern of figure 1(b) (inset) gives value of 0.22 nm corresponding to 220 plane of CdSe QD [16] .…”

Section: Resultsmentioning

confidence: 65%

Exploring dynamics of resonance energy transfer in hybrid Quantum Dot Sensitized Solar Cells (QDSSC)

Ramanarayanan

Ummer

Sindhu

2020

Mater. Res. Express

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Graphene based nanomaterials are known to provide new avenues to improve semiconductor based light harvesting devices. This work makes use of graphene quantum dots (GQD) to improve the efficiency of a CdSe Quantum Dot Sensitized Solar Cell (QDSSC) by Förster Resonance Energy Transfer (FRET) mechanism. FRET describes non-radiative energy transfer between two adjacent molecules typically in range from 1 to 10 nm with one molecule as donor and other molecule as acceptor. If the acceptor is in close proximity of the excited donor, then their dipoles align resulting in transfer of excitation energy from donor to acceptor. Here graphene quantum dot acts as the energy donor to enhance light harvesting of CdSe quantum dot which acts as an acceptor in the hybrid solar cell. The introduction of GQD increases the efficiency of CdSe sensitized QDSSC from 0.18 to 0.28% showing an efficiency enhancement of 55%. The improved efficiency is mainly attributed to the 46% increase in current density of the GQD-CdSe solar cell compared to the CdSe QDSSC. The increased performance of the QDSSC owes to the existence of non-radiative energy transfer (FRET) between GQD and CdSe evident from photoluminescence (PL) quenching and lifetime measurements. This FRET system of GQD (donor)-CdSe (acceptor) shows an energy transfer of 48.7% providing new insights for selective light harvesting of the solar spectrum which can be utilised for various potential applications in future.

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“…For small-diameter QDs, the XRD peaks are broad and their intensity decreases with decreasing QD size. The diffraction peaks are determined to correspond to the (111), (220), and (311) planes of the zinc blende CdSe crystalline phase, and an additional peak corresponding to the (400) plane is confirmed at a diffraction angle of 2θ = 62 • [18]. The three main distinguished XRD peaks include one peak at a diffraction angle of 2θ = 25 • attributed to the (111) crystal facet and two broad peaks at 2θ = 42 • and 50 • corresponding to the (220) and (311) planes.…”

Section: Resultsmentioning

confidence: 95%

Influence of Size and Shape Anisotropy on Optical Properties of CdSe Quantum Dots

et al. 2020

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We used low-temperature reactions to synthesize different-sized CdSe quantum dots (QDs) capped with fatty-acid and phosphine ligands. From the correlation of high-resolution transmission electron microscopy and X-ray diffraction (XRD) analyses of the synthesized QDs, we observed size-dependent shape anisotropy. In addition, the recorded XRD patterns revealed mixed crystal facets with zinc blende and wurtzite structures in small-sized QDs. Furthermore, from differential absorption (DA) spectra, we extracted the electronic transition energies for different-sized QDs, which were found to be similar to the calculated values of the quantum size levels associated with band mixing of CdSe QDs with a moderate bandgap. We found that the excitonic absorption peaks are increasingly “hidden” with decreasing QD size because of the crystal structure and crystalline quality. The results show good agreement with the obtained diffraction patterns and the estimation errors obtained from the DA spectra.

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Wurtzite or zinc blende? Surface decides the crystal structure of nanocrystals

Cited by 46 publications

References 24 publications

A facile route to synthesize CdSe/ZnS thick-shell quantum dots with precisely controlled green emission properties: towards QDs based LED applications

A facile route to synthesize CdSe/ZnS thick-shell quantum dots with precisely controlled green emission properties: towards QDs based LED applications

Exploring dynamics of resonance energy transfer in hybrid Quantum Dot Sensitized Solar Cells (QDSSC)

Influence of Size and Shape Anisotropy on Optical Properties of CdSe Quantum Dots

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