The Enhancement of Band Edge Emission from ZnS/Zn(OH)2 Quantum Dots

2000 ◽  
Vol 642 ◽  
Author(s):  
Hatim Mohamed El-Khair ◽  
Ling Xu ◽  
Xinfan Huang ◽  
Minghai Li ◽  
Xiaofeng Gu ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Surface Passivation ◽  
Band Edge ◽  
Band Edge Emission ◽  
Trap States ◽  
Edge Emission ◽  
Surface Trap ◽  
Quantum Size ◽  
Transmission Electron

ABSTRACTWurtzite structure monodisperse ZnS quantum dots (QDs) of 1 to 5 nm diameter, synthesized by colloidal chemical method, were confirmed by transmission electron microscopy (TEM) images and electron diffraction (ED) patterns. Enhanced blue shifted band edge emission from Zn(OH)2 capped ZnS QDs with decreasing size has been observed, which indicates the role of inorganic surface passivation and hence supports the quantum size effect. Detectable far-red shifted emission from bare ZnS QDs has been observed when QDs precursors and stabilizer dispersed in solvents with different polarities. This emission is attributed to the surface trap states of different energies.

Enhancement of Photoluminescence from Organic and Inorganic Surface Passivated ZnS Quantum Dots

2001 ◽  
Vol 667 ◽  
Author(s):  
Hatim Mohamed El-Khair ◽  
Ling Xu ◽  
Mingha Li ◽  
Yi Ma ◽  
Xinfan Huang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Organic Coating ◽  
Band Edge ◽  
Band Edge Emission ◽  
Trap States ◽  
Edge Enhancement ◽  
Edge Emission ◽  
Inorganic And Organic

ABSTRACTZnS quantum dots (QDs) chemically synthesized in PVP stabilizing medium have been coated with Zn(OH)2, SiO2and polystyrene (PS) shells as inorganic and organic passivation agents. to synthesize ZnS/Zn(OH)2, ZnS/SiO2and ZnS/PS QDs. PL properties of inorganically passivated ZnS/Zn(OH)2 and ZnS/SiO2 had reported band edge enhancement of 8-10 times, while organically passivated ZnS/PS QDs exhibit tremendous enhancement of band edge emission as much as 10-15 times,. Therefore inorganic and organic coating can passivate trap states of different energies on the surface of ZnS QDs.

scholarly journals Plasmon-Assisted Suppression of Surface Trap States and Enhanced Band-Edge Emission in a Bare CdTe Quantum Dot

2019 ◽  
Vol 10 (11) ◽  
pp. 2874-2878 ◽  
Author(s):  
Assegid Mengistu Flatae ◽  
Francesco Tantussi ◽  
Gabriele C. Messina ◽  
Francesco De Angelis ◽  
Mario Agio
Keyword(s):  
Quantum Dot ◽  
Band Edge ◽  
Band Edge Emission ◽  
Trap States ◽  
Edge Emission ◽  
Surface Trap ◽  
Cdte Quantum Dot

Disentangling the role of linear transition dipole in band-edge emission from single CdSe/ZnS quantum dots: Combined linear anisotropy and defocused emission pattern imaging

2010 ◽  
Vol 97 (12) ◽  
pp. 121915 ◽  
Author(s):  
Austin Cyphersmith ◽  
Kevin Early ◽  
Artem Maksov ◽  
Jeremy Graham ◽  
Yikuan Wang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Band Edge ◽  
Band Edge Emission ◽  
Edge Emission ◽  
Transition Dipole ◽  
Emission Pattern

scholarly journals Core Nanoparticle Engineering for Narrower and More Intense Band-Edge Emission from AgInS2/GaSx Core/Shell Quantum Dots

Nanomaterials ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1763 ◽  
Author(s):  
Watcharaporn Hoisang ◽  
Taro Uematsu ◽  
Takahisa Yamamoto ◽  
Tsukasa Torimoto ◽  
Susumu Kuwabata
Keyword(s):  
Surface Passivation ◽  
Precursor Solution ◽  
Silver Sulfide ◽  
Band Edge ◽  
Crystal Phase ◽  
Band Edge Emission ◽  
Edge Emission ◽  
Orthorhombic Crystal ◽  
Metal Precursor ◽  
Ag2s Nanoparticles

Highly luminescent silver indium sulfide (AgInS2) nanoparticles were synthesized by dropwise injection of a sulfur precursor solution into a cationic metal precursor solution. The two-step reaction including the formation of silver sulfide (Ag2S) nanoparticles as an intermediate and their conversion to AgInS2 nanoparticles, occurred during the dropwise injection. The crystal structure of the AgInS2 nanoparticles differed according to the temperature of the metal precursor solution. Specifically, the tetragonal crystal phase was obtained at 140 °C, and the orthorhombic crystal phase was obtained at 180 °C. Furthermore, when the AgInS2 nanoparticles were coated with a gallium sulfide (GaSx) shell, the nanoparticles with both crystal phases emitted a spectrally narrow luminescence, which originated from the band-edge transition of AgInS2. Tetragonal AgInS2 exhibited narrower band-edge emission (full width at half maximum, FWHM = 32.2 nm) and higher photoluminescence (PL) quantum yield (QY) (49.2%) than those of the orthorhombic AgInS2 nanoparticles (FWHM = 37.8 nm, QY = 33.3%). Additional surface passivation by alkylphosphine resulted in higher PL QY (72.3%) with a narrow spectral shape.

Removal of Surface States and Recovery of Band-Edge Emission in InAs Nanowires through Surface Passivation

Nano Letters ◽  
2012 ◽  
Vol 12 (7) ◽  
pp. 3378-3384 ◽  
Author(s):  
M. H. Sun ◽  
H. J. Joyce ◽  
Q. Gao ◽  
H. H. Tan ◽  
C. Jagadish ◽  
...  
Keyword(s):  
Surface Passivation ◽  
Surface States ◽  
Band Edge ◽  
Band Edge Emission ◽  
Edge Emission ◽  
Inas Nanowires

Enhancement of Band Edge Emission from ZnS/Zn(OH) 2 Quantum Dots

2001 ◽  
Vol 18 (4) ◽  
pp. 616-618 ◽  
Author(s):  
Hatim Mohamed El-Khair ◽  
Xu Ling ◽  
Huang Xin-Fan ◽  
Li Ming-Hai ◽  
Chen Kun-Ji
Keyword(s):  
Quantum Dots ◽  
Band Edge ◽  
Band Edge Emission ◽  
Edge Emission

Nonlinear Optical Properties of Cds-SiO2 Glass Composite Thin Films Prepared by RF-Sputtering

1991 ◽  
Vol 244 ◽  
Author(s):  
I. Tanahashi ◽  
M. Yoshida ◽  
Y. Manabe ◽  
T. Mitsuyu ◽  
T. Tokizaki ◽  
...  
Keyword(s):  
Rf Sputtering ◽  
Blue Shift ◽  
Band Edge ◽  
Nonlinear Susceptibility ◽  
Near Band Edge ◽  
Band Edge Emission ◽  
Edge Emission ◽  
Third Order ◽  
Quantum Size ◽  
Third Order Nonlinear Susceptibility

ABSTRACTCdS-microcrystallites-embedded films of SiO2 were successfully prepared by rf-sputtering. The optical absorption edge of the film with 18.5 at% CdS clearly exhibited a blue shift by 0.13 eV compared to bulk CdS, indicating the quantum size effect due to confinement of electrons and holes in CdS microcrystallites. The blue-shift decreased with increasing the CdS concentration. The photoluminescence spectra of the films also exhibited the blue shift in band-edge emission. From decay curves of the band-edge emission, the dominant decay time was estimated to be 100 ps, and longer components were weak. Optical nonlinear susceptibility of the films was measured by degenerated four-wave mixing experiments near band-edge. The third-order nonlinear susceptibility was estimated to be 5.0 × 10−7 esu at 77K for the film with 46.3 at% of CdS.

Role of Cation-Anion Organic Ligands for Optical Properties of Fully Inorganic Perovskite Quantum Dots

MRS Advances ◽  
2018 ◽  
Vol 3 (55) ◽  
pp. 3255-3261 ◽  
Author(s):  
Aaron Forde ◽  
Talgat Inerbaev ◽  
Dmitri Kilin
Keyword(s):  
Quantum Dots ◽  
Surface Passivation ◽  
Binding Energies ◽  
Organic Ligands ◽  
Trap States ◽  
Light Emitting ◽  
Inorganic Perovskite ◽  
Perovskite Quantum Dots ◽  
Reasonable Choice

ABSTRACTApplication of lead-halide perovskite nanostructures for photovoltaic and light emitting applications depends on fashion of the surface termination. The reasonable choice of surface ligands for perovskite nanostructures prevent formation of trap states and contribute to chemical stability, wide opening of the bandgap, and intensity of absorption and photoluminescence of perovskite nanostructures. This work provides atomistic arguments for dual ligand protocol of surface passivation of fully inorganic perovskite quantum dots with fully organic ligands being a mix of cations (ethyl-ammonium) and anions (acetic) in nearly equal proportions. Computed binding energies of either individual ligands or anion-cation pairs demonstrate high stability in comparison to thermal energy and are concluded to be favourable choice in synthesis of colloidal perovskite quantum dots for light emitting applications.

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