Size-Dependent Absorption and Defect States in CdSe Nanocrystals in Various Multilayer Structures

2002 ◽  
Vol 2 (6) ◽  
pp. 645-652 ◽  
Author(s):  
D. Nesheva ◽  
Z. Levi ◽  
Z. Aneva ◽  
I. Zrinscak ◽  
C. Main ◽  
...  
Keyword(s):  
Multilayer Structures ◽  
Cdse Nanocrystals ◽  
Defect States ◽  
Size Dependent ◽  
Dependent Absorption

Quantum-Confined Electron Transitions in CdSe Nanocrystals

2000 ◽  
Vol 642 ◽  
Author(s):  
D. S. Ginger ◽  
A. S. Dhoot ◽  
C. E. Finlayson ◽  
N. C. Greenham
Keyword(s):  
Room Temperature ◽  
Electron State ◽  
Cdse Nanocrystals ◽  
Size Dependent ◽  
Excitonic Absorption ◽  
Electron Transitions ◽  
Delocalized Electron ◽  
Excitonic Transition ◽  
Dependent Absorption ◽  
Absorption Measurements

ABSTRACTWe present quasi-steady-state photoinduced absorption measurements on thin films of colloidal CdSe nanocrystals. We observe an intense, size-dependent absorption peaking in the mid-infrared when the samples are irradiated with visible light. The absorption is accompanied by a bleach in the visible near the position of the first excitonic absorption and persists with a lifetime of milliseconds at room temperature. We characterize the lifetime of the electron state and its cross-section. We attribute this feature to the 1S-1P transition of a delocalized electron. We report a bleaching of the first excitonic transition in electrically excited nanocrystal-based diode structures, and attribute it to charging of the 1S electron state.

Size dependent absorption kinetics of sedimenting nanoparticles

2013 ◽  
Author(s):  
Manoranjan Ghosh ◽  
Karabi Ghosh ◽  
Seema Shinde ◽  
S. C. Gadkari
Keyword(s):  
Absorption Kinetics ◽  
Size Dependent ◽  
Dependent Absorption ◽  
Kinetics Of

scholarly journals Aminophosphine Reduction Mechanisms and the Synthesis of Indium Phosphide Nanomaterials

2021 ◽  
Author(s):  
◽  
Geoffry Laufersky
Keyword(s):  
Indium Phosphide ◽  
Density Functional ◽  
Large Scale ◽  
Visible Spectrum ◽  
Size Dependent ◽  
Reduction Mechanisms ◽  
Highly Sensitive ◽  
Dependent Absorption ◽  
Entire Visible Spectrum ◽  
The Impact

<p>Indium phosphide (InP) nanomaterials are attractive for countless technological applications due to their well-placed band gap energies. The quantum confinement of these semiconductors can give rise to size-dependent absorption and emission features throughout the entire visible spectrum. Therefore, InP materials can be employed as low-toxicity fluorophores that can be implemented in high value avenues such as biological probes, lighting applications, and lasing technologies. However, large scale development of these quantum dots (QDs) has been stymied by the lack of affordable and safe phosphorus precursors. Syntheses have largely been restricted to the use of dangerous chemicals such as tris(trimethylsilyl)phosphine ((TMS)₃P), which is costly and highly sensitive to oxygen and water. Recently, less-hazardous tris(dialkylamino)phosphines have been introduced to produce InP QDs on par with those utilizing (TMS)₃P. However, a poor understanding of the reaction mechanics has resulted in difficulties tuning and optimizing this method.  In this work, density functional theory (DFT) is used to identify the mechanism of this aminophosphine precursor conversion. This understanding is then implemented to design an improved InP QD synthesis, allowing for the production of high-quality materials outside of glovebox conditions. Time is spent understanding the impact of different precursor salts on the reaction mechanisms and discerning their subsequent effects on nanoparticle size and quality. The motivation of this work is to formulate safer and less technical indium phosphide quantum dot syntheses to foster non-specialist and industrial implementation of these materials.</p>

Dependence of Tetrahedral Bond Lengths on the Surface Passivation and Stacking-Fault Density of CdSe Nanocrystals

2019 ◽  
Vol 57 ◽  
pp. 58-67
Author(s):  
Pin Jiun Wu ◽  
Yuri P. Stetsko ◽  
Meng Ting Hsieh
Keyword(s):  
Surface Passivation ◽  
Surface Effect ◽  
Stacking Faults ◽  
Expansion Ratio ◽  
Cdse Nanocrystals ◽  
Size Dependent ◽  
Dependent Behavior ◽  
Tetrahedral Bond ◽  
Organic Capping ◽  
Capping Ligands

We have investigated the surface effect of colloidally prepared CdSe nanocrystals (NCs) with the size range of 23-40 Å on their structural properties by changing the organic capping ligands. The TOPO/HDA-passivated NCs reveal a size-dependent behavior involving an elongated axial bondR(1)of an atomic tetrahedron and a shrunken equatorial bondsR(2). After treatment of the NCs with pyridine, the bond lengthR(1)decreases significantly whereasR(2)remains unchanged relative to the TOPO/HDA-passivated NCs, suggesting that a tensile stress along the [001] direction is contributed from the surface modification. In addition, we find that the expansion ratio of the pyridine-treated NCs along the c axis depends strongly on the density of stacking faults, which provides an evidence for the relaxation of atomic positions near the interface of stacking faults.

Sign in / Sign up

Export Citation Format

Share Document