What are CdSe quantum dots?

What are CdSe quantum dots?

CdSe quantum dots (QDs) are produced by simultaneously injecting cadmium (Cd) and selenium (Se) precursor solutions into a heated growth solution of octadecene in ambient atmosphere. Once combined, Se and Cd form CdSe clusters that become continually growing QDs as the reaction progresses.

How are quantum dots used in nanotechnology?

Quantum dots (QDs) are man-made nanoscale crystals that that can transport electrons. When UV light hits these semiconducting nanoparticles, they can emit light of various colors. For instance, due to their particular electronic properties they can be used as active materials in single-electron transistors.

Is CdSe toxic?

Results. In adult group, histological studies of testis tissues showed a high toxicity of CdSe: ZnS in 40 mg/kg dose followed by a decrease in lamina propria; destruction in interstitial tissue; deformation of seminiferous tubules; and a reduction in number of spermatogonia, spermatocytes, and spermatids.

Why ZnS is coated over CdSe?

An increase in the luminescence quantum yield and a red shift of the luminescence and absorption bands were observed as the CdSe cores became capped with ZnS. This red shift is explained (19) as leakage of the exciton into the ZnS shell, which increases the effective radius of the core.

Is CdSe ionic or covalent?

Cadmium selenide (CdSe) is a binary, primarily ionic compound with a touch of covalent character. It can take three crystalline forms, but the hexagonal wurtzite structure shown is by far the most common.

What is CdSe used for?

CdSe quantum dots have been implemented in a wide range of applications including solar cells, light emitting diodes, and biofluorescent tagging. CdSe-based materials also have potential uses in biomedical imaging.

What is the quantum dot used for?

Currently, quantum dots are used for labeling live biological material in vitro and in vivo in animals (other than humans) for research purposes – they can be injected into cells or attached to proteins in order to track, label or identify specific biomolecules.

What is quantum wire in nanotechnology?

From Wikipedia, the free encyclopedia. In mesoscopic physics, a quantum wire is an electrically conducting wire in which quantum effects influence the transport properties. Usually such effects appear in the dimension of nanometers, so they are also referred to as nanowires.

What is the band gap of CdSe quantum dots?

The UV- Vis absorbance peaks indicate the broad absorption behavior of the synthesized CdSe quantum dots. The calculated band gap energy was 2.55 eV and further it is found the particle size estimated from the maximum excitonic peaks for CdSe 2.7 nm.

Why the bandgap of bulk ZnS is larger than that of bulk CdS?

ZnS energy-gap is 3.54/3.91. For bulk crystals. If you mean cubic ZnCdS, then with increasing Zn contents the bandgap increases because ZnS has a larger bangap than CdS (3.8eV versus 2.55eV). We can understand this simply by using a linear interpolation between ZnS bandgap and CdS one.

What is CdSe in chemistry?

Cadmium selenide is an inorganic compound with the formula CdSe. It is a black to red-black solid that is classified as a II-VI semiconductor of the n-type. Much of the current research on this salt is focused on its nanoparticles.

What is the band gap of CdSe?

At room temperature the band gap of CdSe is 1.74 eV. 6 In the two-color scheme, photon energy of pump pulse is 3.10 eV, well above the band gap and is able to excite free electrons and holes at the surface of bulk CdSe crystal.

What are quantum dots (QDs)?

Two decades of research and investigation in the field of luminescent semiconductor nanoparticles, also known as quantum dots (QDs), have now passed since the fundamental work of Bawendi and co-workers, which focused particularly on the synthesis of II–VI materials [1–5].

Why radioactively labelled CdSe/CdS/ZnS QDs?

In order to aid in addressing those issues, CdSe/CdS/ZnS QDs were radioactively labelled, which allows quantification of the QD concentration in the whole body or in ex vivo samples by γ-counting.

How does the decay of 65Zn occur in CdSe QDs?

The decay of 65Zn occurs in the QDs and the influence of Cu in the coating layer of the QDs should be more fully investigated in terms of its lattice mismatch, self-purification and optical properties (e.g., dopant emission, PL enhancement or quenching). Experimental Synthesis of CdSe/CdS QDs

What is CdSe-based QD synthesis?

CdSe-based, state-of-the-art synthetic protocols typically use the hot injection method [1] and can deliver QDs with visible emission which possess quantum yields (QYs) of up to 85% as core/shell or alloyed structures [5–8].