Cadmium selenide
Names | |
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IUPAC name
Selanylidenecadmium[2]
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Other names | |
Identifiers | |
3D model (
JSmol ) |
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ChEBI | |
ChemSpider | |
ECHA InfoCard
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100.013.772 |
EC Number |
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13656 | |
MeSH | cadmium+selenide |
PubChem CID
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RTECS number
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UNII | |
UN number | 2570 |
CompTox Dashboard (EPA)
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Properties | |
CdSe | |
Molar mass | 191.385 g·mol−1 |
Appearance | Black, translucent, adamantine crystals |
Odor | Odorless |
Density | 5.81 g cm−3[3] |
Melting point | 1,240 °C (2,260 °F; 1,510 K)[3] |
Band gap | 1.74 eV, both for hex. and sphalerite[4] |
Refractive index (nD)
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2.5 |
Structure | |
Wurtzite
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C6v4-P63mc | |
Hexagonal | |
Hazards | |
GHS labelling: | |
Danger | |
H301, H312, H331, H373, H410 | |
P261, P273, P280, P301+P310, P311, P501 | |
NIOSH (US health exposure limits): | |
PEL (Permissible)
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[1910.1027] TWA 0.005 mg/m3 (as Cd)[5] |
REL (Recommended)
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Ca[5] |
IDLH (Immediate danger) |
Ca [9 mg/m3 (as Cd)][5] |
Related compounds | |
Other anions
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Cadmium oxide, Cadmium sulfide, Cadmium telluride |
Other cations
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Mercury(II) selenide
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Cadmium selenide is an
Structure
Three crystalline forms of CdSe are known which follow the structures of:
Production
The production of cadmium selenide has been carried out in two different ways. The preparation of bulk crystalline CdSe is done by the High-Pressure Vertical Bridgman method or High-Pressure Vertical Zone Melting.[8]
Cadmium selenide may also be produced in the form of
Production of cadmium selenide by arrested precipitation in solution is performed by introducing alkylcadmium and trioctylphosphine selenide (TOPSe) precursors into a heated solvent under controlled conditions.[11]
- Me2Cd + TOPSe → CdSe + (byproducts)
CdSe nanoparticles can be modified by production of two phase materials with ZnS coatings. The surfaces can be further modified, e.g. with mercaptoacetic acid, to confer solubility. [12]
Synthesis in structured environments refers to the production of cadmium selenide in
High temperature pyrolysis synthesis is usually carried out using an aerosol containing a mixture of volatile cadmium and selenium precursors. The precursor aerosol is then carried through a furnace with an inert gas, such as hydrogen, nitrogen, or argon. In the furnace the precursors react to form CdSe as well as several by-products.[9]
CdSe nanoparticles
CdSe-derived
CdSe quantum dots have been implemented in a wide range of applications including solar cells,
CdSe quantum dots are usually composed of a CdSe core and a ligand shell. Ligands play important roles in the stability and solubility of the nanoparticles. During synthesis, ligands stabilize growth to prevent aggregation and precipitation of the nanocrystals. These capping ligands also affect the quantum dot's electronic and optical properties by passivating surface electronic states.[19] An application that depends on the nature of the surface ligands is the synthesis of CdSe thin films.[20][21] The density of the ligands on the surface and the length of the ligand chain affect the separation between nanocrystal cores which in turn influence stacking and conductivity. Understanding the surface structure of CdSe quantum dots in order to investigate the structure's unique properties and for further functionalization for greater synthetic variety requires a rigorous description of the ligand exchange chemistry on the quantum dot surface.
A prevailing belief is that trioctylphosphine oxide (TOPO) or trioctylphosphine (TOP), a neutral ligand derived from a common precursor used in the synthesis of CdSe dots, caps the surface of CdSe quantum dots. However, results from recent studies challenge this model. Using NMR, quantum dots have been shown to be nonstoichiometric meaning that the cadmium to selenide ratio is not one to one. CdSe dots have excess cadmium cations on the surface that can form bonds with anionic species such as carboxylate chains.[22] The CdSe quantum dot would be charge unbalanced if TOPO or TOP were indeed the only type of ligand bound to the dot.
The CdSe ligand shell may contain both X type ligands which form
Applications
CdSe material is transparent to infra-red (IR) light and has seen limited use in photoresistors and in windows for instruments utilizing IR light. The material is also highly luminescent.[24] CdSe is a component of the pigment cadmium orange. CdSe can also serve as the n-type semiconductor layer in photovoltaic cells.[25]
Natural occurrence
CdSe occurs in the nature as the very rare mineral cadmoselite.[26][27]
Safety information
Cadmium is a toxic heavy metal and appropriate precautions should be taken when handling it and its compounds. Selenides are toxic in large amounts. Cadmium selenide is a known carcinogen to humans and medical attention should be sought if swallowed, dust inhaled, or if contact with skin or eyes occurs.[28][29]
References
- ^ a b "cadmium selenide (CHEBI:50834)". Chemical Entities of Biological Interest (ChEBI). UK: European Bioinformatics Institute. IUPAC Names.
- ^ "cadmium selenide – PubChem Public Chemical Database". The PubChem Project. USA: Nation Center for Biotechnology Information. Descriptors Computed from Structure.
- ^ ISBN 1-4398-5511-0.
- doi:10.1063/1.359815.
- ^ a b c NIOSH Pocket Guide to Chemical Hazards. "#0087". National Institute for Occupational Safety and Health (NIOSH).
- ISBN 3527306730.
- ISBN 0-8493-8912-7.
- ^ "II-VI compound crystal growth, HPVB & HPVZM basics". Archived from the original on 2005-09-15. Retrieved 2006-01-30.
- ^ PMID 16131177. Archived from the original(PDF) on 2017-09-21. Retrieved 2019-09-02.
- ^ PMID 22011091.
- .
- PMID 17387407.
- ^ Nanotechnology Structures – Quantum Confinement
- PMID 23306775.
- PMID 16478194.
- S2CID 4324973.
- PMID 9748158.
- PMID 9748157.
- .
- S2CID 135789570.
- .
- S2CID 2099893.
- .
- .
- ^ "Solar Energy". American Elements. Retrieved 12 April 2023.
- ^ "Cadmoselite".
- ^ "List of Minerals". 21 March 2011.
- ^ Additional safety information available at www.msdsonline.com, search 'cadmium selenide' (must register to use).
- ^ CdSe Material Safety Data Sheet Archived 2015-09-24 at the Wayback Machine. sttic.com.ru
External links
- Media related to Cadmium selenide at Wikimedia Commons
- National Pollutant Inventory – Cadmium and compounds
- Nanotechnology Structures – Quantum Confinement
- doi:10.1109/16.47767.
- T Ohtsuka; J Kawamata; Z Zhu; T Yao (1994). "p-type CdSe grown by molecular beam epitaxy using a nitrogen plasma source". Applied Physics Letters. 65 (4): 466. doi:10.1063/1.112338.
- Ma, C; Ding, Y; Moore, D; Wang, X; PMID 14733532.
- Califano, Marco; Zunger, Alex; Franceschetti, Alberto (2004). "Direct carrier multiplication due to inverse Auger scattering in CdSe quantum dots". Applied Physics Letters. 84 (13): 2409. .
- Schaller, Richard D.; Petruska, Melissa A.; Klimov, Victor I. (2005). "Effect of electronic structure on carrier multiplication efficiency: Comparative study of PbSe and CdSe nanocrystals". Applied Physics Letters. 87 (25): 253102. .
- Hendry, E.; Koeberg, M; Wang, F; Zhang, H; De Mello Donegá, C; Vanmaekelbergh, D; Bonn, M (2006). "Direct Observation of Electron-to-Hole Energy Transfer in CdSe Quantum Dots" (PDF). Physical Review Letters. 96 (5): 057408. PMID 16486988.*