Characteristics, Synthesis, and Applications of CdSe/ZnS Quantum Dots

CdSe/ZnS quantum dots are semiconductor nanoparticles composed of a cadmium selenide (CdSe) core and a zinc sulfide (ZnS) shell. The core-shell structure enhances the quantum dots' stability and fluorescence efficiency. CdSe provides excellent photoluminescence properties, while ZnS acts as a protective barrier, preventing the leakage of toxic Cd ions. These quantum dots exhibit unique optical and electronic properties due to quantum confinement effects, making them promising materials for a wide range of applications in various fields such as electronics, biotechnology, and medicine.

Characteristics of CdSe/ZnS Quantum Dots

• Optical Properties: CdSe/ZnS quantum dots exhibit tunable emission wavelengths based on their size, making them suitable for various imaging and sensing applications.
• High Quantum Yield: The ZnS shell improves the quantum yield of CdSe quantum dots, ensuring efficient light emission.
• Chemical Stability: The ZnS shell protects the CdSe core from oxidation and degradation, enhancing the overall stability of the quantum dots.
• Size-Dependent Properties: The optical and electronic characteristics of CdSe/ZnS quantum dots are heavily dependent on their size, offering versatility in various applications.

Synthesis of CdSe/ZnS Quantum Dots

The choice of synthesis method can influence the final quantum dot properties, such as quantum yield and emission wavelength. The synthesis of CdSe/ZnS quantum dots typically involves a two-step process: the formation of CdSe cores followed by the overcoating with a ZnS shell. Various methods such as hot injection, solvothermal synthesis, and microwave-assisted synthesis have been developed for the production of high-quality CdSe/ZnS quantum dots with precise control over size, shape, and optical properties.

In addition, successive ionic layer adsorption and reaction (SILAR) is one of the most widely used techniques for the synthesis of core/shell quantum dots. Junjie Hao et al. reported an improved tri-n-octylphosphine-assisted SILAR (TOP-SILAR) method that can form shells with precise thickness on quantum dot cores. The as-prepared thick-shell CdSe/ZnS quantum dots exhibit a high quantum yield (75%) and a narrow FWHM (26 nm).

TOP-SILAR for CdSe/ZnS quantum dots. [1]

CdSe/ZnS Quantum Dots from Alfa Chemistry

Catalog	Product Name
ACMA00017170	CdSe/ZnS Quantum Dots, Visible region, Organic solvent, 540nm
ACMA00017245	CdSe/ZnS Quantum Dots, Visible region, Organic solvent, 560nm
ACMA00017283	CdSe/ZnS Quantum Dots, Visible region, Organic solvent, 580nm
ACMA00017299	CdSe/ZnS Quantum Dots, Visible region, Organic solvent, 600nm
ACMA00017301	CdSe/ZnS Quantum Dots, Visible region, Organic solvent, 620nm
ACMA00017324	CdSe/ZnS Quantum Dots, Visible region, Organic solvent, 640nm
ACMA00017326	CdSe/ZnS Quantum Dots, Visible region, Organic solvent, 660nm
ACMA00017334	CdSe/ZnS Quantum Dots, Visible region, Organic solvent, 680nm
ACMA00017343	CdSe/ZnS Quantum Dots, Visible region, Water solvent, 540nm
ACMA00017345	CdSe/ZnS Quantum Dots, Visible region, Water solvent, 560nm
ACMA00017358	CdSe/ZnS Quantum Dots, Visible region, Water solvent, 580nm
ACMA00017373	CdSe/ZnS Quantum Dots, Visible region, Water solvent, 600nm
ACMA00017379	CdSe/ZnS Quantum Dots, Visible region, Water solvent, 620nm
ACMA00017398	CdSe/ZnS Quantum Dots, Visible region, Water solvent, 640nm
ACMA00017408	CdSe/ZnS Quantum Dots, Visible region, Water solvent, 660nm
ACMA00017416	CdSe/ZnS Quantum Dots, Visible region, Water solvent, 680nm

Functionalization of CdSe/ZnS Quantum Dots

Functionalization of CdSe/ZnS quantum dots involves the attachment of organic ligands, biomolecules, or polymers onto the nanoparticle surface. This process imparts additional functionalities, improves stability, enables biocompatibility, and facilitates targeted interactions with specific molecules or environments.

Alfa Chemistry can provide a range of functionalized CdSe/ZnS quantum dots to meet your specific needs.

Catalog	Product Name
ACMA00016837	CdSe/ZnS quantum dots, amine functionalized, fluorescence: λem 540nm
ACMA00016838	CdSe/ZnS quantum dots, amine functionalized, fluorescence: λem 560nm
ACMA00016846	CdSe/ZnS quantum dots, amine functionalized, fluorescence: λem 580nm
ACMA00016852	CdSe/ZnS quantum dots, amine functionalized, fluorescence: λem 600nm
ACMA00016861	CdSe/ZnS quantum dots, amine functionalized, fluorescence: λem 620nm
ACMA00016862	CdSe/ZnS quantum dots, amine functionalized, fluorescence: λem 645nm
ACMA00016887	CdSe/ZnS quantum dots, carboxylic acid functionalized, fluorescence: λem 520nm
ACMA00016899	CdSe/ZnS quantum dots, carboxylic acid functionalized, fluorescence: λem 560nm, 1 mg/mL in H2O
ACMA00016901	CdSe/ZnS quantum dots, carboxylic acid functionalized, fluorescence: λem 580nm
ACMA00016914	CdSe/ZnS quantum dots, carboxylic acid functionalized, fluorescence: λem 645nm
ACMA00016920	CdSe/ZnS quantum dots, carboxylic acid, fluorescence: λem 600nm
ACMA00016945	CdSe/ZnS quantum dots, PEG functionalized, fluorescence: λem 520nm
ACMA00016965	CdSe/ZnS quantum dots, PEG functionalized, fluorescence: λem 580nm
ACMA00016980	CdSe/ZnS quantum dots, PEG functionalized, fluorescence: λem 620nm
ACMA00016989	CdSe/ZnS quantum dots, stabilized with octadecylamine ligands, fluorescence: λem 540nm, 5 mg/mL in toluene
ACMA00017008	CdSe/ZnS quantum dots, stabilized with octadecylamine ligands, fluorescence: λem 560nm, 5 mg/mL in toluene
ACMA00017039	CdSe/ZnS quantum dots, stabilized with octadecylamine ligands, fluorescence: λem 580nm, 5 mg/mL in toluene
ACMA00017107	CdSe/ZnS quantum dots, stabilized with octadecylamine ligands, fluorescence: λem 600nm, 5 mg/mL in toluene
ACMA00017131	CdSe/ZnS quantum dots, stabilized with octadecylamine ligands, fluorescence: λem 620nm, 5 mg/mL in toluene
ACMA00017164	CdSe/ZnS quantum dots, stabilized with octadecylamine ligands, fluorescence: λem 645nm, 5 mg/mL in toluene

Applications of CdSe/ZnS Quantum Dots

• Biological Imaging

CdSe/ZnS quantum dots have found extensive use in bioimaging due to their bright and photostable fluorescence, enabling long-term tracking of biological processes. Pedro J. Pacheco-Liñán et al. used d-penicillamine and small peptides to functionalize CdSe/ZnS quantum dots to obtain pH probes that can be used in fluorescence lifetime imaging microscope (FLIM). These CdSe/ZnS QDs-based fluorescent probes can be used to measure intracellular pH in live cells.

CdSe/ZnS QDs-based pH probes for FLIM. [2]

• Sensing and Detection

The high sensitivity and tunable emission of CdSe/ZnS quantum dots make them valuable for sensor development in areas such as environmental monitoring and medical diagnostics.

• Light-Emitting Devices

These quantum dots are utilized in the production of LED displays and lighting due to their color purity and brightness. Xiangtian Xiao et al. used CdSe/ZnS core/shell QDs and related luminescent microspheres (LMS) as light conversion materials to prepare QD-LED and QD-WLED with wide modulation bandwidths reaching 74.19% and 67.75%.

CdSe/ZnS QDs based- LEDs. [3]

• Solar Cells

CdSe/ZnS quantum dots are explored for enhancing the efficiency of photovoltaic devices through their light-harvesting capabilities and electron transport properties.

References

1. Hao, Junjie, et al. Scientific Reports, 2019, 9(1), 12048.
2. Pacheco-Liñán, Pedro J., et al. ACS sensors, 2020, 5(7), 2106-2117.
3. Xiao, Xiangtian, et al. Optics Express, 2016, 24(19), 21577-21586.

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