A Deep Dive into InP/ZnS Quantum Dots from Synthesis to Applications

InP/ZnS quantum dots are semiconductor nanoparticles composed of an indium phosphide (InP) core surrounded by a zinc sulfide (ZnS) shell. These nanocrystals exhibit unique optical and electronic properties due to their small size and quantum confinement effects. They are widely used in various scientific and industrial applications, including bioimaging, photovoltaics, and light-emitting diodes.

Characteristics of InP/ZnS Quantum Dots

InP/ZnS quantum dots possess several key characteristics that make them attractive for a range of applications.

• They exhibit size-dependent emission properties, with tunable emission wavelengths ranging from the visible to the near-infrared spectrum.
• InP/ZnS quantum dots have high photoluminescence quantum yields, making them efficient light-emitting materials.
• The core-shell structure offers enhanced chemical and photo-stability and reduces the impact of surface defects.
• They also demonstrate excellent colloidal stability and biocompatibility, further enhancing their potential for use in biological imaging and sensing applications.
• These quantum dots possess a high molar extinction coefficient, making them ideal for applications in biological imaging, light-emitting diodes (LEDs), and photovoltaic devices.

InP/ZnS Quantum Dots from Alfa Chemistry

Catalog	Product Name
ACM22398807-36	InP/ZnS Quantum Dots, Purity = 99.9%, λex = 520nm
ACM22398807-37	InP/ZnS Quantum Dots, Purity = 99.9%, λex = 550nm
ACM22398807-38	InP/ZnS Quantum Dots, Purity = 99.9%, λex = 580nm
ACM22398807-39	InP/ZnS Quantum Dots, Purity = 99.9%, λex = 610nm
ACM22398807-40	InP/ZnS Quantum Dots, Purity = 99.9%, λex = 640nm
ACM22398807-41	InP/ZnS Quantum Dots, Purity = 99.9%, λex = 660nm
ACM22398807-42	InP/ZnS Quantum Dots, Purity = 99.9%, λex = 690nm
ACM22398807-43	InP/ZnS Quantum Dots, Purity = 99.9%, λex = 720nm
ACM22398807-44	InP/ZnS Quantum Dots, Purity = 99.9%, λex = 750nm
ACMA00022623	InP/ZnS quantum dots, fluorescence: λem 530nm, 5 mg/mL in toluene
ACMA00022624	InP/ZnS quantum dots, fluorescence: λem 560nm, 5 mg/mL in toluene
ACMA00022625	InP/ZnS quantum dots, fluorescence: λem 620nm, 5 mg/mL in toluene
ACMA00022626	InP/ZnS quantum dots, fluorescence: λem 650nm, 5 mg/mL in toluene
ACMA00022627	InP/ZnS quantum dots, stabilized with oleylamine ligands, fluorescence: λem 590nm, 5 mg/mL in toluene

Synthesis Methods of InP/ZnS Quantum Dots

The synthesis of InP/ZnS quantum dots involves a multi-step process that typically begins with the preparation of the InP core nanoparticle followed by the growth of the ZnS shell.

• Synthesis of InP Crystals

Schematic of QD synthesis by hot-injection. [1]

• Direct Synthesis: Direct synthesis of InP QDs involves the reaction of [In] and [P] precursors in a common solution typically consisting of a high-boiling organic solvent and coordinating capping ligands. There are two types of bench-top techniques available for the controlled synthesis of nanocrystals, namely hot injection and heating.
• Seed-Templated Synthesis: The formation of InP QDs was mediated by using preformed seed nanoparticles as templates, including seed growth and cation exchange methods.
• Scalable Synthesis: To enable large-scale fabrication of InP quantum dots, microwave-assisted synthesis and microfluidic technologies that allow large reaction vessels or continuous synthesis are developed as potential technologies for large-scale production.

• Shell Passivation with ZnS

To further eliminate the trapping of electrons and holes, it is necessary to passivate the anionic and cationic surface sites by embedding InP QDs in another semiconductor material to form core-shell QDs. Zinc blende (ZnS) is the most commonly used shell material to passivate various quantum dots and can be coated on the surface of InP core nanoparticles through methods such as continuous ion layer adsorption and reaction (SILAR).

Applications of InP/ZnS Quantum Dots

• Bioimaging and Bioassays

InP/ZnS quantum dots are used as fluorescent probes for cellular and molecular imaging, enabling real-time visualization of biological processes at the nanoscale level. Zahra Ranjbar-Navazi et al. functionalized the synthesized InP/ZnS quantum dots (QDs) with folic acid (FA) and D-glucosamine (GA), and further conjugated it with doxorubicin to obtain QD-FA-GA-DOX, which can be used as a theranostics for simultaneous imaging and therapy of cancer.

Functionalized InP/ZnS quantum dots. [2]

• Optoelectronic Devices

The unique optical properties of InP/ZnS quantum dots make them promising candidates for optoelectronic devices. They are utilized in the fabrication of high-performance LEDs, displaying enhanced color purity and brightness. Furthermore, the quantum dots' efficient charge carrier dynamics make them suitable for next-generation photodetectors, solar cells, and displays, offering improved energy conversion efficiencies and device performance.

• Photocatalysis

InP/ZnS quantum dots have the potential to be used as photocatalysts for various reactions, such as redox and carbon-carbon coupling reactions. Indra Narayan Chakraborty et al. demonstrated that InP/ZnS QDs can photocatalyze ferricyanide reduction in the presence of sacrificial agents with high photoconversion yield and recyclability. More striking is the ability of InP/ZnS QDs to specifically photocatalyze the C–C coupling reaction between 1-phenylpyrrolidine and phenyl trans styryl sulfone without the help of any cocatalyst or sacrificial reagent.

InP/ZnS QDs for photocatalysis. [3]

References

1. Chen B, et al. Small, 2020, 16(32), 2002454.
2. Ranjbar-Navazi Z, et al. Journal of drug targeting, 2018, 26(3), 267-277.
3. Chakraborty I N, et al. Chemistry of Materials, 2019, 31(7), 2258-2262.

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