Customized Colloidal Quantum Dots

Introduction

Colloidal quantum dots (CQDs) are a class of nanoscale semiconductor particles synthesized and suspended in solution. From the early 1990s to the present, the synthesis of CQDs has improved in several ways: advances include organometallic synthesis in thermally coordinating solvents; thermal injection techniques; improved size control, size dispersion, and shape control; new materials emergence of systems; heterostructured particles such as core/shell CQDs and hybrid structures; synthesis via green chemistry; and increased control and understanding of nanoparticle surface chemistry. The abundant research progress has laid the foundation for expanding the application fields of CQDs materials.^[1]

Fig.1 Colloidal quantum dot device architectures^[2]

Our Services

Alfa Chemistry mainly prepares colloidal quantum dots in solution phase by chemical synthesis. Our synthetic route can be carried out under mild conditions and is not only green. It can also meet the needs of mass production. Alfa Chemistry is able to synthesize most colloidal quantum dots in the laboratory using batch reactors. Our synthetic routes include but are not limited to:

• Hot Injection Organometallic Synthesis

This type of synthesis method is to rapidly inject the pre-prepared precursor solution into a batch reactor filled with hot organic solvent, and obtain quantum dots of different sizes by controlling the reaction parameters such as the injection speed of the precursor, the stirring rate and the temperature.

Fig.2  (a) Schematic diagram for a hot-injection organometallic synthesis of QDs; (b) Schematic diagram for the synthesis of Ag2S QDs from a single source precursor of silver diethyldithiocarbamate.^[3]

• Non-injection organometallic synthesis

Alfa Chemistry's non-injection organometallic synthesis strategy mainly uses a one-pot method—introducing a nucleation initiator into the reaction system to automatically separate nucleation and growth. This non-injection method does not require precursor injection and can be easily scaled up to produce gram-scale high-quality colloidal quantum dots.

• Aqueous Synthesis

Using water, a "greener" solvent, to directly synthesize quantum dots in water. The hydration method is not only simple, mild, and low-cost, but also the surface functionalization of water-soluble ligands occurs during the synthesis process, which is suitable for biological applications. In addition, since the use of highly toxic organic reagents and high temperature reactions are avoided, it is more conducive to scale-up production.

Fig.3  (a) A schematic illustration of the synthesis of Cu:CdZnS/ZnS QDs; (b) A schematic illustration for the biosynthesis of CdS QDs.^[3]

• Biosynthesis

Alfa Chemistry enables the synthesis of quantum dots using the intrinsic enzymatic machinery of microorganisms. We mainly synthesize quantum dots by enzymes in the cytoplasm or cell membrane without the addition of chemical reaction precursors.

Service Process

References

1. Kim J Y, et al. 25th anniversary article: Colloidal quantum dot materials and devices: a quarter-century of advances. Advanced Materials. 2013, 25(36):4986-5010.
2. Cho J, et al. Janus colloid surfactant catalysts for in situ organic reactions in Pickering emulsion microreactors. Green Chemistry. 2018.
3. Pu Y, et al. Colloidal Synthesis of Semiconductor Quantum Dots toward Large-Scale Production: A Review. Industrial & Engineering Chemistry Research. 2018.

Click here to get in touch with us