Preparation of Quantum Dots-Alfa Chemistry

NEW YORK - Nov. 11, 2019 - PRLog -- In recent decades, quantum dots, also known as semiconductor nanocrystals, have become the focus of attention due to their unique electronic and luminescent properties and their applications in biomarkers, light-emitting diodes, lasers and solar cells. Compared to traditional organic dyes, quantum dots have excellent luminescence properties, such as adjustable fluorescence emission, narrow and symmetrical emission spectra, continuous absorption spectra, and light stability. At present, there are many methods for preparing quantum dots, including colloid method, chemical etching method, organometallic method, hydrothermal method and the like.

Colloid method

The colloidal method refers to a method in which an organic or inorganic substance of the metal solidifies is solidified in a solution or sol to form a quantum dot, which can be applied to the surface of the substrate by centrifugal force and annealed to form a desired nanocluster. This method attaches the colloid to the nanopore template. After annealing process in high temperature, the template is automatically removed, and the colloidal particles form crystals at high temperature. The size of the particles is related to the size of the template pores, the colloidal concentration and the annealing temperature.

Chemical etching method

Chemical etching method means that the quantum dot material is directly obtained by etching the crystal substrate. Due to the difference in the etching rate of the chemical liquid to different semiconductor materials and the anisotropy of the crystalline material, the pattern can be left on the crystal substrate by etching lithography to obtain nanometer-scale quantum dots.

Organometallic method

The organometallic method is the main method used to prepare quantum dots in organic systems. The organometallic method refers to a method for preparing quantum dots by pyrolysis of an organometallic precursor in an organic solvent of high boiling point. In this method, the organometallic precursor solution is injected into a ligand solution at 250℃ to 300 ℃, and the precursor is rapidly pyrolyzed under high temperature conditions to form a crystal nucleus which slowly grows into a nanocrystal. The precursors used in the ligand are mainly alkyl metals and alkyl non-metals (such as [Bis(trimethylsilyl)]selenide (https://www.alfa-chemistry.com/bis-trimethylsilyl-selenid...)) compounds. The advantage of this method is that a large number of quantum dots can be prepared and the yield of quantum dots is high.

Hydrothermal method

The hydrothermal method is a combination of inorganic synthesis and crystal preparation. In a closed reactor (such as a high pressure reactor), water is used as a reaction system for inorganic synthesis and material preparation by heating water to a supercritical temperature or near a supercritical temperature to generate a high pressure in the reaction system. Therefore, the hydrothermal method has become the main synthesis method for quantum dots (https://www.alfa-chemistry.com/products/quantum-dots-72.htm) directly used as bioluminescent probes.