Preparation of Quantum Dots with High Purity and High Emission Quantum Efficiency
Quantum dots (QDs) are fluorescent semiconductor nanocrystals that have unique optical and electronic properties. QDs have high photoluminescent (PL) quantum yields with size tunable emission wavelength, superior brightness, high resistance to photobleaching, and simultaneous excitation of multiple colors from a single light source. These properties make QDs a unique class of light emitting nanocrystals that find promising potential applications in various fields.
Ocean NanoTech offers a complete line of core and core-shell quantum dot powder, colloidal dispersion in organic solvent, and colloidal dispersion in aqueous solution. Ocean’s quantum dots can be used for photovoltaic cells, light emitting diodes (LEDs), telecommunication and diode lasers. Ocean’s quantum dots are also used in the life sciences and medical diagnostics for drug delivery, cell imaging, labeling of biomolecules, etc.
Ocean NanoTech has transcended the challenges in the bulk preparation of high quality quantum dots through two recent revolutionary process breakthroughs. The first breakthrough involves the change of precursors from organometallic dimethylcadmium and dimethylzinc to inorganic materials such as cadmium oxide, cadmium acetate, and zinc oxide as well as a change from the sulfur precursor, hexamethylsilylathiane, to elemental sulfur. The second breakthrough involves the shell layer crystallization growth controlled by a layer-by-layer procedure where the cationic and anionic layers grow alternately through separate injections. In this process, the amount of cationic or anionic layers are controlled to a monolayer scale for each injection where free cation or anion in the reaction system can be kept at the minimum amount before the injection of the oppositely charged ion. These improvements produce quantum dots core/shell nanocrystals that have >70% quantum yield at the emission wavelength range of 500-630 nm.
High quality quantum dots with the emission wavelength peak range at 580-630 nm that are highly suitable for optoelectronic applications such as solar cells and QDLEDs (Quantum Dot Based Light-Emitting Diodes) are also available at Ocean NanoTech. The quantum yield of these nanocrystals is > 40%. With the support of federal agencies like the NSF, NIH and DOD, and our academic partners, we have prepared and demonstrated our high quality quantum dot powders at electronic grade have excellent electroluminescent efficiency for the fabrication of LED devices. For more information about our research in QDLEDs please click here. Additional information about our CdSe/ZnS quantum dot powder products are found here.