Colloidal quantum dots

are tiny particles, or “nanoparticles”, of a semiconductor material, traditionally chalcogenides (selenides or sulfides) of metals like cadmium or zinc (CdSe or ZnS, for example), which range from 2 to 10 nanometers in diameter (about the width of 50 atoms).  Because of their small size, quantum dots display unique optical and electrical properties that are different in character to those of the corresponding bulk material.  The most immediately apparent of these is the emission of photons under excitation, which are visible to the human eye as light.  Moreover, the wavelength of these photon emissions depends not on the material from which the quantum dot is made, but its size.

The ability to precisely control the size of a quantum dot enables us to determine the wavelength of the emission, which in turn determines the color of light the human eye perceives.  Quantum dots can therefore be “tuned” during production to emit any color of light desired.  The ability to control, or “tune” the emission from the quantum dot by changing its core size is called the “size quantization effect”.  The smaller the dot, the closer it is to the blue end of the spectrum, and the larger the dot, the closer to the red end. Dots can even be tuned beyond visible light, into the infra-red or into the ultra-violet.

Quantum Dots have a substantial advantages over conventional organic dyes: (1) different colored dots with narrow emission spectra can be excited with a single wavelength making multicolor imaging easier, and (2) emission is 10-20 times stronger and much more photostable, making single molecule imaging routinely practical.  Despite their potential, few applications for semiconductor nanocrystals have been fully developed, in large part due to the difficulty and cost associated with producing uniform nanosize particles in sufficient quantities.

Potential applications of semiconductor nanoparticles include light emitting diodes, displays, biological fluorescent labels, solar cells, lasers, and catalysts.  Cadmium selenide is the most studied material, arguably due to its tunable fluorescence in the visible region and potential use in industrial and biomedical applications.

Now, the ability to mass-produce consistently high quality quantum dots enables product designers to envisage their use in consumer products and a wide range of other applications for the first time, and then bring these superior, next-generation products to market.  Together with our partners, this is what Irilliant does.