In The News

Posted by: Kenneth Werner

Thursday, December 12, 2013

Supply Chain - Quantum Materials is the new quantum dot company in town. It needs to play catch-up with the established players, but it is offering something different.

The two established players — QD Vision of Lexington, Massachusetts and Nanosys Inc. of Milpitas, California — dominate the consciousness of those who spend time thinking about the application of quantum dots (QDs) to electronic displays. QD Vision currently incorporates its QDs in an optical component it calls Color IQ, which sits in front of the LEDs in an LED edge-light. The component is being used in several models of Sony Bravia TV sets.

Nanosys has partnered with 3M’s Optical Systems Division, which is applying Nanosys QDs to a polymer film and passivating it with a 3M moisture blocking film. 3M calls the finished product Quantum Dot Enhancement Film (QDEF). In contrast to QD Vision’s Color IQ, QDEF is applied parallel to the entire surface of an LCD. Indeed, it substitutes for the diffusing film in the LCD’s backlight.

It is probably not necessary to remind Display Daily’s knowledgeable audience that QDs absorb photons of light and re-emit the energy at longer wavelengths with a very narrow emission spectrum. The specific color emitted depends on the size of the QD’s core, which ranges from roughly 2.0 to 4.2 nanometers for the visible spectrum.

For all of their differences, the QDs made by both companies have two things in common: They are roughly spherical, and they are made with a colloidal batch process.

And that’s where Quantum Materials Corp. (QMC) enters the story. With technology based on Rice University patents, QMC is producing QDs that have a tetrapod-like, rather than spherical, geometry. In a conference call yesterday, R&D VP David Doderer told me that tetrapods have a variety of advantages in different applications. For displays, there is a degree of self-assembly when the tetrapods are deposited on a substrate, which produces a layer in which the QDs are separated from each other by their appendages, which avoids the use of excessive material and also avoids quenching of the re-emission, resulting in better efficiency. Also, the emission spectrum has a width that, at 20nm full width at half maximum (FWHM), is roughly half that of spherical QDs, Doderer said.

Although, in other applications, the core and the appendages can be separately engineered to produce different wavelengths of light, a single narrow wavelength is selected for displays.

QMC’s competitors produce their QDs in a colloidal batch process, which means that the chemical precursors are mixed together and heated in a container until the temperature is reached at which the precursors are converted into the QDs. The approach is effective but slow, said Doderer, and would probably not supply enough material to support large-scale TV manufacturing. (In fairness, we should mention at this point that Nanosys announced in early October that they had cumulatively produced 2000 kg of QDs,. which is a goodly amount.)

QMC has patented a continuous manufacturing approach using a microfluidic reactor. One small reactor can produce 100 kg of tetrapod QDs per day, or 30,000 kg per year. If you want more, add reactors. And the tetrapodal QDs made by the Rice University method is extremely uniform, with 90% of the QDs having a full tetrapodal shape, and more than 90% emission uniformity.

QMC got a later start than its competitors. QD Vision is already in a shipping product, and 3M’s QDEF is being manufactured in quantity. I will guess that 3M will announce at least one design win at CES. QMC is still in the development phase but, says Doderer, “We believe our current trajectory will enable a recognized commercial electronics product launch in 2014 using Quantum Material tetrapod quantum dots.”

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