Quantum Materials is the new quantum dot (QD) 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 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.
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 displays, QDs are used to modify the backlight unit of an LCD. Instead of using white LEDs, QD-enhanced backlights use less expensive blue LEDs, and two sizes of QD convert some of the blue light into red and some into green. The red and green can have particular wavelength desired, and can contribute to a wider color gamut than traditional LCDs with conventional backlights. This combination of wide gamut and narrow emission peaks can give LCDs an appearance that is surprisingly similar to that of an OLED, and the cost increase over conventional LCDs is slight.
For all of their differences, the QDs made by QD Vision and Nanosys 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 recent conference call, 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.
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.”
Ken Werner is the founder and principal of Nutmeg Consultants. He can be reached at firstname.lastname@example.org.
Posted by Ken Werner, December 26, 2013 4:34 PM
About Ken WernerKenneth I. Werner is the founder and Principal of Nutmeg Consultants, which specializes in the display industry, display technology, display manufacturing, and display applications. He serves as Marketing Consultant for Tannas Electronic Displays (Orange, California) and Senior Analyst for Insight Media. He is a founding co-editor of and regular contributor to Display Daily, and is a regular contributor to HDTVexpert.com and HDTV Magazine. He was the Editor of Information Display Magazine from 1987 to 2005.