Applications

Use in Displays

Do you know that most 4K and Ultra High Definition televisions (TV) available today contain Quantum dots? There are billions of these spherical crystal nanoparticles inside a 55” High Definition TV screen.  The deep physics of Quantum dots is the reason for the lifelike picture quality and increased energy-efficiency of these TVs. Quantum dot colors are so pure that it can show you more colors than ever before. According to television maker Samsung, “Quantum dot colors are so pure that it can show you more colors than ever before, about one billion. That’s 64 times as many colors as a conventional TV.”

In the most widely produced liquid crystal displays (LCDs), the primary colors, red, green and blue (RGB), are mixed in various proportions at the sub-pixel level using active matrix filters that are lit from behind with a source that contains all three primary colors. This produces a display with a wide color gamut–defined by connecting the points representing the primary colors in a particular color space. Any of the colors inside the R-G-B triangle can then be produced by varying the intensity ratios of the primary colors. The boundaries of the color space are defined by monochromatic light, so the narrower the emission spectrum of the primaries is, the larger the color gamut is. In this regard, QDs have a big advantage over light emitting diodes (LED); the emission bandwidth of red and green QDs are typically below 30 nm (full-width at half maximum-FWHM) where as those of LEDs are 40 nm and larger.

fwhm-to-color-gamut

Navillum QDs that are manufactured using our patented low-temperature, near-thermodynamic equilibrium process yields consistently high-quality QDs which are capable of serving as primary color sources for the full rec. 2020 color gamut specification, the upcoming standard for the next generation of high definition displays. Rec. 2020 is the International Telecommunications Union (ITU) Recommendation Standard, BT.2020. ITU is one of several organizations that sets standards upon which production, broadcast and display industries rely to ensure that produced content is being accurately transmitted and faithfully displayed. Navillum will work with your company to provide QDs that when combined with your active matrix filters will optimize the gamut coverage of rec. 2020 or otherwise tailor the display gamut you require. We have shipped QD samples to display partners and currently exploring QD solutions to niche display applications.

Use in Solid-State Lighting (SSL)
Existing solid-state lighting (SSL) systems produce white light of poor quality (as defined by the color rendering index, CRI) and of limited color temperature range (typically only 4500-6500 K). This white light is typically produced by one of several methods that utilize blue LEDs and rare-earth phosphors, which down-convert the blue light to colors of longer wavelengths. An additional problem with these methods results from the fact that the narrow absorption spectra of the phosphors used capture only a small fraction of the light emitted by the blue LEDs; hence, the methods are not energy efficient.

cie-diagramA potential solution to address many of the problems inherent in current SSL technologies is to substitute QDs for phosphors. QD emissions are tunable so they can produce very high quality white light of virtually any color temperature. They also have strong, broad absorption features that couple with great efficiency to blue-LED emitters.

abs-and-plIf QDs could be employed effectively enough to achieve the 200 lumens per watt (lm/W) goal of the U.S. Department of Energy Luminaire Efficacy Program, they would have achieved huge energy savings that should accelerate the commercial adoption of SSL systems dramatically.

Navillum is currently working with lighting partners to achieve the best QD solution for the SSL market.

Energy Efficiency and Efficacy
Since the bandpass of the RGB filters in LCD displays is wider than that of the QDs, less of the emitted light is filtered out and turned into heat than in the case of LEDs. This makes displays consisting of a blue LED and down-converting red and green QDs electrically much more efficient than all-LED displays. This is particularly important for battery operated, mobile applications where higher energy efficiency means longer battery life and for solid state lighting where producing more light in the visible spectrum (efficacy) and less heat with the available electrical power is becoming a national imperative. Controlling the emission wavelength is also important in applications where display emission at longer wavelengths (i.e. red to infrared region) can interfere with night vison systems and can be a safety and operational hazard.

Navillum’s synthesis process can easily produce QDs with exact specifications at high precision, such as red-emitting QDs with controlled long-wavelength emission. Our QDs have emission wavelengths that can be produced consistently at very narrow bandwidths. We also have the technical expertise to assist in formulating the custom QD solution to fit your application. Contact us now for more details.