Quantum Dots: The End of White LEDs in Backlights?

In late January, Nanosys announced it had signed a "definitive commercial agreement" with LG Innotek (LGIT) for the use of Nanosys’ quantum-dot phosphors in displays. The agreement "represents the first real world commercial application of quantum dots in electronics," the Nanosys announcement said. LGIT seemed equally enthusiastic. "Nanosys’ Quantum Rail technology is a solution ready for integration into backlight sub-assemblies without major tooling changes, making it our first choice for our next-generation high color gamut displays," said Charlie (Cheol-Kee) Hong, LGIT VP and head of the company’s R&D Center.

Nanosys fabricates what it calls a Quantum Rail (QR), a continuous component consisting of quantum dot phosphors in a polymer matrix. In a typical LCD edge light application, the QR is fastened with optical adhesive to the strip of blue LEDs that are the light source for the BLU. The "green" quantum dots down-convert the blue light to narrow-spectrum green and emit it into the light-guide plate. The "red" QDs do the same for red. The mixture is also carefully balanced to allow just the right amount of blue light into the light guide, too. This results in narrow-spectrum light sources for R, G and B, whose peaks can be tuned to suit the needs of the application. It produces a triangular color gamut that exceeds 100 percent of AdobeRGB and is considerably greater than the gamut of conventional modern LCDs. It also provides an improvement of 20 percent in power efficiency compared to existing backlight solutions, says Nanosys, probably because the color filter transparency can be increased due to the improved spectrum.