Few display technologies rival the visual brilliance and energy-saving potential of organic light-emitting diodes (OLEDs). Yet OLED displays are mostly found in smaller applications like mobile phones. The manufacturing technology for OLEDs has struggled to scale up for mass producing computer monitors or televisions.
Now QD Vision, an MIT spinoff, has announced a display technology based on quantum dots that could not only be easier to manufacture than OLEDs, but also be even brighter and more energy-efficient.
Last week, the Massachusetts company announced a partnership with major manufacturer LG Display to develop displays that use quantum-dot light-emitting diodes (QLEDs) as their pixels. In early November, QD Vision also partnered with Solvay, a Belgium-based chemical company, to build a platform for printing QLEDs.
Quantum dots are nanometer-sized semiconducting crystals that can shine a bright, spectrally pure color when exposed to either light (photoluminescence) or electrical current (electroluminescence). QD Vision’s first product, a quantum dot optic that warms the normally harsh glow produced by LED lamps, relies on photoluminescence; the quantum dots emit color when light from the LEDs excites them.
Silicon Valley-based Nanosys, another company working with quantum dots, expects to have its own product available in early 2011. Nanosys adds a strip of quantum dots to a liquid-crystal display’s backlight to improve color quality and energy efficiency. QD Vision is developing a similar product.
To use quantum dots as the main element in a display, the crystals need to be excited by electrons, not photons. “[Electroluminescence of quantum dots is] something we’ve been working on a very long time, and now it’s getting to this point of commercial traction,” says Seth Coe-Sullivan, QD Vision’s chief technology officer.
The target is the OLED market. “Small OLED displays are getting very good market traction,” says Coe-Sullivan, “but there are still some unresolved challenges with OLEDs, and we see QLEDs as a way to solve them.” The main benefit of QLEDs over OLEDs, he says, is in manufacturing. “There’s been lots of proposals for manufacturing OLEDs at a larger scale, but none of them have worked out.”
OLEDs need to be patterned as they are deposited, something that’s traditionally been done with something called a shadow mask. But due to the chemical properties of OLEDs, the shadow mask technique isn’t accurate at larger sizes. QLEDS, in contrast, don’t need a shadow mask. They can be suspended in a liquid solution, which allows them to be deposited using any number of scalable techniques, including ink-jet printing.