A joint U.K.-Dutch research team has made a key breakthrough that could lead to brighter and more energy-efficient OLED TVs, with longer battery lives for smaller devices utilising the display technology
The team of researchers from Cambridge University and the Eindhoven University of Technology said their discovery pertains to a novel technology known as “chiral semiconductors”, and finds that they can dramatically improve the brightness and efficiency of OLED displays.
According to the researchers, today’s OLED televisions make use of polarisation layers, which are used to prevent light leaking outside of the display. They’re a key component of OLED displays and a big part of why they’re able to produce such accurate contrast, but they’re also a massive energy hog. That’s because they absorb more than 50% of the light generated by the OLED pixels in order to prevent it “leaking”. That absorption means a lot of wasted energy.
In other words, polarisation is incredibly efficient, but chiral semiconductors promise to be an immense improvement.
These special semiconductors emit “circularly polaris light” that’s able to carry “information about the left- or right-handedness of electrons”, the researchers explained. That’s because chiral molecules used in them can be either left- or right-handed, and they mirror one another, whereas normal silicon chips use symmetrical molecules.
The best known example of a chiral molecule is probably DNA strand, which form the so-called double helix.
These details have been known for a long time, but it has proven to be extremely difficult to manufacture chiral semiconductors. Until now. Taking inspiration from nature, the research team led by Professor Bert Meijer (above) from the Eindhoven University of Technology was able to build left- and right-handed spiral columns using semiconductor molecules. These columns can form the basis of chiral semiconductors, the researchers say.
“Unlike rigid inorganic semiconductors, molecular materials offer incredible flexibility – allowing us to design entirely new structures, like chiral LEDs,” said Professor Sir Richard Friend of Cambridge University. “It’s like working with a Lego set with every kind of shape you can imagine, rather than just rectangular bricks.”
“By carefully designing the molecular structure, we’ve coupled the chirality of the structure to the motion of the electrons and that’s never been done at this level before," added Meijer.
The team has created a prototype chiral semiconductor using a special material called triazatruxene, which is known as TAT. It possesses unique properties that allow it to self-assemble into a Helix shape, and then electrons can spiral across it. The researchers liken it to the head of a screw.
The theory is that these structures can be used to make more efficient polarising components for OLED displays.
"We’ve essentially reworked the standard recipe for making OLEDs like we have in our smartphones, allowing us to trap a chiral structure within a stable, non-crystallising matrix,” said Rituparno Chowdhury, one of the authors of the paper.
According to the researchers, these new polarised LEDs can support vastly improved efficiency and brightness, superior to anything used in the OLED display industry today.
As with all research, the new technology is still likely to be years away from commercialisation, so don’t expect to see any dramatic improvements in OLED TVs soon. But it's still an exciting development, and there is hope that it may be bolstered by other recent scientific discoveries. In February, another U.K.-based research team revealed it had come up with a way to manufacture more energy-efficient and lower cost blue OLED pixels, potentially paving the way for cheaper and better-quality OLED TVs in the future.
Chiral semiconductors can also help to advance other industries, including quantum computing and an area of research known as “spintronics”, which involves using the spin of electrons to store and process data. The development may one day lead to much faster and more efficient computers, the researchers said.
