This breakthrough highlights new possibilities for integrating high-definition full color displays in wearable electronics.
The scientific team, from the Institute for Basic Science (IBS) and Seoul National University, has developed an ultra-thin wearable quantum dot light emitting diodes (QLEDs). The electronic tattoo is based on current quantum dot light emitting diode (QLED) technology. Colloidal quantum dot (QLED’s) have attracted great attention as next generation displays. The quantum dots (QDs) have unique properties such as the color tunability, photo/air stability, and are printability on various substrates. The device is paper thin and can be applied to human skin like a sticker.
The team developed the high performance red, green, and blue QLED array, whose resolutions approach 2,500 pixels per inch. This resolution is far superior to other light emitting devices and displays on the market today including ones used in the latest smartphones. The technique is readily scalable over large area. Devices are adaptable to deformed states and thereby built on the unconventional curvilinear substrates including surfaces of various objects. Further mechanical deformations, such as stretching or wrinkling, are also adopted in this technology, which enables QLEDs on the human skin. This breakthrough highlights new possibilities for integrating high-definition full color displays in wearable electronics.
Read more: QLEDs Meet Wearable Devices
Princeton University researchers have developed a new method to increase the brightness, efficiency and clarity of LEDs, which are widely used on smartphones and portable electronics as well as becoming increasingly common in lighting.
Using a new nanoscale structure, the researchers, led by electrical engineering professor Stephen Chou, increased the brightness and efficiency of LEDs made of organic materials (flexible carbon-based sheets) by 57 percent. The researchers also report their method should yield similar improvements in LEDs made in inorganic (silicon-based) materials used most commonly today.
The method also improves the picture clarity of LED displays by 400 percent, compared with conventional approaches. In an article published online August 19 in the journal Advanced Functional Materials, the researchers describe how they accomplished this by inventing a technique that manipulates light on a scale smaller than a single wavelength.
“New nanotechnology can change the rules of the ways we manipulate light,” said Chou, who has been working in the field for 30 years. “We can use this to make devices with unprecedented performance.”
A LED, or light emitting diode, is an electronic device that emits light when electrical current moves through two terminals. LEDs offer several advantages over incandescent or fluorescent lights: they are far more efficient, compact and have a longer lifetime, all of which are important in portable displays.
Current LEDs have design challenges; foremost among them is to reduce the amount of light that gets trapped inside the LED’s structure. Although they are known for their efficiency, only a very small amount of light generated inside an LED actually escapes.
“It is exactly the same reason that lighting installed inside a swimming pool seems dim from outside – because the water traps the light,” said Chou, the Joseph C. Elgin Professor of Engineering. “The solid structure of a LED traps far more light than the pool’s water.”