RESEARCHERS BUILD NEXT-GENERATION FLEXIBLE DIGITAL DISPLAYS
Professors Bernard Kippelen and Seth Marder of the Center for Organic Photonics and Electronics (COPE) at Georgia Tech are developing light-emitting diodes (LEDs) using organic elements — principally carbon, hydrogen, oxygen, and nitrogen — that abound in Earth’s biosphere.
The resulting organic LEDs (OLEDs) are both flexible and shatterproof. They could replace or augment digital displays currently used in cell phones and TVs, while also offering new ways to light everything from a tiny medical probe to entire interior surfaces.
(Click to enlarge.) Slender, flexible OLED devices are being developed by combining several ultra-thin layers to create a light-emitting surface. The total device thickness of such a screen is about 100 nanometers — far thinner than a single human hair. Graphic: Canek Fuentes-Hernandez.Most digital devices today use displays made with indium tin oxide that is deposited onto a glass substrate. Such displays are generally both inflexible and brittle. Moreover, the relatively high price of indium, a rare earth element, adds significantly to manufacturing costs.
By contrast, the COPE team uses low-cost, Earth-abundant organic materials to fabricate a display surface that can produce plentiful light from a small amount of electric current. The researchers deposit exceedingly thin metal foils and films of organic molecules on a very thin plastic substrate. The total device has a thickness of about 100 nanometers – much thinner than conventional displays, which can be up to a millimeter thick.
COPE’s current device fabrication method involves evaporating organic molecules using extreme heat and then depositing them onto a plastic substrate. In the future, however, OLED light-emitting surfaces could be manufactured using roll-to-roll printing processes. This approach promises to yield large display surfaces capable of showing video or providing customizable lighting sources covering entire walls or ceilings.
Because they’re flexible, OLEDs can also conform to curved surfaces. That capability would allow them to serve as light-emitting surfaces in tight places such as medical catheters, or to provide illumination for optics and protective gear used during surgery.
COPE’s approach also promises environmental benefits. The organic materials used by the light-emitting foil and its substrate can be designed to be biodegradable. Unlike conventional displays, which may contain elements that are toxic and costly to recycle, an OLED display could be recycled by simply being dissolved in water at room temperature.—RICK ROBINSON
