OLEDs are promising for the next generation of displays and solid state lighting because they use less power and can be more efficiently manufactured than current technology. However, the intrusion of moisture into the displays can damage or destroy an OLED’s organic material.
“OLEDs have better color and flexibility and the capability of larger displays, but companies still need an inexpensive encapsulation method that can be used to mass produce organic electronics that don’t allow moisture in,” said Wusheng Tong, a senior research scientist at the Georgia Tech Research Institute (GTRI).
Manufacturers now seal displays in an inert atmosphere or in a vacuum environment. They glue a glass lid on top of the display substrate with a powder inside the display to absorb moisture that diffuses through the glue. These seals are expensive and labor-intensive to assemble.
With funding from GTRI’s independent research and development program, Tong and his GTRI collaborators – senior research scientist Hisham Menkara and principal research scientist Brent Wagner – have replaced the glass enclosure with a thin-film barrier formed by a less expensive conventional deposition method.
“We chose a passivation coating process that could be performed at room temperature so that the organic material remained intact,” said Tong.
The researchers selected advanced ion assisted deposition, which utilizes reactive ions to deposit a high-density, pinhole-free thin silicon oxynitride (SiON) film on the OLED surface.
“Ideally, the film should be as thin as possible, but if it’s too thin, a pinhole or other defect could appear and cause a problem,” explained Tong. “We found that a film of 50-200 nanometer thickness was perfect.”
During testing, the SiON-encapsulated OLEDs showed no sign of degradation after seven months in an open-air environment, while the OLEDs without the coating degraded completely in less than two weeks under the same conditions.
When Tong conducted accelerating aging tests in an environmental chamber that maintained a temperature of 50 degrees Celsius and 50 percent relative humidity, the OLEDs encapsulated with SiON films showed little degradation for at least two weeks. The OLEDs without encapsulation, however, decomposed immediately.
“We’ve demonstrated that this deposition process improves the lifetime of the OLEDs by blocking the intrusion of moisture, so now we’re hoping to work with industry partners to develop a mass production process for our encapsulation technique,” added Tong.
Source: Georgia Institute of Technology
Related stories:
Nanoengineered barrier invented to protect plastic electronics from water degradation
A breakthrough barrier technology from Singapore A*STAR’s Institute of Materials Research and Engineering (IMRE) protects sensitive devices like organic light emitting diodes (OLEDs) and solar cells from moisture 1000 times more effectively than any other technology available in the market, opening up new opportunities for the up-and-coming plastic electronics sector.
A better image for plastic solar cells
A new way to help technologists develop efficient and inexpensive plastic electronic devices, such as plastic solar cells and a new type of transistor was showcased by physicist Andrea Liscio, who is supported by the European Science Foundation, at the EMRS (European Material Research Society) Spring Meeting held in Strasbourg, France at the end of May.
Idemitsu, Sony Achieve World's Highest Level Of Luminous Efficiency For Blue Fluorescent
Idemitsu Kosan and Sony today announced the achievement of 28.5% internal quantum efficiency (IQE) in deep blue fluorescent OLED devices, the world's highest level of luminous efficiency for this technology.
Engineers make first 'active matrix' display using nanowires
Engineers have created the first "active matrix" display using a new class of transparent transistors and circuits, a step toward realizing applications such as e-paper, flexible color monitors and "heads-up" displays in car windshields.
Alienware's Giant Curved Monitor a Gamer's Delight
One of the more intriguing technologies at the Consumer Electronics Show (CES) being held this week is a 42-inch-long, curved monitor. Made by Alienware, the monitor is supposed to simulate peripheral vision. The sci-fi-like screen is aimed at gamers for a more immersive experience, although it might not be as suitable for design or text work.
Philips Lighting The Way Through the 21st Century
Philips scientists envision a future of eco-friendly and aesthetic lighting solutions for consumers. Their R&D work in the area of OLED lighting will bring light to walls, ceiling, furniture, windows and most surfaces. The lighting effects that will be created by this new technology are revolutionary.
New Flexible, Transparent Transistors made of Nanotubes
The ability to create flexible, transparent electronics could lead to a host of novel applications, such as e-paper and electronic car windshields. Now, scientists have constructed a transistor made of a network of nanotubes that may serve as an essential component in a trans-flex device.
Simple OLEDs ready for quick manufacturing
With their attractively low energy consumption, Organic Light Emitting Diodes (OLEDs) are widely predicted to replace the LCDs now used in the large screens of laptops and TVs. Currently, OLEDs are commonly used in small portable devices such as cell phones, but adapting them to large screens will still require a few modifications.
