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Printed Electronics World
Posted on May 21, 2007 by  & 

Add-Vision Extends Life of Low Cost Flexible OLEDs

Add-Vision, Inc. has successfully demonstrated its first fully printed Organic Light Emitting Diode (P-OLED) device that exceeded 1,000 hours of operating lifetime at peak luminance of 100cd/m2. The polymer OLED ie P-OLED devices were screen-printed under ambient conditions onto thin flexible substrates. This represents more than a doubling of the operating lifetime results from August 2006, and positions the technology for near-term commercialization in a range of applications. This performance level matches a range of high-performance applications, in the opinion of the company. It says they include illuminated keypads, secondary displays, interface panels, light-emissive switches and other electronic components, representing a collective market size exceeding several billion dollars in opportunity.
 
"The 1,000-hour milestone is a key commercialization target for our partners and customers," said Devin MacKenzie, director of technology. "This performance level exceeds commercialization thresholds in a number of high-volume consumer applications. In the short-term, I believe our accelerating progress in printed P-OLEDs is on track to surpass the operating lifetime specifications of thick-film EL. In addition, the P-OLED technology enables higher brightness, low DC voltage operation, superior color and lower total system cost."
 
 
IP from CDT and internal resources
 
Add-Vision Inc (AVI) is an example of a company using CDT intellectual property and adding its own in order to make saleable products even within current constraints of lifetime of flexible OLEDs. In 2007, this P-OLED display technology is being sold as a product into the U.S. military for night vision operations. Add-Vision is further progressed than most in producing a range of printed, affordable, flexible OLED devices.
 
Add-Vision has a screen printed flexible display using Light Emitting Polymer (LEP) that is almost ready for general commercialisation in 2007. The structure mimics the simple capacitor-like structure of inorganic AC electroluminescent displays with the only non-printed part being the indium tin oxide ITO semi‑transparent electrode which is patterned to give blocks of colour or alphanumerics. There should therefore be few problems of registration.
 
 
For commercial applications, the technology is still about 12 months away for full commercial production. Add-Vision is a licensing company and it has about 4-5 companies that are now trying to scale up the manufacturing to high volume, for everything from light-emissive direct mail, in-store signage to backlighting keypads on mobile handsets. These are all passive displays ie with predefined areas of colour that can be switched in sequence, not active dot matrix. They would compete with alternative passive displays such as the ac electroluminescent displays of Pelikon and Schreiner, probably offering a better range of colours and low voltage as advantages. However, it will be some time before P-OLED can provide wide area to compete with the ac electroluminescent billboards and architectural features of elumin8.
 
Great progress
 
AVI has made great strides in printed OLED technology for low-resolution displays and specialty lighting applications. Work in light-emitting polymer (LEP) materials, ink formulations and print processing showed significantly improved performance and yield, while cathode improvements lowered operating voltage and increased power efficiency. Today, several key technical and commercial milestones have been established towards commercialisation of printed OLEDs.
 
These include:
 
  • Substantial improvement in operating lifetime
  • Demonstration of improved printing yield
  • Improved power efficiency through cathode development
  • Formation of close relationships with LEP and barrier-substrate developers leading to higher availability and performance of related materials
  • Strong commercial demand, including evaluation licensing, capital investment, product demonstrators, and manufacturing Joint Development Agreements (JDA) with several global electronics manufacturers.
 
 
AVI uses a simplified P-OLED device structure with a proprietary doped Light-Emitting Polymer (LEP) layer. The doped P-OLEDs provide high brightness, high-efficiency operation while having an air-stable cathode. Every layer of the device can be patterned through printing, eliminating expensive evaporation or vacuum processing steps. The resulting P-OLEDs retain many of the attractive characteristics of traditional RGB OLED technologies (low DC voltage, high brightness, etc) while being low cost to produce.
 
Print-based manufacturing
 
AVI has been able to approximate the high-volume, low-cost manufacturing methods typical of the graphic printing industry, not the LCD display industry. The result is a low-cost process, similar to thick-film EL or membrane switch manufacturing. Except for a final encapsulation step, the entire OLED display manufacturing takes place in air, using only conventional printing equipment and methods. This represents a radical departure from conventional OLED approaches. A single AVI OLED manufacturing line would cost les than $1 million in equipment, but could produce 30,000 SF/month of flexible P-OLED display products to generate $18 million per year.
 
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