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Add-Vision’s Printed P-OLEDs Position Company for Success

By David Savastano

There are plenty of opportunities ahead for manufacturers of LED technologies, and not all of it is in the high-end applications. Companies that can successfully develop low-cost LED systems will find numerous possibilities for displays, backlights and lighting.

Among the intriguing companies in this growing field is Add-Vision, Inc., a small company that has developed a unique IP portfolio consisting of process, materials (inks) and device structure. Add-Vision has successfully created its LEDs entirely through traditional printing processes, and the company is well positioned in terms of partnerships to move quickly ahead.

Since its decision to focus on LED technology in 2001, Add-Vision has grown from a one-person start-up to its present success today. The company’s business model is to license its technology to manufacturing companies and sell its proprietary light emitting polymer (LEP) inks and cathode inks.

To date, Matthew Wilkinson, president and CEO of Add-Vision, noted that four major companies have been licensed, including Alps Electric ($6 billion in sales), Toppan Forms ($2 billion in sales), Bayer Material Science ($15 billion in sales) and CDT (Sumitomo Chemical).

Wilkinson said that his company’s mission has always been to develop low-cost, flexible light emissive displays, even when the company was developing thick film phosphor EL systems prior to its focus on LEDs.

“Prior commercial experience in thick film, phosphor EL, keenly demonstrated the need for a new, higher performing technology platform that retained the same attractive manufacturing model and physical characteristics (thin, flexible, patternable),” Wilkinson said. “Our goal is to pick up where EL left off as well as enabling new market opportunity for fully printable, flexible, low cost LEDs.”

Add-Vision has already enjoyed success in military applications, and has its eye on the consumer market. Potential applications include smartcards or gift cards, promotional products, games and toys, consumer electronic devices, signage, white goods and automotive.

“It has never been our desire or intent to compete in the mainstream, high information content marketplace, but instead to develop and offer a solution for cost-effective, high-performance backlights, low information content displays, and specialty lighting,” Wilkinson added.

The key to Ad-Vision is its P-OLED technology, which the company is able to print using screen, gravure and flexo processes.

“A key characteristic of Add-Vision’s technology is our fully printable, manufacturing process,” Wilkinson said. “There are no vacuum deposition processes; every layer of our simple three layer device is printed under normal atmospheric conditions.

“In order to achieve our low cost model, we required that the deposition of each layer of the device be accomplished with, fundamentally, ordinary printing equipment using standard methods,” he noted. “This required significant materials development, namely special LEP inks and cathode materials.”

The company produces its P-OLED displays in four steps. First, Add-Vision screen prints a resist, and etches away the ITO. Next, the company uses gravure to deposit its LEP inks in a thin layer. The cathode is then screen printed, as is the final coating. The key is the printing of the cathode layer.

“In a standard OLED device, careful selection of the electrodes is required in order to achieve efficient charge injection into the semiconducting polymer,” Wilkinson said. “In the case of the cathode, this requires a low work function metal. The low work function cathodes in the standard OLED device are non-air stable and are deposited by vacuum deposition.

“Furthermore, the instability of cathodes make devices made on plastic substrates impractical due to moisture and oxygen ingress which rapidly causes black spot formation due to oxidation of the cathode,” he added. “While plastic barrier substrate technology is improving, defect rates are still too high, with web-based (high volume) produced material, to achieve device lifetimes suitable for most products in the case of devices with non-air stable cathodes. Add-Vision’s air stable cathode not only allows us to deposit or print the cathode using screen printing, gravure or flexographic methods, but also reduces the moisture vapor transmission rate requirement of the plastic barrier substrate.”

Wilkinson said that the development of doped LEP inks enables the use of relatively high work function metal cathodes.

“Add-Vision uses ionic dopants in the LEP layer to create, in situ, a P-i-N device structure,” he said. “This device technology is also known as electrochemical cell from the early work done by Dr. Alan Heeger and others at Uniax. Historically, challenges with the electrochemical cell approach have included short lifetimes and long turn on time. Add-Vision has developed proprietary inks and simple device structure that has resulted in devices with lifetimes exceeding 10,000 hours (with 100Cd/m2 peak brightness) and turn-on times <0.5 sec. This performance level exceeds most of our initial application requirements.”

As a result, Add-Vision’s P-OLED displays offer excellent brightness and color while using low voltage DC drives, and are thin and flexible, allowing the displays to be used in unique applications. By printing their displays, Add-Vision is also able to keep costs low.

Wilkinson also noted that Add-Vision continues to make gains in its P-OLED technology, reaching 11,000 hours lifetime.

“We have made very good progress in device lifetimes, device efficiency, turn on time, improved ink deposition processes and overall manufacturability,” he added.

Wilkinson believes that the merger of Add-Vision’s technology and the changing face of electronics in our lives are indeed a case of perfect timing.

“Our lives are filled with tools, equipment and electronic devices that all require some form of human interface,” Wilkinson concluded. “Add-Vision’s technology provides a compelling solution for designers of these products to provide for communication and lighting to users in a very cost effective way. In the field of printed electronics which includes transistors, diodes, photovoltaics, reflective displays, batteries, antennas and other passive components, Add-Vision’s goal is to be the leading provider and developer of light emissive devices. Add-Vision has created a unique market opportunity inside the field of printing electronics by developing a one-of-a-kind light emissive technology that is completely printable of flexible substrates.”