There have been tremendous gains being made in the field of printed electronics (PE), and a wide variety of ink manufacturers are developing inks that can be used in applications ranging from thin-film photovoltaics to printed batteries.
Photo courtesy of Novaled AG.
To be able to make the leap from theory to production is, of course, a critical step. With that in mind, Novaled AG, Dresden, Germany, a leader in OLED technology, and Plextronics, Inc., Pittsburgh, PA, a specialist in developing organic polymers, recently announced an agreement to jointly develop doped and solution processed organic materials for OLED applications.
Under the agreement, the companies will develop an advanced solution processible Hole Injection Layer (HIL) technology for OLEDs. By leveraging Plextronics’ organic conductive ink technology and Novaled’s organic dopant technology, the companies will target these advanced HIL materials for use with solution processed polymer and small molecule emitters, as well as with vacuum deposited small molecule emitters.
Novaled and Plextronics aim to offer a solution processed HIL with the same performance as a Novaled doped small molecule HIL deposited in a vacuum process. The Novaled doped HIL is part of the Novaled PIN OLED technology, which has demonstrated some of the highest power efficiency together with a long lifetime.
Plextronics and Novaled will also co-market Plexcore OC inks that incorporate Novaled dopant materials.
“Novaled is well-known for its power efficient OLED technology and is considered to be a world leading supplier of doping material,” said Andrew Hannah, president and CEO of Plextronics. “We expect that the combination of Plextronics’ conductive ink for OLED – Plexcore OC – and Novaled’s doping technologies will enable the high performance printing of OLED devices.”
“Plextronics is an international leader in organic ink,” added Gildas Sorin, CEO of Novaled. “It is Novaled’s strategy to partner with key industry players, like Plextronics, in order to enlarge our business offering for customers. Together with Plextronics, we are able to introduce the Novaled PIN OLED technology to the world of printed electronics.”
Anke Lemke, marcom officer for Novaled AG, noted that Novaled is well known for and positioned with its doping technologies and materials.
“The combination of Plextronics’ conductive ink with Novaled’s doping technologies will enable high performance OLED devices,” Ms. Lemke added. “OLEDs manufactured partly or fully by solution processing are promising for display and lighting applications. In our collaboration, we will concentrate on the first layer to be processed on the substrate. Solution processed hole-transport layers could be a replacement for vacuum processed hole-transport layers for some industries and applications.
“The envisioned p-type ink combines several advantages: solution processing of hole-transport layer increases the material yield as compared to vacuum processing and allows for smoothening of substrates roughness,” Ms. Lemke said. “This is important for large-area lighting products since finally it will enable a higher production yield.”
Jim Dietz, Plextronics’ vice president of business development, noted that the two companies have worked together informally for more than a year on this project. He added that Plextronics’ success in developing conductive inks for the OPV and OLED markets make it an ideal partner for Novaled.
“The output of the project is developing commercial worthy inks, so it’s a natural fit with Plextronics’ product development plans,” Mr. Dietz said.
“We gained quite some experience on dopants in solution processing in the past, and it turned out that with small molecules this kind of processing works very well,” Ms. Lemke added. “Plextronics and Novaled started to work on polymer solution processing several months ago. Our experience enabled us to further work closely together, to set up this collaboration and to offer the eventual results of our work to the market. We are targeting having products in place over the next several years.”
Ms. Lemke and Mr. Dietz noted that there are challenges to be met.
“For OLED display and lighting manufacturers, the key challenges remain improving efficiency and lifetime while developing a robust manufacturing process,” Mr. Dietz said. “The deliverables of this project are focused on meeting these challenges.
“Lighting companies are becoming more aware of OLEDs,” Ms. Lemke said. “However, concerning other OE markets, there are still some challenges that need to be solved, e.g. for the OPV efficiency has to exceed 8% and for ORFID, the manufacturing costs need to be below 1 cent at same performance level like current product solutions for non-organic electronics.”
Plextronics’ Plexcore OC conductive inks. (Photo courtesy of Plextronics)
“In contrast to conventional OLED, Novaled PIN OLED introduces an additional degree of freedom when it comes to product design,” Ms. Lemke added. “Hole and electron-transport as well as charge carrier injection are dramatically enhanced using Novaled PIN technology. As a result of doping, additional process steps, such as ITO treatment, are not needed. Additionally, a much wider range of materials used for the anode and cathode becomes available using p and n doping. In combination, this results in a very low driving voltage and high substrate compatibility of the Novaled PIN OLED. Meanwhile the highest possible power efficiency and the longest possible lifetime are maintained. Novaled has developed a number of doping and transport materials to be used in organic OLEDs to further enhance and support the already existing advantages.”
Ms. Lemke added that Novaled uses a number of different interlayers and emitter materials, which can be easily integrated into Novaled’s PIN structure. “Novaled is well equipped with advanced and state-of-the-art facilities and tools for providing customers with tailor-made prototypes,” Lemke concluded.
Both Plextronics and Novaled anticipate gains in the OLED market in the coming years.
“We expect rapid growth as our ink customers begin to make real traction in applying OLED and OPV to their market targets,” Mr. Dietz said.
“A new world of electronics: the organic electronics (OE) is in front of us,” Ms. Lemke said. “OE can be described as electronics and photonics products created with the use of organic materials. These materials may be semiconductive, light-emitting or photo active. OLED display and OLED lighting are two OE constituents besides a multitude of other applications under preparation, from solar cells to RFID.
“The OE move is comparable to the silicon move in the late 1970s,” Ms. Lemke added. “But contrary to the silicon world, requesting heavy industrial investments, organic semiconductors can be produced via printing technology and cheap vacuum deposition methods. The market expectations show a rapid growth in the coming years to reach a value above US $34 billion by 2014.”
Ms. Lemke noted that in several fields, organic electronics developed positively during the past one to two years, e.g. OLED lighting, AMOLED for display applications and flexible display, and that OLED technology is expected to become a major ingredient of flat displays and drive a new era lighting innovation with its flexible design and energy efficiency advantages.
“In OLED, we see a firm move towards products,” Ms. Lemke concluded. “For display, there are small products around for quite a while now (mobile displays), and companies like Sony started to offer also larger-size OLED displays for TV applications. For lighting, this has been especially noticeable in 2009 at the fairs, which tend to be at the front end of the year. A number of companies displayed OLED lighting prototypes at the Lighting fair in Tokyo in March, for example, Panasonic and Lumiotec. In Europe, Philips showed demonstrators at Euroluce in Milan in April this year. And even at the New York lighting fair, WAC Lighting had an OLED design on display. That was in addition to various announcements in the media, such as that from GE. This means that there has been much higher interest in OLED lighting.”