Printed Electronics Make Gains, But There are Challenges Ahead
The printed electronics industry in Europe is enjoying growth, but obstacles such as pricing and further technological improvements remain.
By Sean Milmo
Europe’s fledgling printed electronics sector is beginning to move into the marketplace after years of
The arrival at the first stages of commercialization has boosted morale in the sector. But European companies involved in printed electronics are also warning that many obstacles still have to be overcome, not only in improving the technologies but also in achieving competitive costs.
At the same time, there is an even stronger belief in the enormous potential of these new, low-cost electronics. This is especially the case in Germany, where much of the work on the commercialization of the new technologies is taking place because of the country’s strength in printing, engineering and chemicals.
Solar energy is one segment in printed electronics in which there are rising hopes of a major breakthrough in terms of technology and production processes. Germany is currently a worldwide leader for the application of solar cells for the generation of heating and electricity.
The mixture of optimism and caution was evident at a conference on printed electronics organized by the German-based Organic Electronics Association (OE-A) at drupa 2008.
“In conventional electronics, computing power has been doubled on average every 18 months,” said Arved Huebler, managing director of printed systems, a printed electronics startup at Chemnitz, Germany. “But the traditional electronics sector has not created a new price dimension. In fact, the cost of a PC over the last 17 years has gone down by an average of 4 percent every 18 months. Prices in the printing industry have been reduced by 3 percent annually since 1991.
“Printed electronics, on the other hand, provide opportunities for a new dimension in prices,” he added. “We have materials which give us new options, like small molecules and polymers and nano particles and printing processes for large-scale production from them. ‘Printronics’ is a totally different approach to electronics.”
He compared his company, a specialist in the printing of polymer-based memories on paper, cardboard and foil and a spin-off from Chemnitz University of Technology, to Scandisk, a global leader in the production of electronic memory devices. While Scandisk with personnel of 2,500 makes 308,000 flash memories on silicon wafers with a memory space up to 1 gigabyte at a price of $27.31 per unit, his company with a staff of 25 is able to produce 300,000 paper cards with electronic memories of a 96-bit capacity at a unit price of 1 U.S. cent.
Printed systems has developed a technology for placing a 2-micron thick layer of printed polymer memory between two layers of paper to form a color printed card. The unit production cost of the memory and finished care is €5-7 cents (8-11 U.S. cents). The data in the near-field, intelligent paper (NF-IP) card can be transferred via a plug-and-play reader costing €4 to a PC, TV set decoder or play station.
Earlier this year, the company reached a deal with Deutsche Post, which undertook to distribute 500,000 readers to German households to enable data from the NF-IP cards to be transmitted to game stations or PCs with Internet access.
“The attraction of the cards will be that they will enable games to be played with them, but for brand owners they will be a vehicle for advertising their products,” said Mr. Huebler. “For us, 2008 could be the year in which we made the big breakthrough because we will have introduced our technology into private homes.”
Printed systems sees its NF-IP card as a means of linking the printed media, comprising conventional mass printing and office and digital print-on-demand printing, and the electronic media, ranging from TV and radio to the Internet and electronic paper.
“The print media market is currently worth around €1,000 billion with growth at 3 percent per year, while the electronic media market is worth €450 million with growth at 8 percent annually,” Mr. Huebler said. “Printed electronics is in a good position to bridge the gap between the two. Our first aim is to establish our technology for future generations by making it active in private homes.”
In addition to having applications within the home, the NF-IP card can be connected with mobile phones as a navigator and for access to E-books. It can also be used for item tagging of industrial products through short-distance reading for identification and to combat counterfeiting, and adapted for long-distance reading for applications as an RFID tag.
Because the NF-IP tags are fully printed, they can be sold at prices more than 10 times less than RFIDs, the vast majority of which are partly printed or wholly produced by non-printing processes. Printed systems believes that RFIDs will not be able to match the unit production costs of its cards until around the middle of the next decade, when the numbers of RFID tags on the market will be close to 1 trillion, because by then the vast majority of tags will be fully printed.
PolyIC, Fuerth, Germany, a joint venture between the hot stamping and printing coatings company Leonard Kurz GmbH & Co. and Siemens AG, the electrical engineering and electronics giant, has been among the first European companies to introduce a printed RFID into the market. The launch has taken nearly four years of development, but the company stresses that there is still much more R&D work to be done.
“We are taking a step-wise approach, because to get to the levels we are satisfied with will take some time,” said Wolfgang Mildner, PolyIC’s managing director. “Nonetheless, we feel that the numbers of printed RFIDs on the market will overtake the numbers of silicon-based RFIDs in 2010 because by then the technology will be applied on a wide scale to individual consumer items.”
PolyIC is commercializing its RFID technology after advancing it along three parallel development tracks. These involve its clean room for the creation of chip design and materials, a printing laboratory for testing formulations and reel-to-reel (R2R) equipment for making low-cost, high volume products with flexo, offset, gravure and screen processes.
“We decided that inkjet is not fast enough for our production methods,” said Mr. Mildner. “Maybe we will change our views in the future because inkjet is improving a lot.
“It’s a complex task getting the right parameters to achieve high performance and reliable printed electronics,” he added. “With materials, for example, people think mobility is the driving factor. But work function, contact resistance, regioregularity (semiconducting properties) and the adequacy of the solvents are also important. With the printing process, visual inspections to determine resolution are not good enough. We need to find a reel-to-reel system of quality control. Once you’re printing at full speed, you don’t know what resolution you are producing.”
Professor Harri Kopola, director of printed intelligence at VVT Technical Research Centre in Finland, acknowledged that printed electronics would make increasing demands for greater quality and process controls, particularly since the range of production processes is widening. In addition to continuous R2R and digital printing, printed electronic products can be made through systems like hot embossing, lacquering, coating, laser processing, electric sintering, lamination and a variety of hybrid processes.
Components like optoelectronic devices, sensors, indicators and power sources can also be integrated with printed systems on web, sheet or foil, Professor Kopola said. This is the case with OLED displays, signage, solar cells and miniaturized fuel cells.
VTT has been developing methods for the full printing by R2R of flexible OLEDs. These could include the printing of layers and components with indium tin oxide and PET (ITO-PET), conductive polymers like polyethylenedioxythiophene-polystyrenesulfonate (PEDOT/PSS) and benzothiadiazole-based hyperbranched polyfluorenes (PFBT) and silver supporting lines.
Professor Kopola’s research team has also been working on the gravure printing of organic solar cells on flexible ITO-PET with hole transporters and active layers and a power conversion efficiency of 4.5 percent.
Michael Heckmeier, director of Merck Chemicals, Chilworth, England, said his company, the organic electronics subsidiary of Merck KGaA of Germany, produces a polymer-based material specifically for application in organic photovoltaics (OPV).
The material currently has an energy efficiency of 5 percent. An objective of a €300 million ($475 million) OPV research project involving Merck and three other German companies – BASF AG, Schott AG and Bosch Group – is to develop materials with an efficiency of 10 percent.
“The chemical structure and design of materials for photovoltaics is similar to those for OLEDs,” said Mr. Heckmeier. “With photovoltaics, the source of light is converted to electricity, while with OLEDs, the electricity is converted into light.”
Merck is concentrating on the development of materials and printable formulations for organic electronic applications, and is involved with partners in projects for the co-development of printing processes and of components and devices.
The company is currently making polymer materials with a mobility equal or in excess of that of amorphous silicon at approximately 1 square centimeter per volt second (cm2/Vs). Now the aim is to reach mobility levels at around 10 cm2/Vs, which would be similar to those of polysilicon, the material currently used in solar photovoltaics.
“With optimization, new organic materials developed over the next years and produced on a mass scale will have a mobility of 10 cm2/Vs,” Mr. Heckmeier predicted.
With production processes, Merck has been moving from the simple and well established process of spin coating to inkjet, which it considers uses materials more efficiently and requires low capital investment. Inkjet also has the advantages of being contactless and being able to do direct digital patterning, while it can also print large areas.
“Inkjet is our number one choice,” said Mr. Heckmeier. “But flexo is something we are also working on.”
Over the next few years, matching materials with the most suitable and cost effective processes is likely to be a priority among companies in printed electronics in Europe.