Plastic Logic Device Showcases Organic Transistors
New e-reader is the first product to use them.
Today at the Consumer Electronics Show in Las Vegas, Plastic Logic announced the details of the first consumer product based on organic transistors, a technology that’s been limited to the lab for the past 20 years. The company’s thin, lightweight e-reader, called the Que, uses organic transistors to power a black and white, touch-sensitive display made by E Ink, an electronic paper company. Such transistors can be built on lightweight plastic backings.
For the Que, the organic transistors mean a large and lightweight touch-sensitive display measuring 27 centimeters. Que users can annotate documents, by either scribbling directly on them with a finger, or using a touch-screen-based keyboard to type in notes. The two models announced today were a version with 4 gigabytes of onboard memory, retailing for $649 and the 3G-enabled version, with 8 gigabytes of memory for $799. The 8 gigabyte version should be able to store about 75,000 documents. Both weigh roughly 0.5 kilograms.
The home page on the Que features a calendar display that synches with Microsoft Exchange, and Que is working on creating wireless email and calendar. The company is partnering with Barnes and Noble to create a dedicated store, with business-oriented books and periodicals (including Technology Review) available.
To enhance the presentation of newspapers and magazines, Plastic Logic has partnered with Adobe to create the so-called truVue standard, which creates templates designed to give periodicals more of the look and feel of pages from a print issue. Subscriptions are downloaded using either WiFi or over AT&Ts 3G network.
Organic transistors can be made at much lower temperatures than those made with conventional silicon, which means it’s possible to print them on top of lightweight, flexible plastic instead of glass. The Que’s display is based on an array of one million organic transistors built on a plastic backing. This plastic array, which replaces the rigid, heavy, silicon-on-glass array in most displays, including those in other e-readers on the market, drives the pixels of the E Ink display. Though the display itself is flexible, it’s encased in rigid plastic. The advantage of the flexible plastic display is that it’s nearly unbreakable.
Plastic Logic was spun out of Cambridge University in 2000, the same year the Nobel Prize in chemistry was awarded to the three researchers who made the first electrically conductive polymers in the late 1970s (none of these researchers are associated with Plastic Logic). The first organic transistors, which performed poorly compared with silicon, were made in Japan and England in the late 1980s.
“The performance of these transistors has improved dramatically over the past 10 years,” says Henning Sirringhaus, chief scientist at Plastic Logic and professor of physics at Cambridge University. Even so, as researchers made transistors that matched or beat the performance of amorphous silicon–the material used to make the transistors that control most displays on the market–the challenge for the company was to translate these results to practical manufacturing.
Bringing organic electronics to the market has been difficult because there aren’t any companies making the equipment needed to work with them. These materials can be printed with ink jets or on giant rolls of plastic–and as long as they’re printed at a small scale, says Sirringhaus, it’s possible to get good results. Developing manufacturing-scale processes with good results took Plastic Logic many years. No equipment manufacturers sell these printing systems, says Paul Semenza, senior vice president at DisplaySearch, a market research company.
Sirringhaus says that the company uses a combination of existing and new processes to make the electronics at its factory in Dresden, Germany. “That was a big challenge for Plastic Logic,” he says. “We had some pieces of equipment we couldn’t buy.” The company does not disclose the details of its manufacturing process, but Sirringhaus says many challenges had to be overcome. Printing on plastic is challenging because it distorts during the printing process, and printed materials tend to seep into the substrate. If the material is heated too much, the plastic shrinks. Plastic Logic uses a roll-to-roll printing process to make the transistor arrays in large volumes, and at this level it’s important to ensure that all the layers of the material line up properly as they’re printed.
The Que will be an important test of the market demand for the technology. However, says Semenza, it might also be a one-off. “When one company is creating its own process from scratch, it’s very difficult to make that a mass product for two reasons: equipment producers don’t have a big enough customer base, and there is no shared learning–multiple companies going down the same path benefits everybody.”
“Many of the players in organic electronics are watching the Que carefully,” Sirringhaus says. “If it succeeds, they will have confidence that organics can work.”
Meanwhile, Plastic Logic is looking to reduce the cost of printing the electronics, and may develop flexible devices in the future. The company is also looking into new materials to further improve the performance of the transistor arrays, says Sirringhaus, and may partner with companies making color pixel arrays.
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June 11-12, 2019