The following introduction was provided by Zella King, PhD www.printedelectronics.net
What is printed electronics?
Printed electronics is the general term used to describe electronics based on semiconducting organic (i.e. carbon-based) polymers and put together using printing techniques.
Printed electronics represents a major departure from conventional manufacture of electrical and electronic components, such as silicon chips, by making possible the production of lightweight, flexible electronic devices on cheap materials such as paper or film. In effect, very thin devices can be fabricated by depositing conductive ink from a machine not dissimilar to an ink-jet printer. The use of plastic materials in conjunction with high-volume, low-cost production techniques makes it possible to produce electronic devices with radically different price, performance and functionality than conventional electronics.
An example of a simply printed electronics application. The PRISMA project used these printed RFID tags to monitor delegate movements at the Organic Electronics conference in Frankfurt, 2007.
Electronic devices and circuits can be made by printing solution-based polymer materials onto flexible or rigid surfaces. Layers with different functions are printed, one at a time and with great precision at a micro scale, onto a surface referred to as a ‘substrate’. By building up layers using additive printing processes, combined with coating and patterning processes, an electronic device is generated. The device might be a photovoltaic cell, a display that emits or reflects light, a battery or combination of these.
Innovation in printed electronics is occurring alongside wider developments in organic and thin-film electronics. It is not sensible to try to define ‘printed’, ‘plastic’ and ‘organic’ electronics as separate terms. They are different ways of describing innovations in the electronics field, but they use common materials, processes and device architectures.
- Some organic materials are made from small molecules whilst others use chains of molecules (polymers). Polymers can be solution-based, which makes it possible to print them, whilst small molecules have to be deposited using vacuum-based processing techniques. Thus in printed electronics the organic materials are made from polymers, and deposited using inkjet, screen printing or other printing techniques.
- Organic electronics involves the inclusion (either through printing or some other technique) of some organic component within a transistor or other device. Organic devices still make use of inorganic components, such as metals and silicon. Polymer Vision’s Readius product is a rollable display module, which has an organic semiconducting material (pentacene) and metal electrodes. The fully organic biodegradable device is still a long way off.
Polymer Vision’s rollable display technology, which enables mobile devices to incorporate a display larger than the handset. This is being co-developed and marketed in Italy by Telecom Italia Mobile. See http://www.polymervision.com/News-Center/Press-Releases/TelecomItaliaandPolymerVisionannouncetheCE.html
- Plastic electronics generally refers to devices built on flexible substrates, which make it possible to produce bendable electronic products, such as electronic paper. Flexible substrates offer manufacturing efficiencies in that they permit the use of reel-to-reel or reel-to-sheet production. However, flexible devices also create great production challenges because of the need for the various component layers to remain intact and in contact when the device is rolled or manipulated, exposed to heat or cold, air or water. Flexible does not necessary imply printed, however. For example, e-ink’s flex-ready electronic ink (which is used in Polymer Vision’s rollable display) is supplied as a film rather than printed.
E-ink’s Electronic Paper Display is a display that possess a paper-like high contrast appearance, ultra-low power consumption, and a thin, light form. See http://www.eink.com/technology/index.html
Why is printed electronics disruptive?
Conventional manufacture of displays and electronic components involves large expensive equipment, with silicon deposited in batch processing techniques involving multiple steps at high temperatures. Much of the material deposited is then etched off and thrown away (leaving behind the required pattern). Conventional manufacture requires huge capital investments in clean production facilities.
In contrast, printed electronics is cost-effective (since material is only deposited in required areas) and can be done with fewer steps, using continuous rather batch processes in low volumes. It does not need highly specified production environments or high temperatures. Materials and manufacturing costs will be lower, and high customisation should be feasible. Printed electronics introduces the possibility for a huge range of new applications that are lightweight, flexible and disposable.
These differences mean that printed electronics is a disruptive technology. In a market research report from 2005, NanoMarkets suggest why:
- Low cost of entry The entry costs of manufacturing in printed electronics is significantly lower than for conventional displays based on glass substrates, or semiconductors based on the etching of silicon in a solid state. New silicon plants costs $3bn, whereas printed electronics manufacturing facilities should be achievable with investment of $100ms, rather than $bns.
- New industry boundaries. If electronic circuits can be made using equipment that is similar to that used in conventional printing, companies such as Xerox and Hewlett Packard, as well as manufacturers of conventional printing equipment such as print heads, have the opportunity to enter the electronics market. In addition, companies that make materials, such as chemicals companies, see plastic electronics as an emerging opportunity.
