There was a time when cars were going to be made entirely of plastic. There seemed to be no limit to the capabilities of the new wonder material but it was a triumph of hope over reality.
Plastics have been widely used in cars of course but state of the art cars these days are increasingly electric and the traction batteries and motors, and much else besides, depend heavily on the technologies of metals and ceramics.
In another glamorous new sector - printed electronics - the special interest groups and the government departments funding research still act as if it is all going plastic. They heavily fund the magic of organics for the next generation of almost everything electronic and electric.
Collaboration and balance
The truth is more prosaic. What matters is finding the best way of doing things and that means inorganic and composite materials, with a place for purely organic materials as well. This is more than an academic point to make because researchers and industrial organisations with the vital skills in inorganics and composites are sometimes being deterred from participating or at least get left with the rump of the funding.
Taking the balanced view
One antidote is the IDTechEx event Printed Electronics Europe (www.IDTechEx.com/peEUROPE) in Dresden Germany on 13-14 April. With no specific bias, the organisers have simply sought the most exciting advances and applications in this new world of stretchable, invisible, morphable, tightly rollable, edible and other previously impossible electronics. The result is that, alongside the newly printable organic displays, transistors and the like are inorganic and composite ones sometimes with parameters that are one hundred times better.
Record low cost, high volume
How do we get volumes higher and costs lower than conventional electronics can ever achieve, so we can enjoy such things as disposable electronic packaging and labels? One answer is replacing the silicon chip with printed silicon. Indeed the only RFID labels meeting the world's favourite RFID standard with about 1000 transistors in a tiny area have been made this way. Nanogram, of the USA, which speaks at the event, is now printing those on polyimide film, for example, and the University of Cape Town in South Africa also presents new progress with this option. Printed zinc sulphide with manganese gives us light emitting AC electroluminescent displays that are rollable and conformal and these continue to take market share. Start up Lumoza, speaking at the event, produces printed flexible computer animations on flexible surfaces.
New flexible inorganic and composite batteries
Like those car batteries, printed flexible batteries are usually inorganic, relying on lithium, manganese or, in the case of a new battery being announced by the University of Science in Uppsala Sweden at the conference -salt and paper. On the other hand, using both organic and inorganic expertise led to the Advanced Materials Innovation Centre in Japan creating a printed lithium polymer flexible battery this year.
Base metals, fine metals, oxides and mixtures
Impressive progress and new applications of flexible copper indium gallium diselenide photovoltaics is covered by EMPA Switzerland, Solarion Germany and others. The composite Dye Sensitised Solar Cells DSSC, based on titanium dioxide, are covered by Dyesol Australia, University of Jaume in Spain, Konkuk University Korea etc - the latter covering organic PV as well. IBM has recently announced that it has built a solar cell where the key layer, that absorbs most of the light for conversion into electricity, is made entirely of readily-available elements - that set a new world record for efficiency and holds potential for enabling solar cell technology to produce more energy at a lower cost. Comprised of copper, tin, zinc, sulphur, and/or selenium, the cell's power conversion demonstrates an efficiency of 9.6 percent - 40 percent higher than the value previously attained for this set of materials and apparently ahead of organics.
Lower cost, tightly rollable transparent electrodes
Most flexible displays and photovoltaics uses transparent electrodes. New inorganic and organic transparent electrodes are coming along to replace indium tin oxide, today's staple, with something lower cost and more tightly rollable. The conference has one inorganic metal oxide option and one organic option to announce. For balance, inorganic, organic and carbon nanotube transistors are each described by several lecturers and even the possibilities with graphene carbon are clarified. The disparate market needs mean that there will be several winners here.
From baby ointment, paint whitener and glass to superlative electronics
Humble compounds such as the zinc oxide in baby ointment are now modified as semiconducting ink to make the only transparent, high current, flexible printed transistors. For example, this year, presenter Samsung of Korea has chosen zinc oxide based transistors for its flexible AMOLED backplane display drivers because printed organic transistors cannot handle the current.
Titanium dioxide used as paint whitener is modified for the DSSC photovoltaics we mentioned but it is also the basis of the printed memristor covered by the National Institutes of Standards and Technology in the USA. This is an exciting new flexible printed component that can reduce the number of transistors needed in a circuit and provide advanced rollable, non-volatile memory. Nanopool GmbH in Germany has just announced a spray-on glass based on silicon dioxide that is 500 times thinner than a human hair and will be useful in the new electronics, not least for protecting against moisture and dirt. Ever finer metal patterning gives us nantennas connected to the new printed metal oxide ballistic diodes in trillions of pairs to turn sunshine into electricity. Metamaterials based on similar miniature metal patterning, bend light using quantum effects. This is leading to previously impossible printed components and circuits being printed. MaTox of the USA cover flexible micropatterning. Two speakers cover new forms of new printable copper.
Gallium and indium are behind the morphable antennas newly announced by North Carolina State University. Modern antennas are made from copper or other metals, but there are limitations to how far they can be bent - and how often - before they break completely. NC State scientists have created antennas using an alloy that "can be bent, stretched, cut and twisted - and will return to its original shape," says Dr. Michael Dickey, assistant professor of chemical and biomolecular engineering at NC State and co-author of the research.
The best way forward
Unusually for conferences on the new electronics, Printed Electronics Europe (www.IDTechEx.com/peEUROPE) presents a similar number of advances in inorganic, organic and composite printed materials. Raghu Das CEO of analysts IDTechEx, organisers of the event, says, "We see that situation pertaining for at least the next ten years." It is much the same as cars really.