Issue link: https://iconnect007.uberflip.com/i/929192
JANUARY 2018 I DESIGN007 MAGAZINE 21 seeing is the other way, they start to go wider but they start to become more functional. Gaudion: I guess a slightly different take on printed electronics is that, rather than a pure print approach where you're looking at print- ing everything, you can certainly see parts of the process being picked away, like looking at a resist being printed on, where you've got par- ticular processes where an additive technology works well with the existing PCB manufactur- ing technology. Whereas the full prototyping, yeah, it's great for prototyping, but the lack of reinforcement's always going to be a bit of a barrier there unless there's a way of printing with reinforcement. Shaughnessy: This has been good. Is there any- thing you all would like to add? Shah: No, I think we're good for now. Shaughnessy: OK, thank you gentlemen. Gaudion: Thanks, Andy. Rick: Good talking with all of you. DESIGN007 Researchers at the Laboratory of Organic Electronics have developed the world's first complementary electro- chemical logic circuits that can function stably for long periods in water. This is a highly significant breakthrough in the development of bioelectronics. The first printable organic electrochemical transistors were presented by researchers at LiU as early as 2002, and research since then has progressed rapidly. Several organic electronic components, such as light-emitting diodes and electrochromic displays, are already commer- cially available. The dominating material used until now has been PEDOT:PSS, which is a p-type material, in which the charge carriers are holes. In order to construct effective electron components, a complementary material, n-type, is required, in which the charge carriers are electrons. In an article in Advanced Materials, Simone Fabiano, head of research in the Organic Nanoelectronics group at the Laboratory of Organic Electronics, presents, together with his colleagues, results from an n-type conducting material in which the ladder-type structure of the poly- mer backbone favours ambient stability and high current when doped. One example is BBL (polybenzimidazoben- zophenanthroline), a material often used in solar cell research. Postdoctoral researcher Hengda Sun has found a method to create thick films of the material. The thicker the film, the greater the conductivity. "We have used spray-coating to produce films up to 200 nm thick. These can reach extremely high conductivi- ties," says Simone Fabiano. The method can also be successfully used together with printed electronics across large surfaces. Hengda Sun has also shown that the circuits function for long periods, both in the presence of oxygen and water. "This may appear at first glance to be a small advance in a specialised field, but what is great about it is that it has major consequences for many applications. We can now construct complementary logic circuits – invert- ers, sensors and other components – that function in moist surroundings," says Simone Fabiano. A Major Step Forward in Organic Electronics