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Terminology: Organic semiconductors, printed electronics, or plastic electronics?Over the past few years cintelliq has had the opportunity to talk with many of the people working in the organic semiconductor industry. One of the questions that frequently arises is "Why does cintelliq use the term 'organic semiconductors' rather than 'plastic electronics' or 'printed electronics?'"cintelliq deliberately chose to use the term 'organic semiconductors' rather than using 'printed electronics' or 'plastic electronics' for two reasons:
Using 'organic semiconductors' as a term meant being able to leverage the understanding that people have of silicon semiconductors and open up the possibility of drawing analogies where appropriate. Once you have established that as a link you can then move on to say that 'organic semiconductors' can be fabricated as components - such as light-emitting diodes, transistors, memory, sensors and photovoltaic. Explaining the possibilities of 'organic semiconductors' is easier once you can draw upon widely familiar analogies from silicon. However, you do still have to remember to qualify this with the phrase ' … but transistors operate many times slower than their silicon counterparts' otherwise people may think that this technology will replace their bulky desktop PC with one that they can roll-up and put away into the desktop drawer. Plastic is misleading Adoption of either 'plastic' or 'printed' is misleading on several fronts. The use of the term 'plastic' is certainly beneficial in conjuring up images of 'flexible electronics'. However, flexibility is more a functionality of the substrate rather an inherent property of organic semiconductor devices themselves. Plastic has strong associations with polymers, and clearly there are conjugated polymers with semiconductor properties. However, while polymer-based organic semiconductors are certainly used to fabricate organic semiconductor devices they are nonetheless only one type of material that can be used. Non polymeric organic materials, in particular small molecules, are widely used in the fabrication of many organic semiconducting devices. In fact more than 90% of OLED devices being manufactured today are based on monomer rather than polymer materials. Once technology establishes a presence in the market place it is hard to displace so non-polymeric based devices are likely to be with us for a number of years to come. The best performing transistors are based on pentacene, a non-polymeric material. From my perspective to use the term 'plastic' would essentially bias the discussion to a smaller class of material and lower performing devices. It would then be necessary to find a way to introduce into the discussion a means of describing devices based on non-polymeric materials. Printing is just one deposition technique among many While the adoption of 'plastic' is limiting in terms of the materials being discussed, the use of 'printed' is just as restricting. Printing is just a means of depositing material down on to the surface of the substrate. Do consumers really care how the device that they are looking at in their mobile phone was manufactured? Depositing materials via a printing technique dictates that organic semiconductors are deposited from solution. In the majority of cases this generally means that polymeric materials are used. In contrast, monomer materials are not deposited from solution. Instead, they are deposited by a variety of thermal, vapour phase and sublimation techniques carried out in a vacuum chamber. This is the deposition approach used to manufacture 90% of the OLED displays currently on the market. So to use the word 'printed' limits the discussion to techniques such as ink-jet deposition, flexographic and screen printing. Again any other non printing technique introduced into the discussions would have to be explained. But all use organic semiconductor materials The use of the terms 'printed electronics' and 'plastic electronics' are certainly in vogue. For cintelliq the critical issue is not the material's structure or how it is deposited, but how well it performs. As we watch the industry evolve and inch its way forward to delivering its first commercial products, it is becoming clear that while companies like to define themselves in the 'printed electronics' or 'plastic electronics' space they are in reality developing products that rely on materials that are not plastics and deposition techniques that are not printing. What does tie all these companies together is the eagerness to exploit the properties of organic semiconductor materials in a growing number of ways - an eagerness that will eventually create an organic semiconductor industry. |
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