Organic electronics
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226019889
2008-07-16T13:50:27Z
Chamal N
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Reverted 1 edit by [[Special:Contributions/61.1.246.89|61.1.246.89]] identified as [[WP:VAND|vandalism]] to last revision by [[User:MER-C|MER-C]]. using [[WP:TWINKLE|TW]]
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'''Organic electronics''', or '''plastic electronics''', is a branch of [[electronics]] that deals with [[Electrical Conductor|conductive]] [[polymer]]s, [[plastics]], or [[molecule|small molecules]]. It is called '[[organic chemistry|organic]]' electronics because the polymers and small molecules are [[carbon]]-based, like the [[molecule]]s of living things. This is as opposed to traditional electronics which relies on [[inorganic chemistry|inorganic]] [[Electrical Conductor|conductor]]s such as [[copper]] or [[silicon]].
In addition to organic [[Charge transfer complexes]], technically, electrically conductive polymers are mainly derivatives of polyacetylene black (the "simplest [[melanin]]"). Examples include PA (more specificially iodine-doped trans-polyacetylene); polyaniline: PANI, when doped with a protonic acid; and poly(dioctyl-bithiophene): PDOT.
For a history of the field, see "An Overview of the First Half-Century of Molecular Electronics" by Noel S. Hush, Ann. N.Y. Acad. Sci. 1006: 1–20 (2003).
The men principally credited for the discovery and development of highly-[[conductive organic polymers]] (at least of the rigid-backbone "polyacetylene" class) are [[Alan J. Heeger]], [[Alan G. MacDiarmid]], and [[Hideki Shirakawa]], who were jointly awarded the [[Nobel Prize in Chemistry]] in [[2000]] for the 1977 discovery and development of oxidized, iodine-doped polyacetylene.
Interestingly, this prize passed over the much earlier discovery of highly-conductive organic [[Charge transfer complexes]], some of which are even superconductive. Similarly, the first demonstration of high-conductivity in the linear backbone polymers was a series of papers by Weiss ''et al'' [http://www.drproctor.com/os/weiss.htm] in 1963. These workers reported a conductivity of 1 S/cm in a similarly iodine-"doped" and oxidized [[polypyrrole]] black.
Conduction mechanisms in such materials involve resonance stabilization and delocalization of pi electrons along entire polymer backbones, as well as mobility gaps, tunneling, and [[phonon]]-assisted hopping.<ref>McGinness, J.E., Mobility gaps: a mechanism for band gaps in melanins Science. 1972 Sep 8;177(52):896-7</ref>
[[Image:Gadget128.JPG|frame|right|Melanin voltage-controlled switch, an "active" organic polymer electronic device from 1974. Now in the Smithsonian.]]
Conductive polymers are lighter, more flexible, and less expensive than inorganic conductors. This makes them a desirable alternative in many applications. It also creates the possibility of new applications that would be impossible using copper or silicon.
New applications include [[smart windows]] and [[electronic paper]]. Conductive polymers are expected to play an important role in the emerging science of [[molecular computer]]s.
In general organic conductive polymers have a higher [[resistor|resistance]] and therefore conduct electricity poorly and inefficiently, as compared to inorganic conductors. Researchers currently are exploring ways of "doping" organic semiconductors, like melanin, with relatively small amounts of conductive metals to boost conductivity. However, for many applications, inorganic conductors will remain the only viable option.
==Organic electronic devices==
A 1972 paper in the journal Science <ref>McGinness, J.E., Mobility gaps: a mechanism for band gaps in melanins Science. 1972 Sep 8;177(52):896-7</ref> proposed a model for electronic conduction in the [[melanin]]s. Historically, melanin is another name for the various oxidized [[polyacetylene]], [[polyaniline]], and [[Polypyrrole]] "blacks" and their mixed copolymers, all commonly-used in present day organic electronic devices. E.g., some fungal melanins are pure polyacetylene. This model drew upon the theories of [[Neville Mott]] and others on conduction in disordered materials. Subsequently, in 1974, the same workers at the Physics Department of [[The University of Texas M. D. Anderson Cancer Center]] [http://www.organicmetals.com/amorphous.htm reported] an organic electronic device, a voltage-controlled switch <ref>Science, vol 183, 853-855 (1974) </ref>
Their material also incidentally demonstrated "[[negative differential resistance]]", now a hall-mark of such materials. A contemporary [http://www.organicmetals.com/naturea.htm news article] in the journal ''Nature'' noted this materials "strikingly high conductivity'. These researchers further patented batteries, etc. using organic semiconductive materials. Their original "gadget" is now in the Smithsonian's collection of early electronic devices.
This work, like that the decade-earlier report of high-conductivity in a polypyrrole[http://www.drproctor.com/os/weisspaper.pdf], was "too early" <ref> "An Overview of the First Half-Century of Molecular Electronics" by Noel S. Hush, Ann. N.Y. Acad. Sci. 1006: 1–20 (2003).</ref> and went unrecognized outside of pigment cell research until recently. At the time, few except cancer research institutes were interested in the electronic properties of such polymers, which are applicable to the treatment of [[melanoma]].
==In the news==
* [http://news.bbc.co.uk/1/hi/business/6227575.stm BBC News - UK firm Plastic Logic has said it will build the world's first factory to produce plastic electronic chips.]
==See also==
*[[Melanin]]
*[[Organic semiconductor]]
*[[Printed electronics]]
*[[Organic LED]]
==References==
{{reflist}}
==External links==
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* [http://nn.physics.auth.gr/isfoe International Symposium on Flexible Organic Electronics, 9-11 July 2008, Halkidiki, Greece]
* [http://ltfn.physics.auth.gr Lab for Thin Films Nanosystems & Nanometrology (LTFN), Thessaloniki, Greece]
* [http://web.abo.fi/fak/mnf/fysik/mole/molehome.htm Organic Electronics Group, Åbo Akademi University, Finland]
* [http://www.ifm.liu.se/biorgel Olle Inganas research group at Linkoping university]
* [http://www.idtechex.com/printelecreview/en/index.asp News on organic and printed electronics]
* [http://www.cintelliq.com/newsletter.htm News on organic semiconductors, organic electronics and printed electronics]
* [http://organics.eecs.berkeley.edu/index.htm Organic electronics group in UC Berkeley]
* [http://www.orgel.itn.liu.se Organic electronics group at Linköping University, Sweden]
* [http://www.physics.nus.edu.sg/~ondl/ Organic Nano Device Laboratory at National University of Singapore]
* [http://www.phys.umu.se/opeg/ The Organic Photonics and Electronics Group at Umea University, Sweden]
* [http://www.oe-a.org Organic Electronics Association]
[[Category:Electronics]]