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"Here is a more curious case:
white cats, if they have blue eyes, are almost always deaf." |
Organic semiconductors span from quantum mechanics to human disease. For example, like Schroedinger's Cat, Darwin's deaf white kitty illustrates a macro quantum phenomenon. This is strong electron-phonon coupling in potent sound-absorbing organic semiconductors such as inner-ear melanin. Likewise, these materials promise exciting new technology such as light-emitting diode ( OLED ) displays, as well as literal "printed" circuits. Finally, the conducting polymer melanin figures in (e.g.) melanoma, deafness, and Parkinson's disease.
In a series of papers in 1963, Australians DE Weiss and coworkers reported high conductivity in iodine-"doped" oxidized polypyrrole blacks. They achieved a conductivity of 1S/cm. These papers also describe the effects of iodine doping on conductivity, the conductivity type (n or p), and electron spin resonance studies on polypyrrole. Likewise, these authors noted an Australia patent application (5246/61, June 5, 1961) for conducting polypyrrole. Unfortunately, this germinal work was "lost" and went uncited by later workers.
A decade later, we also achieved a high-conductivity state, but rather differently. This was the "ON" state of a bistable switch using DOPA Melanin, a mixed copolymer of polyacetylene, polypyrrole, and polyacetylene. While well-known at the time, in a major journal (Science), and even the subject of a Nature News article, this work also went uncited.
Subsequently, Shirakawa et al described the conductive properties of iodine-doped, oxidized acetylene blacks. Based upon this (re)discovery, they received the 2000 Nobel Prize in Chemistry "For the discovery and development of conductive organic polymers".
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R. Nicolaus: "The most simple melanin can be considered the acetylene-black from which it is possible to derive all the others..... Substitution does not qualitatively influence the physical properties like conductivity, colour, EPR, which remain unaltered." from The Nature of Animal Blacks ( "acetylene-black" = polyacetylene)
I.e., melanin is a synonym for polyacetylene and vice-versa. In retrospect, melanin researchers first defined much thought "new" in this area, e.g., polyacetylene photoconductivity. Further, many tissues involved in energy transduction and/or electrical activity contain melanin, e.g., the inner ear, brain, and eye. So likely nature first discovered the interesting electrical properties of the linear-backbone polyacetylenes.
In this context, the bistable switch above is just the first of three decades of non-biological electronic devices which use some "Melanin" as an active element. This device now is in the Smithsonian institution collection .
That is, Melanin is the putative first organic semiconductor used in an active electronic device, i.e., one where an electric field modulates current flow. This was a bistable switch, the basic element of computers. Coincidentally, this means melanin is also the first organic material to show "metallic" high-conductivity. It was also the first organic semiconductor used in an energy storage ( " battery " ) application. The melanin switching curve also clearly shows negative differential resistance or *NDR", a fundamental property in molecular electronics.
This Prior Art generates an interesting question concerning the 2000 Nobel Prize in Chemistry citation. This clearly misstates the history. As I note, high conductivity in the straight-chain polymer "Blacks" had been reported at least twice before. Especially check out the work of Weiss et al. This uses oxidized iodinated polypyrrole rather than oxidized iodinated polyacetylene, but is otherwise rather similar to what nominally won the Nobel.
The Nobel foundation is a private institution and can give "The Prize" to whomever they wish. They don't have to take it back. However, a simple acknowledgement of the true history here would be proper. Otherwise, they materially misstate the history of discovery.
Here are some links.
IEEE review: The Dawn of Organic Electronics.
2000 Nobel Prize in chemistry -- " For the (third (?)) discovery and development of conductive polymers ."
Organic Active Devices: Transistors, Switches, etc.
Theory and Modeling of Organic Field-Effect Transistors (pdf)
Bell Labs: "Printing Plastic Transistors" Flexible Plastic Circuits Rubber-Stamped Circuits
IBM Organic Thin film Transistors, Review
More "Printed" circuits
Switching in Melanins A "lost" organic semiconductor device from 1974, --- the same basic active element as later devices, published in Science, then reviewed in Nature. In retrospect, names count-- the equivalent " Switching in Polyacetylenes " would have been a better title. Some pictures.
This gadget is now in the Smithsonian American Museum of History Collection
A new organic bistable switch. Much progress in 30 years-- This one also emits light.
New Molecular Switch Arrays from Hewlett-Packard
Molecular Scale Organic Switches in "Nanocell" computors
More from James Tour's Lab at Rice. Molecular switches, Nanotechnology, etc..
Sir Nevill Mott on melanins ( and thus on "polyacetylenes" in general ) " So like and yet so unlike the chalcogenide switches ". Dr. Mott won the 1977 Nobel in physics for his work on disordered materials. Present models for conduction in organic semiconductors derive from his work.
Conjugated polymers as photovoltaics
Photoconductivity in melanins.
Organic Light-Emiting-Diodes (OLED's)----
* CDT Kodak IBM Sanyo Siemens Pioneer Dupont Covion *
Miscellaneous
"Opticoelectronic Properties of Disordered Organic Semiconductors" (pdf file). A good review of conduction mechanisms in organic polymers.
Many Organic Semiconductors are Natural Products
Why electronic processes are important in disease
Britanny Spears Guide to Semiconductor Physics ( No kidding )
CalPoly Polymer Electronics Lab ( many good links_)
Intelligent Polymer Research Institute
Big
Trouble at Bell Labs: Science Fraud involving Organic Semiconductors
Peter H. Proctor, PhD, MD