Tuesday, December 29, 2009

du Pont Patent Divulges New Class of Conductive Molecules for Nano-Scale Electronic Devices and Conductive Coatings


 One of a number of  new conductive molecules for nano-electronic devices created by du Pont as pictured in Figure 1 of U.S. Patent 7,638,632.

The expanding commercial interest in the generation of small nano-scale electronic devices highlights a need for the generation of a new class of conductive molecules that are functionalized for use in nano-electronic device fabrication. However, the discovery of new conductive molecules for this is fraught with difficulty.

For example, little is known about the specifics of how conductive molecules work. Additionally, it is difficult to connect conductive molecules to electrodes and even more difficult to perform conductivity measurements on single molecules. In addition to the difficulties in construction, the design of new molecules possessing useful properties is hampered by the lack of a facile method for correlating the effects of optical transitions to electronic molecular properties.

Once a structure is designed, the synthesis, purification and growth of single crystals of molecules as large as these is not easily accomplished. Typically, multistep separations are required. Finally, the coupling of different aromatic and heteroaromatic building blocks is difficult to achieve because substituted structures are prone to side reactions and long reaction times.

In U.S. Patent 7,638,632, E. I. du Pont de Nemours and Company (Wilmington, DE) inventors reveal new aromatic/heteroaromatic conducting molecules useful in nano-electronic devices and their manufacturing methods.  The molecules of the invention may additionally comprise barrier groups (--CH2, cyclic, etc.) and are versatile, allowing for the assembly of molecular components (possessing different terminal groups) in two or three dimensions. 

According to du Pont inventors Roger Harquail French, Ross Getty and Simon Percec, the conductive molecules have metallic (ohmic) and in some cases semiconductive behavior. These behaviors lend themselves to the use of these compounds both as interconnects and as actual electronic devices (e.g., switches, logic gates). In one instance, the conductive molecules are expected to be able to link nanometer scale electronic devices together permitting the fabrication of high-density electronic circuits.

 It is contemplated that it will be possible to array these compounds in a crossed arrangement, where the distance between adjacent molecules can be controlled by the potential difference between them, then the array could be used as a non-volatile memory device.

Semiconducting molecules could also find use in 3-terminal gated devices which can be used directly as switches, amplifiers or logic gates. Other possible applications include point sources for emission in field-emission display devices and as conductive inclusions in conductive coatings.

The du Pont invention relates to the design, synthesis, self-assembly and processing in the solid state of organic molecules with controllable electron conducting, semiconducting, insulating properties and/or switch characteristics derived from the presence of appropriate electron active substituents placed in selective positions of the aromatic and heteroaromatic structures.

The present compounds advance the art in that they are robust enough to allow for molecular manipulation at different temperatures and conditions. The du Pont compounds may be used in the synthesis of three-terminal devices, logic switches and other nano-electronic devices.

Additionally the compounds can function as active elements in electronic devices such as in "self assembled monolayers" (SAMs) for random-access-memory devices where data can be written, read and erased, or in sensors. Similarly, single molecules can be used as molecular wires and/or molecular switches. Wires and switches are the most basic components of memory and logic devices and components comprised of the du Pont materials will play a critical role in reducing the size of today's computer circuits.


FIG. 2 shows the x-ray crystal structure of 4-ethynyl(pyridine)-4'-ethynylphenyl-5'-nitro-1 pyridine which is another of the conductive molecules developed by du Pont for electronic nano-devices.



 

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