CONTEXT

Organic electronics, a branch of electronics dealing with organic conductors, is in need of higher performance materials because the current ones do not offer metallic conductivity. Moreover, the typical high resistance of classical conjugated polymers at the metal/organic interface prevents the downscaling of the devices, impeding realization of submicrons-scale circuit elements.

TECHNICAL DESCRIPTION

In the present work, the inventors first found out that some modified triarylamine derivatives self-assemble in solution upon an electromagnetic radiation leading to highly defined supramolecular fibers that stabilize electronic charges (publication Angew. Chem. Int. Ed. 2010, 49, 6974-6978).

The inventors then found that these self-assembled fibers show very high ohmic conductivity, with an extremely low contact resistance with the metal, and a trully metallic behavior (that is a monotonic decrease in resistance with temperature). These measurements are based on the deposit of a triarylamine solution on a device, which comprises a substrate and two surfaces where an electric potential is applied, and by the subsequent light irradiation of the said solution.

The French application protects the process of a) depositing a triarylamine solution into the device and b) the metallic conductivity resulting from the radiation-promoted self-assembly. As for the US provisionnal application, it also protects c) the forming of the self-assembly as a consequence of the radiation and d) the structures of the molecules.

DEVELOPMENT STAGE

• Electromagnetic radiation promoted self-assemblies;
• Prototype of radiation promoted self-assembly used as conductor in a device comprising a substrate and two surfaces where an electric potential is applied.

BENEFITS

The process of deposing a triarylamine solution and forming conductive self-assembly offers numerous advantages:

• Simple and accurate deposit ;
• Metallic conductivity ;
• Low interface resistance at metal/organic interface <10^-2 Ω.cm ;
• Radial orientation of the fibers between surfaces ;
• Irreversible if solvent withdrawn ;
• Reversible process if heated in presence still of solvent ;
• Long term stability ;
• No degradation of performance when exposed to humidity and oxygen;
• Low toxicity.

INDUSTRIAL APPLICATIONS

The main applications concern organic electronics where such conductive supramolecular self-assemblies, because of their simplicity of fabrication and processability, and because of their conductivity properties, can definitely overpass current conductive materials.

First, these materials can be used as conductors for organic light-emitting diodes (OLEDs), as organic field-effect transistors (OFETs), components in organic solar cells (OSCs), but also envisaged for other implementations in electronic papers, sensors, memories, bioelectronic applications.

Second, due to their low contact resistance, the devices can be downscaled at the bottom of nanoelectronic devices.

Finally, the process of depositing and activating the triarylamine solution onto the device can be used for the light-directed patterning (formation) and/or soldering (repairing) of electronic nanocircuits.

Publication: Angew. Chem. Int. Ed. 2010, 49, 6974-6978; Nature Chemistry 4, 485–490 (2012); Nanoscale, 2012,4, 6748-6751; Adv Mater. 2012 Sep 12

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