Multi-functional memory elements using supramolecular self constructing interconnects – MultiSelf

Following two recent patents (owned by CNRS), we identified two promising candidates for molecular materials. We plan to take advantage of our know-how in nanomaterials with spin transition properties, with magnetic properties modified though light, pressure or temperature changes (patent 1 IPCMS-ICMCB). A new type of organic conductor, with conductivity reaching metal properties, has also been identified (patent 2 IPCMS-ICS). We propose to integrate these two materials for:
- creating a new organic spacer for spin electronics applications, showing it is possible to keep the spin memory of the charge carriers between two ferromagnetic electrodes.
- Realizing an organic conductor optimized for showing hysteretic transport properties depending on light excitations
- Combining these two properties for making a multifunctional organic device.

A key paper has been published, with a collaboration between IPCMS and ICS partners:
Nature Chemistry 4, 485-490 (2012),
Mentioned in several publication organizations (Agence France Press, CNRS News, national and local newspapers).
We show the occurrence of a supramolecular material of high conductivity, with metallic properties, allowing us to create organic interconnects at predetermined positions. The most spectacular electrical property is the small interface resistance with a metallic electrode, four orders of magnitude smaller than what is known until now.

The small interface dissipation opens the possibility for nanoscale miniaturization. This would allow multifunctional memory elements or devices based on spintronics devices, which remains a major challenge for nowadays organic electronics.

After 18 months project duration, five papers in high impact journals have been published, with three in collaboration between partners. The most important:
Light triggered self-construction of supramolecular organic nanowires as metallic interconnects ,
V. Faramarzi, F. Niess, E. Moulin, M. Maaloum, J.-F. Dayen, J.-B. Beaufrand, S. Zanettini, B. Doudin, N. Giuseppone, Nature Chemistry 4, 485-490 (2012)
One new patent application is pending

Following two recent discoveries patented by the CNRS, the goal of this project is to fabricate a new type of organic conductor, with electrical efficiency reaching those of metals, for the purpose of realizing two-terminal devices with a multifunctional non-volatile electrical state. On the one hand, we will take advantage of a recently discovered organic conductor, exhibiting spectacular electrical properties never seen previously in either conjugated polymers or small molecules assemblies (CNRS-UDS patent). Indeed, we have found that i) organic interconnects involving a firmly new class of home-made supramolecular triarylamines nanowires(STANWs) can bridge metallic electrodes through a self-fabricating process triggered by light, and that ii) outstanding transport performances of the STANWs approach those of sorted metallic carbon nanotubes, but with a much easier processability. We here propose to couple the STANWs to magnetic elements, providing the source of multi-levels and hysteretic resistance state that can be modified by external stimuli. Spin valve systems can be obtained using magnetic electrodes, whose mutual magnetic orientation results in a memory element similar to spintronics devices. On the other hand, we will take advantage of the recent progresses done on the manipulation of Spin Crossover (SCO) nanomaterials for developing optoelectronic switches (CNRS patent). Simple blending or more advanced chemical tailoring strategies will allow us to synergistically combine spin crossover elements in the conducting STANWs organics, whose structural elements will create a two-state permanent system switchable by light or temperature. The planned collaborative effort will involve four partners. The coordination is ensured by the team of B. Doudin (P1), which is internationally recognized in spin electronics and metal-organic interfaces, and which masters top-down methods to fabricate sub-microns metallic structures. The bottom-up conducting supramolecular structures will be designed by the chemistry team (headed by N. Giuseppone, P2) who has pioneered the organic and supramolecular syntheses of STANWs, and who has discovered the unique relationship that exist between their light-sensitivity, their hierarchical self-assembly features, and their electronic-transport properties. The other chemistry team involved (headed by J.-F. Letard, P3) is specialized in synthesis and studies of SCO materials, where control of bistable magnetic states can be attained by light or temperature changes. A complementary team (headed by M. Barboiu, P4) will bring its valuable expertise in the structural determination of supramolecular assemblies by X-ray crystallography. This task is crucial to supplement the understanding of the STANWs materials properties by their accurate characterization down to the atomic level.
This interdisciplinary project aims therefore at realizing optoelectronic spin valve systems, by the self-construction of highly conducting supramolecular interconnects, by trapping photoswitching nanoparticles, or by the combining the two materials between magnetic electrodes. We intend to modify the stored information by changing light, magnetic field, and temperature history of the samples, with the goal to achieve multi-responsive and multifunctional memory devices. This will provide a proof-of-principle that sub-micrometers reliable organic electronics devices bringing new functionalities can be realized.