Electrochemically COntrolled charge/spin TRAnsport in 2D Materials – ECOTRAM

In ECOTRAM, we wish to (i) prepare Transition Metal Dichalcogenides TMDs nanosheets covalently functionalized with electroactive (one- or two-electron oxidizable or reducible) molecules, (ii) transfer efficiently these functional layers to substrates and (iii) control finely the charge/spin transport/transfer properties of these hybrid systems via a bias voltage and the thickness of sheets. A fine understanding of the TMD/molecule and substrate/TMD interfaces, an investigation of the electrical and charge/spin transport properties of the functionalized TMDs (F-TMDs) will be gained through the combination of multiple experimental techniques and theoretical modeling. Challenging outcomes of this project will be in the unprecedented elaboration of electrochemically switchable spintronics devices from functionalized TMD-modified surfaces.
We expect that the pioneering research performed in ECOTRAM will bring a considerable amount of fundamental knowledge that could have a strong impact in electronics and spintronics. More specifically, ECOTRAM will be based on the covalent attachment of electroactive molecules to TMDs, which has never been reported so far. Metallic and semiconducting MoS2 nanosheets will be explored first but particular focus will be also given to the other members of the MX2 family (with M = Mo or W and X = Se or S) TMDs which have been only marginally explored for molecular functionalization. It is anticipated that these new functionalized materials transferred to surfaces (e.g. metallic and ferromagnetic FM), will show unusual charge and spin transport properties induced by the immobilized functional group. A special focus will be placed on the tuning of some key properties of TMD (e.g. the charge and/or spin transport) by the redox state of the grafted molecule and thus the applied electrical potential.
Toward this ultimate goal, spin-dependent transport will be extended to proof-of-principle devices. Two different device geometries (horizontal vs. vertical configuration) will be realized to test the potentialities of F-TMDs for hybrid organic-2D spintronics. For both structures, it is expected that changing the redox state of the grafted molecule by the applied voltage will influence both spin-orbit coupling and the spin diffusion length of F-TMDs and thus the measurable tunnel magnetoresistance (TMR) output. Depending on both nature of the grafted electroactive molecule and the number of involved electron transfer step(s) (one or two), characteristic spin-dependent transport and TMR signatures will be generated.
Finally, capability to produce original and high-impact results will be driven by the expertise of the selected consortium gathering three partners to elaborate high-quality functional surfaces, to investigate the charge/spin transport/transfer properties of the functionalized nanomaterials and their interfaces at different scales, and to perform theoretical calculations in order to understand their electronic and charge transport/transfer properties. Also importantly, the proposed research will benefit of the growing expertise interest of the consortium in molecular spintronics and in the development of related characterization tools.