Selective edge filling of collapsed carbon nanotubes for nanoelectronics – EdgeFiller

The project is divided into three workpackages and four transversal workpackages. The three workpackages provide the materials processing flow from raw nanotube product to prototype device. Three transversal workpackages represent the skills and techniques that will be applied to analyse, guide and control the workpackages at each step.
The first workpackage will initially aim to reproduce literature approaches to producing large collapsed carbon nanotubes from commercial MWNTs. This will include optimisation of MWNT crystallinity and purity. The second aim will be to develop new synthesis protocols from commercial MWNTs using CRPPs patented intercalation technology, in order to produce high yield, high quality collapsed CNTs.The second workpackage will adapt conventional CNT filling techniques, primarily gas-phase filling but also solution-based approaches, to filling the edges of collapsed CNTs. Different filling species will be tested including crystalline solids and molecular species (C60, TTF, TCNQ, I2, Br2). Notably we will explore asymmetric donor-acceptor edge filling via preferential molecular stacking in TTF-TCNQ and lateral electric fields in a novel custom dual-gate system. The third workpackage will integrate both pristine and edge-filled collapsed nanotubes into a prototype FET device, in order to measure their I-V response and mobility, as well as magneto-transport if appropriate. The first tranversal workpackage involves large quantum chemical simulations of different filled tube configurations, with property prediction to guide appropriate filler choice by experiment. The second transversal workpackge covers sample characterization using state-of-the-art HRTEM, holography and EELS, and resonant Raman with spatially resolved mapping, coupled to AFM. The third workpackage covers continuous lifecycle analysis (environmental impact assessment), IP protection and exploitation strategy. A final workpackage covers project management.

Project underway. For the moment:
1. We have the first promising demonstration of large collapsed nanotube production from multi-walled carbon nanotube samples, using a new patented procedure from CRPP. This production process is currently being optimized.
2. We have demonstrated, both experimentally and theoretically, that Iodine filling of single walled carbon nanotubes can cause them to collapse, at smaller diameters than is the case for unfilled tubes. This new and unexpected finding opens the door to production of narrower graphene nanoribbons and potentially use of different nanotube source material.
3. We have implemented new TGA technique using constant rate mass loss rather than temperature, allowing separation of processes occurring at very similar temperatures. We have applied this to nanotube cleaning processing in air.
4. We have developed a new theoretical approach using fingerprint functions, randomization and compression algorithms to automatically generate stable crystal filling structures inside carbon nanotubes.
5. We have now a range of theoretical and experimental proof of Iodine filling of carbon nanotubes.

To follow, as the project develops further.

At present:
1. (en préparation) Revisiting Kinetics of Thermal Oxidation of Carbonaceous Nanomaterials, Emmanuel Picheau, Ferdinand Hof, Alain Derré, Laure Noé, Marc Monthioux and Alain Pénicaud.
2. Polyiodide structures in thin single-walled carbon nanotubes: a large-scale density-functional study, D. V. Rybkovskiy, C. P. Ewels, E. D. Obraztsova, Carbon, accepted (2018).
3. Mapping the stacking interaction of Triphenyl vinylene oligomers with graphene and carbon nanotubes, A. Yaya, A. Impellizzeri, F. Massuyeau, J. –L. Duvail, P. Briddon, C. P. Ewels, Carbon, accepted (2018).
Plus 3 oral presentations and 5 posters at conferences.

EdgeFiller proposes an innovative way to create collapsed carbon nanotubes for use as a highly adaptable superior alternative to conventional graphene nanoribbons, currently proposed as a key component for future electronics. These new nanoribbons will be prepared by extracting the outer wall from large multi-walled carbon nanotubes via techniques patented by project partners. These large single-walled nanotubes (SWCNT) spontaneously collapse due to their diameter and are referred to as “dogbones” due to the cross-sectional shape they adopt, with nanometric tubular cavities at each side surrounding a central flat region.

The properties of these new hybrid materials, between graphene and SWCNTs, comes from these cavities along the edges, which will be filled with material such as salts (KI, …), molecules (C60, TCNQ, TTF, …), or metals. This allows doping (charge and/or spin) of the ribbon without introducing defects or scattering centres, a critical “roadblock” to current utilization of both graphene and SWCNTs taken separately.

This will result in a wide range of different electrical and optoelectronic behaviour. In the project, we aim to control both the conductivity this way, the p- ou n- character of charge carriers, and introduce high-mobility spin carriers.

The edge cavity filling can either be symmetry, or asymmetric (one side acceptor, the other donor), based on an innovative method we propose to develop, to create nanoribbons with strong transversal electric fields. The technique promises a cheap and easily upscalable approach resolving many of the current blockages to graphene- and nanotube-based devices. EdgeFiller brings together three world leading CNRS nanocarbon groups to develop this innovative concept, covering all fields from theoretical DFT modelling, through filled ribbon production, to a demonstration device (a prototype FET).