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Complex Molecular-scale Systems for NanoElectronics and NanoPlasmonics

Final Report Summary - COMOSYEL (Complex Molecular-scale Systems for NanoElectronics and NanoPlasmonics)

The COMOSYEL project (2008-13) aimed at designing complex nanometric and molecular-sized systems to process electronic or optical information from the macroscopic to the molecular scale. It proposed two specific, unconventional approaches to molecular electronics and plasmonics and the development of two multidisciplinary technical toolkits, one in bio-inspired chemistry and one in surface nanopatterning by liquid nanodispensing.
The COMOSYEL project, led by Erik DUJARDIN in CEMES CNRS (Toulouse, France), was implemented by a multidisciplinary team of up to 10 physicists and chemists. The results are being reported in high impact journals in materials science and nanosciences (Nature Materials, Scientific Reports, ACS Nano, J. Phys. Chem C,…). The main outcomes are presented in four sections.

(1) Graphene-based nanoelectronics. The general aim is to contact and pattern multi-scale electronic devices entirely produced in a single sheet of graphene with the challenge to achieve macroscopic contacts, mesoscopic interconnect architecture and molecular-size active core. All experimental technologies required for addressing molecular size graphene devices with atomic-scale structure have been developed and their integration has been demonstrated. In particular, a graphene nanopatterning technique using a gas-assisted focused electron beam has been developed to produce substrate-free devices made of sub-20 nm-wide, 0.5 micron-long graphene ribbons. The main achievement was the demonstration that functional devices comprising nanoribbons with arbitrary geometries and atomically smooth edges but without basal contamination could be reached. Atomic-scale structural characterization was completed on fully suspended graphene and the process was entirely adapted to partially suspended graphene, which made it possible to produce connected nanoribbons devices. The COMOSYEL project was thus successful in bringing graphene on the verge of integrated atomic-scale technology.

(2) Self-assembled nanoplasmonics. The optical equivalent of the graphene-based electronic addressing of molecular systems exploits the plasmonic properties of crystalline metal colloidal platelets and self-assembled nanoparticle networks. We have demonstrated, theoretically and experimentally that individual and coupled nanoparticles (spheres, rod, triangular prisms) were able to confine electromagnetic fields below 50 nm feature size and locally enhanced their intensity (PRB 2010). Moreover, we have reported for the first time the polarization-driven localization of light intensity in 2D crystalline (APL 2013) or self-assembled plasmonic architectures (J. Phys Chem C 2013) and demonstrated the direct link between non-linear luminescence and surface plasmon local density of states (SP-LDOS) for the single crystalline structures (Nature Materials 2013).
This discovery has led to the proposal of a new paradigm for optical information processing (logic gates) using the modal distribution of surface plasmons in 2D crystalline platelets. The concepts of SP modal engineering has been pushed towards ultimate lateral resolution in 10-nm wide fused nanoparticle chain networks, using swift electron excitation and energy loss spectroscopy detection (Nature Materials 2014). The SP modal engineering in crystalline systems is opening numerous opportunities that are now actively being investigated. For example, SP-LDOS also govern local heat generation in 2D gold crystals and particle assembly (ACSNano 2012) with potential implications in biosensors and actuators.

(3) Bio-inspired nanomaterials chemistry. The main achievement has been the construction of a new methodology for the synthesis of anisotropic metal colloids and their selective assembly using artificial proteins selected by two biologist collaborators by directed evolution techniques (phage display). First, using antibody libraries, we have identified arginine-rich antibodies that had a high affinity for Au(111) facets and showed that such antibodies could be used to direct the assembly of nanoparticles onto the basal (111) facets of gold prisms and effectively affect the optical properties through SP-LDOS modification upon assembly (J. Phys.Chem. C 2014). This approach was extended to more complex artificial proteins (alpha-Rep) derived from HEAT repeat proteins having a rigid morphology (3 papers in preparation). In particular, we have shown that massive assembly of gold nanoparticles is driven by the protein pair recognition after grafting them onto the particle surface. We have also shown that alphaRep has a strong morphosynthetic activity and can trigger the growth of spherical or rod-shaped gold nanoparticles.

(4) Liquid Nanodispensing. In conjunction with our method for surface-directed growth of crystalline plasmonic nanowires, we have shown that the growth could be initiated in chosen location by manipulating nanodroplets of seed precursors with our AFM-based nanodispensing technique (NADIS).