The functionalization of carbon nanotubes by polymers necessitates two steps, first their modification by oxidizing them or by covalently attaching small compounds to them, then the growth of the polymer chains from these anchors or their grafting onto them. In order to better control the process and the rate of functionalization, we develop polymers able to covalently react with the carbon nanotubes by their side chains in one step. We describe the synthesis of a copolymer of dodecylthiophene and its analogue bearing an aniline group at the end of the dodecyl side chain. This copolymer can functionalize single-walled carbon nanotubes (SWNTs) non-covalently and disperse more SWNTs than its hexyl analogues. UV-Vis and fluorescence spectroscopies show that in these non-covalent hybrids, the polymer forms p-stacked aggregates on the SWNTs. The non-covalent hybrids can be transformed into covalent ones by diazonium coupling. In these covalent hybrids the polymer is no longer p-stacked. According to Raman spectroscopy, the conformation of the poly(3-hexylthiophene) backbone is more ordered in the non-covalent hybrids than in the covalent ones.

Twisted bilayer graphene is a fascinating system due to the possibility of tuning the electronic and optical properties by controlling the twisting angle θ between the layers. The coupling between the Dirac cones of the two graphene layers gives rise to van Hove singularities (vHs) in the density of electronic states, whose energies vary with θ. Raman spectroscopy is a fundamental tool to study twisted bilayer graphene (TBG) systems since the Raman response is hugely enhanced when the photons are in resonance with transition between vHs and new peaks appear in the Raman spectra due to phonons within the interior of the Brillouin zone of graphene that are activated by the Moiré superlattice. It was recently shown that these new peaks can be activated by the intralayer and the interlayer electron–phonon processes. In this work we study how each one of these processes enhances the intensities of the peaks coming from the acoustic and optical phonon branches of graphene. Resonance Raman measurements, performed in many different TBG samples with θ between 4∘ and 16∘ and using several different laser excitation energies in the near-infrared (NIR) and visible ranges (1.39–2.71 eV), reveal the distinct enhancement of the different phonons of graphene by the intralayer and interlayer processes. Experimental results are nicely explained by theoretical calculations of the double-resonance Raman intensity in graphene by imposing the momentum conservation rules for the intralayer and the interlayer electron–phonon resonant conditions in TBGs. Our results show that the resonant enhancement of the Raman response in all cases is affected by the quantum interference effect and the symmetry requirements of the double resonance Raman process in graphene.

Today, most of electronic devices are based on heterostructures made by molecular beam epitaxy. The impact of van der Waals heterostructures made of 2D materials, already significant at the academic level [1], could generate a technological breakthrough in this field of electronics. Indeed, due to the weak van der Waals interlayer interactions, several materials can be assembled with a precise control of their thicknesses or their twist angles and with high quality interfaces.Recently, hybrid van der waals heterostructures, obtained by combining 2D materials and self-organized organic layers has been developed [2]. Such approach is promising to push further the versatility in terms of materials and thus a wide range of properties are expected.In this poster, we present recent results obtained on field effect transistor based on an hybrid van der Waals heterostructure made of molybdenum disulfide (MoS2) for the inorganic part and quinoidal zwitterions (QZ) for the organic part. The organic layer deposition is achieved under high vacuum, on top of the MoS2 channel of the transistor and the evolution of the transfer characteristic of the transistor is measured in situ.We observed a n-type doping and an increase of the charge carrier density of two orders of magnitudes which is comparable to the doping obtained with optimized charge transfer molecules [3][4]. These results which demonstrate the high compatibility of the QZ with MoS2 open the way for future investigations on functionalized hybrid QZ-2D materials heterostructures[1] A. K. Geim & I. V. Grigorieva Nature 499, 419–425 (2013)[2] Gobbi, M., Orgiu, E., Samorì, P., Adv. Mater. 2018, 30, 1706103.[3] Kiriya, D., Tosun, M., Zhao, P., Kang, J. S., & Javey, A. (2014). Air-Stable Surface Charge TransferDoping of MoS2 by Benzyl Viologen. Journal of the American Chemical Society, 136(22)[4] Dey, S., Matte, H. S. S. R., Shirodkar, S. N., Waghmare, U. V., & Rao, C. N. R. (2013). Charge-Transfer Interaction between Few-Layer MoS2and Tetrathiafulvalene. Chemistry - An Asian Journal,8(8)