bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Coupled Quantum Defects of DNA Functionalized Carbon Nanotubes
Authors: Htoon Han
Published: May 2020

Single wall carbon nanotubes (SWCNTs) with sp3 defects created via covalent bonding of organic functional groups are rapidly emerging as a new material system for chemistry, physics, material science, engineering and quantum technologies. They are often referred to as “organic color centers” as they can mimic quantum mechanical properties of solid-state color centers.1 Their unique properties include highly enhanced molecularly wavelength-tunable fluorescence and room temperature single photon generation with 99% single photon purity at 1.55 µm telecommunication wavelength.2 To date, diazonium chemistry has been the chemists’ tool of the choice for creating sp3 defects sparsely distributed at random positions along the sidewall of SWCNTs. While such distribution is ideally suited for single photon generation, an ability to incorporate multiple coupled quantum defects in a well-defined spatial pattern is highly desirable for more sophisticated quantum information science applications involving entanglement. Recent discovery of covalently functionalizing SWCNTs with single-stranded DNA (ssDNA)3 open a possible path toward achieving this goal. In this process, SWCNTs form covalent bonds to the guanine nucleotides when aqueous suspensions of SWCNTs coated with ssDNA are exposed to singlet oxygen. As a result, creating a regular array of covalent defect with spacing defined by the ssDNA sequence become a possibility. To further explore this exciting possibility, we investigated intrinsic PL emission properties of ssDNA functionalized SWCNTs through low temperature single tube PL spectroscopy. In contrast to individual aryl functionalized SWCNTs that usually emit a single sharp isolated PL peaks, multiple PL peaks with their emission wavelengths varying from 1050 to 1300 nm were observed from individual ssDNA functinalized SWCNTs. We further conducted 2nd order photon correlation (g(2)) and cross-correlation experiments to investigate their quantum light emission properties. We observed photon anti-bunching behavior when an individual PL emission peak is spectrally isolated indicating that ssDNA functionalization creates a series of quantum defects along the length of SWCNTs. Interestingly, when the g(2) experiment is performed on combined emission of multiple (2—4) PL peaks, an incomplete antibunching with g(2)(0) values in the range of 0.2-0.4 is observed. Because these values are significantly smaller than g(2)(0) values estimated for 2-4 independent quantum emitters (0.5-0.75), we interpret that the series of defects created via ssDNA functionalization are coupled. Our photon cross-correlation experiment performed between two emission peaks of the group also reveal evidence of coupling.

1 Srinivasan, K. & Zheng, M. Nat. Photon.
11, 535 (2017).

2 Brozena, A.H., Kim, M., Powell, L.R. & Wang, Y. Nat. Rev. Chem.
3, 375-392 (2019).

3 Zheng, Y., Bachilo, S. M., Weisman, R. B. ACS Nano, 13, 8222 (2019)
(Invited) Ultrasonication-Induced Inner Shell Extraction from Double‐Wall Carbon Nanotubes: Characterisation By Ultracentrifugation and in Situ Raman and Fluorescence-Excitation Spectroscopy
Authors: Wenseleers Wim , Erkens Maksiem , Cambré Sofie , Flahaut Emmanuel
Published: May 2020

We show that ultrasonication readily extracts inner tubes from double-wall carbon nanotubes (DWCNT), and characterize the process by density gradient ultracentrifugation (DGU) combined with in situ spectroscopic characterization in the density gradient. Our observations also cast new light on the question whether or not the inner tubes of DWCNTs fluoresce, which has been the subject of a long-standing debate, even though single‐DWCNT experiments have already shown drastic PL‐quenching for the inner CNT [1]. Indeed, in previous studies to characterise the PL from DWCNTs, they were typically solubilised using sonication, while here we see that upon sonication, the extraction of the inner tubes from the DWCNTs leads to much more efficiently fluorescing SWCNTs. First, the DWCNTs were purified from SWCNTs and bundles using density gradient ultracentrifugation (DGU). Then, sonication is applied, after which the extracted inner tubes were separated from the DWCNTs by DGU and characterised by in situ resonant Raman and PL‐spectroscopy as a function of height in the centrifuge tube [2]. These subsequent in situ DGU experiments unambiguously prove the extraction of inner SWCNTs from DWCNTs, even by very brief sonication, and sonication-time-dependent measurements show that the process quickly saturates.

[1] D. Levshov, R. Parret, H.-N. Tran, T. Michel, T.T. Cao, V.C. Nguyen, R. Arenal, V.N. Popov, S.B. Rochal, J.-L. Sauvajol, A.-A. Zahab, M. Paillet, Phys. Rev. B
96, 195410 (2017).

[2] S. Cambré, P. Muyshondt, R. Federicci, W. Wenseleers, Nanoscale
7, 20015 (2015).
(Invited) DNA-Wrapped Carbon Nanotubes Via Methanol-Aided Replacement of Surfactants
Authors: Yang Yoona , Sharma Arjun , Noetinger Guillaume , Zheng Ming , Jagota Anand
Published: May 2020

DNA/Single-wall carbon nanotube (SWCNT) hybrids have attracted interest due to their ability for SWCNT separation and their use as promising agents in biosensing and bioimaging applications. In order to perform such SWCNT separation and for application development, special DNA sequences are needed that have an ability to recognize specific chiral SWCNT. So far, sequence screening has relied on various methods which are costly and time-consuming. Recently, a simple new and rapid way to produce DNA-SWCNT hybrids was reported using replacement of surfactant on SWCNT by DNA, aided by methanol. However, little is known about the nature of the exchange mechanism. Here, we investigated the process of replacing surfactant by DNA. We propose a mechanistic model to analyze and extract the activation energy of the exchange process. We find that some recognition sequences have significantly different activation energy for different species of SWCNT, while some sequences do not. Hybrids obtained via the surfactant replacement route were compared with those obtained by direct sonication using ATP separation and photoluminescence (PL) spectroscopy. We found that for some sequences, hybrids obtained by the two routes show the same separability as well as PL spectra, but for some sequences do not. Thus, it appears that the replacement process does not always produce the same structure of DNA-SWCNT as produced by traditional direct sonication. Taking all the experimental findings into consideration, we propose a free energy diagram for DNA-SWCNT hybrid formation by surfactant replacement.
Exploring the Impact of Counterion Chemistry on Carrier Doping of Carbon Nanotubes
Authors: Ferguson Andrew John , Blackburn Jeffrey L.
Published: May 2020

Semiconducting single-walled carbon nanotubes (s-SWCNT) are viewed as a promising candidate for optical, electronic, and energy conversion applications. Often the performance of carbon nanotubes in these applications is dependent on being able to control the interplay between their optical and electronic properties. One strategy toward achieving this control is tuning the position of the Fermi level through chemical doping to inject charge carriers into the electronic density of states.

We have previously demonstrated that p-type doping using the one-electron oxidant, triethyloxonium hexachloroantimonate (OA) results in very efficient injection of free carriers into near-monochiral s-SWCNT networks. Here we build on our previous work by employing a series of charge-transfer dopants based on boron clusters appended with various organic moieties that control the redox properties of the dopant. These dopants are unique, since their chemical structure means that the electron that is extracted from the nanotube is localized on the boron cluster and spatially separated from hole density injected into the carbon nanotube. We explore the charge-transfer doping process using these boron-cluster dopants, the resulting charge-carrier transport properties of the doped s-SWCNT networks, and make a comparison to networks doped using either OA or 2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ). We will present spectroscopic and bulk conductivity measurements of charge-transport in high-mobility s-SWCNT networks and will discuss the impact that the chemistry and structure of the dopant counterion has on charge transport and the implications for electronic devices comprised of these tailored s-SWCNT networks.
(Invited) Charge-Localization in Doped Semiconducting Carbon Nanotubes Revealed By IR- and EPR Spectroscopy
Authors: Eckstein Klaus H , Auth Michael , Oberndorfer Florian , Schoeppler Friedrich , Sperlich Andreas , Dyakonov Vladimir , Hertel Tobias
Published: May 2020

IR and EPR spectroscopic investigations of redox- p-doped semiconducting (6,5) single-wall carbon nanotubes (s-SWNTs) were used to study carrier localization and delocalization from low- up to degenerate doping levels. At low carrier concentrations, the analysis of IR-intraband transitions as well as the appearance of a doping-induced vibrational D-band anti-resonance, point to charge-localization on the few nm length-scale. Moreover, the rise of a spin 1/2 signal in EPR closely tracks the increase of the doping level, supporting the notion of charge-localization at low carrier concentrations. At doping levels exceeding 0.1 nm-1, EPR data as well as intra- and D-band absorption in the IR point to antiferromagnetic coupling between surplus charge carriers becoming dominant. These results are expected to be relevant for field- or redox-chemical doping of s-SWNTs in any polarizable, heterogeneous environment.
(Invited) Photoluminescent Property Modulation of Locally Functionalized Single-Walled Carbon Nanotubes Based on Molecular Factors in Bis-Aryl Functionalization
Authors: Shiraki Tomohiro , Yu Boda , Niidome Yoshiaki , Fujigaya Tsuyohiko
Published: May 2020

Photoluminescence (PL) in the near infrared (NIR) region is applicable to bioimaging and telecommunication devices. Single-walled carbon nanotubes (SWNTs) with semiconducting features show NIR PL whose properties are governed by photogenerated excitons in the one-dimensional nanostructures. Defect doping to SWNTs is gathering great attentions due to enhance the contribution of the excitons to PL. The doped sites work as emissive sites with narrower bandgaps and exciton trapping features. As a result, additional PL (E
11*) with red-shifted wavelengths and enhanced quantum yields newly appears compared to original PL (E
11) of pristine SWNTs.[1-9]

Local chemical modification for the defect creation achieves molecular functionalization of the defect-doped sites of the tubes, providing locally functionalized SWNTs (lf-SWNTs). They are found to show PL modulation based on the functionalized molecules. Here, we report bis-aryl functionalization for proximal defect doping of lf-SWNTs, in which molecular structure effects of bis-aryl diazonium modifiers and microenvironmental effects of the doped sites are discussed.

Bis-arydiazonium salts (bAs) that had two reactive aryldiazonium groups connected with a methylene linker were synthesized and reacted with solubilized SWNTs for local functionalization. For PL wavelength modulation, the linker effects were examined by changing the connected positions on the aryl groups (pbAs for para and mbAs for meta) and the length of methylene chains.[5,8] In PL spectra of the synthesized lf-SWNTs (lf-SWNTs-pbA and lf-SWNTs-mbA), peaks appearing over 1200 nm (E
11
2*) changed sensitively depending on the chemical structures of bAs. In addition, the E
11
2* PL showed unique wavelength shifting behaviors by microenvironment changes using various organic solvents, which was different from those of E
11 PL and E
11* PL.[9]

Thus, bis-aryl functionalization in lf-SWNTs creates the doped sites whose properties are different from typical doped sites showing E
11* PL and would be useful for fundamental understanding of this material and developing modulation techniques of the longer wavelength NIR PL.

[1] B. Weisman et al. Science, 330, 1656 (2010). [2] Y. Miyauchi et al. Nat. Photon., 7, 715 (2013). [3] Y. Wang et al. J. Am. Chem. Soc., 138, 6878 (2016). [4] S. Doorn et al. Nat. Photon., 11, 577 (2017). [5] T. Shiraki et al. Sci. Rep., 6, 28393 (2016). [6] Y. Maeda et al. Nanoscale, 8, 16916 (2016) [7] T. Shiraki et al. Chem. Commun., 53, 12544 (2017). [8] T. Shiraki et al. Chem. Lett., 48, 791 (2019). [9] T. Shiraki et al. Chem. Commun., 55, 3662 (2019).

Figure 1
(Invited) Nanotube-Based Nanohybrids Made of Dyes Encapsulated inside Nanotubes
Authors: Martel Richard
Published: May 2020

The inner and outer surfaces of a nanotube made of either carbon or boron nitride materials can be functionalized to tailor the chemical and optical properties of the assembly. Our studies on the optical properties of dyes encapsulated in nanotubes show for instance enhancement effects in both Raman and fluorescence spectroscopies, which are interesting for making optical nanoprobes for bio-imaging. Chemical functionalization of the outer wall has also been effective in promoting specific chemical interaction with a host, such as a biomarker. Here we will more specifically review our recent progress on the nanotube-based nanohybrids and focus the discussion on the case of the boron-nitride nanotubes for optical imaging. More particularly, we have made advances towards the preparation of boron-nitride nanotube nanohybrids for fluorescence imaging with visible and near-infrared emissions. Recent results on the outer functionalization to work more effectively in biological media and on the aggregation effects of encapsulated dyes probed optically in different conditions will be discussed.

This work was done in collaboration with E. Gaufrès, C. Allard, S. K. Mal, N. Tang, R. Nascimento, C. David, L. Durate, Louis Gaboury and S. Blais-Ouellette
Terahertz Transmission Limiters Using Randomly Oriented Carbon Nanotubes Network Near Percolation Threshold
Authors: Park Junsung , Kim Jin Ho , Xu Jimmy , Shur Michael
Published: May 2020

We demonstrated a dramatic reduction in the sub-terahertz (sub-THz) transmittance and enhancement in the conductance of the carbon nanotube (CNT) mats at high radiation intensities near the percolation threshold, i.e. at the CNT concentrations where the mat conductivity as a function of the CNT concentration sharply increases. The CNT mat conductivity near the percolation point is determined by the electron (or hole for p-type CNTs) tunneling between the adjacent nanotubes. The symmetry of CNT contacts is broken by the differences in the positions and the sizes and types of the contacting CNTs enabling the rectification of the THz or sub-THz radiation impinging on the CNT mats. As the consequence of such rectification, the tunneling barrier shape changes to a more triangular share enhance the CNT mat AC conductivity and decrease transmission. One application of this effect is films preventing damage to sensitive THz and sub-THz detectors (such as Schottky diodes or TeraFETs) by limiting the maximum power impinging on the detectors. Since the shape of the tunneling barriers is strongly affected by ambience and/or substrate monitoring limiting CNT transmission near the percolation point transmission as function of intensity, temperature, and frequency could be used for humidity, temperature, gas exposure, strain, and multiple sensors of external stimuli. The nanoscale of CNT contacts and gaps enables high speed THz responses.
(Invited) Carbon Dots – from Imaging to Green Energy Applications
Authors: Naccache Rafik
Published: May 2020

In recent years, nanomaterials (defined as materials < 100 nm in a single dimension) have garnered a significant interest for the development of novel applications in the physical and life sciences. One such class of nanomaterials are carbon dots, a relatively new member in the carbon allotrope family, which possesses versatile optical properties rendering it attractive for sensing, catalysis, bioimaging and drug delivery applications, to name a few. Their ultra-compact size, low cytotoxicity, resistance to photo-bleaching/blinking and tunable photoluminescence, combined with simple, environmentally-friendly and low-cost synthesis, makes them ideal candidates for study. We synthesize carbon dots via bottom-up synthesis methods, with simple organic precursors (e.g. citric acid) as the carbon source. We passivate the surface of our carbon dots to achieve high fluorescence quantum yields. Moreover, our work focuses on trying to elucidate the fluorescence mechanisms in carbon dots, which remain a subject of debate. Finally, we exploit their optical properties in order to design multifunctional materials as chiral, pH or temperature sensors, as well as heterogeneous catalysts for green energy applications.
(Invited) Optical Properties of Graphene Nanoribbons and Quantum Dots
Authors: Liu Thomas , Zhao Shen , Rondin Loïc , Chassagneux Yannick , Campidelli Stephane , Voisin Christophe , Lauret Jean-Sébastien
Published: May 2020

Graphene is a key material for nanoelectronics. Nevertheless, its zero gap makes it unsuitable for applications needing semiconductors with sizeable energy gaps. One way to open a gap in graphene is to use size reduction effects. The reduction of one dimension leads to carbon nanotubes and graphene nanoribbons that are 1D carbon nanostructures. Reducing one more dimension leads to 0D graphene quantum dots. The optical properties of carbon nanotubes have been investigated for approximately 20 years, while the study of graphene quantum dots and nanoribbons is at its infancy.

Among potential application of these sp2 carbon nanostructures, the use of graphene nanoribbons and quantum dots as light emitters attracts a lot of attention. Here, I will present our recent results on the optical properties of graphene quantum dots synthesized by bottom-up chemistry [1].

References

[1] S. Zhao et al, Nature Communications 9, 3470 (2018)
(Invited) Electrochemical Applications of Carbon Nanotube Microfibers
Authors: Poulin Philippe
Published: May 2020

We present fiber electrodes which are made of assembled carbon nanotubes (CNTs). The present fibers are highly porous and of a few tens of microns in diameter. They exhibit promising performances as microelectrodes for enzymatic bio-fuel cells (BFCs), or electromechanical actuators. The electrodes are manufactured by a fiber wet spinning process in which CNTs and bilirubin oxidase (BOD) are combined without any red-ox mediator or binder. BOD allows the reduction of oxygen at potentials suitable for uses in physiological conditions. Moreover, because of their small dimensions and electronic properties, CNT microelectrodes overcome poor electron transfer and mass transport limitations. In addition to applications in enzymatic BFCs, CNT fibers can also be woven and used under the form of mats for microbial BFC applications. The mats display large and small pores which respectively favor colonization by bacteria and high specific surface area. Last, we will show that CNT microfibers can be used as miniaturized electromechanical actuators. Indeed, CNT assemblies deform in response to charge injection and electrostatic phenomena. Nevertheless, as observed in other CNT based actuators, raw CNT fibers suffer from stress relaxation due to the sliding of neighboring CNTs. In order to overcome this limitation, we have developed a process in which a small amount of polymer binder is included within the fibers during the spinning process. The presence of the binder results in a significant reduction of stress relaxation. From a general point of view, the present results open routes towards the use of CNT fiber electrodes to power or actuate implanted biomedical micro-devices.
(Invited) Dynamics of Nitrogen Functionalization of Graphene
Authors: Côté Michel , Malenfant-Thuot Olivier
Published: May 2020

For graphene to be used eﬃciently in scientific and technological applications, its electronic properties need to be tailored to suit precise demands. The formation of a forbidden energy gap or the modification of the Fermi energy is achievable with functionalization techniques that simultaneously leave most of the atomic structure of graphene unchanged. Nitrogen functionalization is one of the most promising and studied types of treatment, in large part due to the proximity between carbon and nitrogen in the periodic table. It has already produced promising experimental results in the fields of high-sensibility biodetectors, field-eﬀect transistors, solar cells, and supercapacitors, among others.

To further understand this functionalization, we have performed an ab initio electronic structure study of different doping configurations and functionalization dynamics of nitrogen treatments of graphene. In particular, we have study the effect of simulation cell size used to carry our these calculations. We found that the inclusion of the special point K of the first Brillouin Zone in the momentum space sampling lowers formation energy results and should not be overlooked. Nudged Elastic Band calculations were also completed to study diﬀerent incorporation mechanisms from an adsorbed state to in-plane doping. In the presence of native defects, low barriers of 0.55 eV and 0.46 eV were obtained. When no defects are present, much larger barriers between 3.70 eV to 4.38 eV were found, which suggests an external source of energy is required to complete the incorporation.

In the second part of this presentation, we will report our result of using machine learning models to predict higher-level quantities. The goal of this work is to study the dependence of the Raman response of nitrogen functionalization of graphene. To simulate such a response, very large simulation cells need to be considered that would be out of reach for ab initio techniques, hence the use of machine learning methods to assist in the evaluation of the properties. Machine learning methods are now used more and more as a substitute for density functional theory calculations due to their low computational costs. However, in more advanced cases, relevant datasets are not always available, and the effort that would be necessary to generate the needed data suppress the advantages of using machine learning to speed up the calculations. Furthermore, the process of training a reliable model is not trivial and can also be expensive which should encourage the usage and diffusion of portable trained models.

Figure 1
(Invited) Charge Carrier Transport and Separation in Pristine and Nitrogen-Doped Graphene Nanowiggle Heterostructures
Authors: Lherbier Aurélien , Liang Liangbo , Charlier Jean-Christophe , Meunier Vincent
Published: May 2020

Electronic structure methods are combined into a multiscale framework to investigate the electronic transport properties of recently synthesized pristine and nitrogen-doped graphene nanowiggles and their heterojunctions deposited on a substrate. Real-space Kubo-Greenwood transport calculations reveal that charge carrier mobilities reach values up to 1000 cm²/Vs as long as the amount of substrate impurities is sufficiently low. Owing to their type-II band alignment, atomically precise heterostructures between pristine and N-doped graphene nanowiggles are predicted to be excellent candidates for charge carrier separation devices with potential in photoelectric and photocatalytic water splitting applications.
(Invited) Scanning Gate Imaging of Charge Transport in Graphene Nanodevices
Authors: Brun Boris , Moreau Nicolas , Somanchi Sowmya , Nguyen Viet-Hung , Watanabe K , Taniguchi T , Stampfer Christoph , Charlier Jean-Christophe , Hackens Benoit
Published: May 2020

Quantum transport in nanodevices is usually probed thanks to measurements of the electrical resistance or conductance, which lack the spatial resolution necessary to probe local-scale electron behavior. Here, we will discuss how to get real-space local information on peculiar quantum transport phenomena inside graphene constrictions. The results were obtained using low temperature scanning gate microscopy (SGM), which consists in mapping the electrical conductance of a device as an electrically-biased sharp metallic tip scans in its vicinity [1].

If the tip-induced perturbation is relatively small, SGM is an imaging technique giving access to the local density of states inside mesoscopic devices [2]. Here, we will focus on the regime of large tip-induced perturbation. This regime is particularly interesting in the case of graphene: depending on tip voltage and tip-sample distance, one can tune the shape, size, and smoothness of the moving scattering region associated with the tip, and eventually create a moving circular pn-junction within the device. We use this moving pn-junction to probe peculiar aspects of relativistic charge carrier dynamics within graphene devices: Klein tunnelling and current focusing and defocusing [3], Fabry-Pérot interferometry [4] and signatures of whispering gallery modes. This work unlocks new possibilities in the field of electron optics in graphene.

[1] M.A. Eriksson et al., Appl. Phys. Lett. 69, 671 (1996); M. Topinka et al., Science 289, 671 (2000).

[2] F. Martins et al., Phys. Rev. Lett. 99, 136807 (2007) ; M. Pala et al., Phys. Rev. B 77, 125310 (2008).

[3] B. Brun et al., Phys. Rev. B 100, 041401 (2019).

[4] B. Brun et al., arXiv:1911.12031.
(Invited) Plasmon Induced Near-infrared Fluorescence Enhancement of Single-walled Carbon Nanotubes
Authors: Amirjani Amirmostafa , Tsoulos Theodoros , Antonucci Alessandra , Wu Shang-Jung , Tagliabue Giulia , Fatmehsari Davoud , Boghossian Ardemis Anoush
Published: May 2020

The near-infrared emissions of single-walled carbon nanotubes (SWCNTs) falls within the optical transparency window of biological tissue, allowing deep-tissue, in vivo and in vitro imaging. However, the relatively low photoluminescence quantum yield of SWCNTs, which typically lies in the range of 0.1 - 1.5%, limits the penetration depth and sensitivity of these fluorophores when used as imaging agents and optical sensors. In the present work, we enhance the fluorescence emission of SWCNTs up to 10-fold by employing different localized surface plasmon resonance (LSPR) nanostructures. We observe a chirality-dependent enhancement that varies with the nanostructure geometry and material. The proposed mechanism is based on changes in the charge density following nanoparticle conjugation with the SWCNT. In agreement with this mechanism, the enhancement and quenching effects show a strong correlation with the distance between the SWCNTs and the nanostructures. Finally, we demonstrate the applicability of this technology in a single-molecule imaging SWCNT application.
(Keynote) Exciton Manipulation in Heterostructures of 2D Materials
Authors: Kis Andras
Published: May 2020

The discovery of graphene marked the start of research in 2D electronic materials which was expanded in new directions with MoS2 and other layered semiconducting materials. They have a wide range of interesting fundamental properties and potential applications. New opportunities are enabled by the band structure of transition metal dichalcogenides (TMDCs) in which we could harness the valley degree of freedom for valleytronics and next-generation photonics. Long-lived interlayer excitons in van der Waals heterostructures based on TMDCs have recently emerged as a promising platform for this, allowing control over exciton diffusion length, energy and polarisation. I will show here how by using MoS2/WSe2 van der Waals heterostructures, we can realize excitonic transistors with switching action, confinement and control over diffusion length at room temperature in a reconfigurable potential landscape. Heterostructures with a long-range moiré potential such as in MoSe2/WSe2, on the other hand, offer the way to control polarization, emission and wavelength emitted by different optically active regions in the moiré.

References

[1] A. Ciarrocchi, D. Unuchek, A. Avsar, K. Watanabe, T. Taniguchi, A. Kis. Nature Photonics 13, 131–136 (2019).

[2] D. Unuchek, A. Ciarrocchi, A. Avsar, K. Watanabe, T. Taniguchi, A. Kis. Room-Temperature Electrical Control of Exciton Flux in a van Der Waals Heterostructure. Nature 560, 340–344 (2018).

[3] D. Unuchek, A. Ciarrocchi, A. Avsar, Z. Sun, K. Watanabe, T. Taniguchi, A. Kis. Valley-Polarized Exciton Currents in a van Der Waals Heterostructure. Nature Nanotechnology (2019); DOI:10.1038/s41565-019-0559-y.
(Invited) Optical Properties and Active Plasmon Excitations in 2D Materials
Authors: Henrard Luc
Published: May 2020

The control and tuning of the optical properties of materials and the localization of electromagnetic energy are long standing quests for scientists. Not only it allows to design new classes of adaptive devices such as smart windows but also to perform surface enhanced vibrational spectroscopies such a SERS.

For metallic nanostructured systems, the optical properties are directly related to collective electronic excitation (plasmons) and they depend mainly on the composition, shape and size of the system. Doped semiconductors such as Indium Tin Oxide have been also shown to display active plasmon, i.e., optical excitations that can be easily controlled by an external stimulus, e.g. a static electric potential [1].

In 2D materials, an electrostatic doping is common due to the low density of state at the Fermi energy. Moreover, anisotropy plays a very specific role [2] and surface plasmon became 1D plasmon. In this presentation, based on numerical simulations, we analyze the plasmon excitation associated to edge of 2D materials or to metallic mirror twin boundaries in Transition Metal Dichalcogenide [3]. Doped graphene [4] nanodots or shape engineering in wrinkled structures will also be discussed.

[1] A. Maho et al. Solar Energy Materials and Solar Cells 200 (2019) 110014

[2] B. Majerus et al. Phys. Rev. B 98 (2018) 125419

[3] A. A. Koos et al. J. Phys. Chem 123 (2019) 24855

[4] F. Joucken et al. Phys. Rev. Mat. 3 (2019) 110301
(Invited) Towards Industrialization of Boron Nitride Nanotubes: Purification and Quality Assessment
Authors: Simard Benoit
Published: May 2020

Boron nitride nanotubes (BNNTs) exhibit a range of properties that are as impressive as their isoelectronic carbon nanotube (CNT) cousins but with unique features including substantially higher thermal stability, wide band gap, transparency in the visible region and better biocompatibility1. Historically, very low production volume has prevented the science and technology of BNNTs from evolving at even a fraction of the pace of CNTs. We have addressed this limitation through the development of an industrially scalable plasma process for the manufacturing of BNNT2,3. Although kg quantities of BNNT can now be synthesized daily, the material contains several impurities which must be removed to exploit fully the superlative properties of BNNT in various applications. In the first part of the talk, I will present our recent advances in purification. We have developed a gas phase process that raises the purity of as-produced BNNT above 90% in a single-step. The process relies on the use of pure or diluted chorine gas at high temperature. The process has been examined at various temperatures, up to 1050 °C, using a range of imaging and spectroscopic assessments. The next step in advancing the field of BNNT is the development of a method for quality (purity + defect density) assessment of bulk samples, an area that has plagued the field of carbon nanotubes for more than 30 years. In the next part of the talk, I will show how the specific and strong interfacial interaction between regio random poly(3-hexyl thiophene) (rra-P3HT) and BNNT leads to the emergence of structured absorption and emission bands that can be used to quantify the relative quality of BNNT samples4,5.

1. J. Augustine, T. Cheung, V. Gies, J. Boughton, M. Chen, Z. J. Jakubek, S. Walker, Y. Martinez-Rubi, B. Simard and S. Zou, Nanoscale Advances, 1, 1914-1923 (2019).

2. K. S. Kim, C. T. Kingston, A. Hrdina, M. B. Jakubinek, J. Guan, M. Plunkett and B. Simard, ACS Nano, 2014, 8, 6211-6220.

3. K. S. Kim, M. Couillard, H. Shin, M. Plunkett, D. Ruth, C. T. Kingston and B. Simard, ACS Nano,12, 884-893 (2018).

4. Y. Martinez-Rubi, Z. J. Jakubek, M. B. Jakubinek, K. S. Kim, F. Cheng, M. Couillard, C. Kingston and B. Simard, J. Phys. Chem., C, 119, 26605 (2015).

5. Y. Martinez Rubi, Z. Jakubek, M. Chen, S. Zou, and B. Simard, ACS Applied Nano, 2, 2054-2063 (2019).
(Invited) How to Use Acoustic Phonons to Enrich the Properties of a Cavity Coupled Nano-Emitter?
Authors: Borel Antoine , Claude Theo , Jeantet Adrien , Lauret Jean-Sébastien , Doorn Stephen K. , Voisin Christophe , Chassagneux Yannick
Published: May 2020

Carbon nanotubes have emerged as original single photon source in the near IR and in the telecom bands. To further control their emission rate and directionality, individual carbon nanotube can be coupled to a high Q and small mode volume cavity (Purcell effect). Due to the 1D geometry of carbon nanotube, the coupling between localized exciton and acoustic phonon is particularly strong. This coupling can be used as an additional degree of freedom in cavity coupled single emitters; it brings a very rich physics involving non-markovian decoherence, tripartite coupling, and asymmetric energy exchange... In particular the coupling to phonon can be used to “force” the nanotube to emit preferentially at the cavity frequency rather than at its intrinsic transition frequency. We implemented this approach to realize a widely tunable single photon source.

Jeantet et al, PRL 116, 247402 (2016)

Jeantet et al, Nano Lett. 17, 4184 (2017)

He et al, Nat. mat. 17, 663 (2018)

Chassagneux et al, PRB 97, 205124 (2018)
(Invited) Shedding Light on the Chiral Selectivity of Carbon Nanotube Growth
Authors: Tran Huy-Nam , Pimonov Vladimir , Monniello Léonard , Vialla Rémy , Prévot Guillaume , Tahir Saïd , Michel Thierry , Jourdain Vincent
Published: May 2020

Growing single-walled carbon nanotubes (SWCNTs) with high selectivity for specific chiralities is a matter of intense research activity with important implications in the fields of electronic and optoelectronic devices. However, a fundamental understanding of the dependence of each growth step (nucleation, elongation, chirality change, termination) on the nanotube chirality is still missing to allow a rational design of highly selective growth methods. In this presentation, we will show how a newly developed method of optical imaging [1,2] allows the in situ observation of individual SWCNTs in real conditions of growth (i.e. at atmospheric pressure on a substrate) and with time resolution down to a few tens of ms. Based on these observations, we will report on the dependence of the growth kinetics (rate, lifetime) of individual SWCNTs on the growth conditions (temperature, carbon supply) and on the SWCNT chirality (diameter, chiral angle). We will also report a comprehensive method to model the optical spectra of individual SWCNTs on substrate obtained with the same polarization-based setup [2]. Importantly, this model includes the influence of the commonly used anti-reflection substrates (e.g. SiO2/Si), and of coherent and non-coherent depolarization by the optics. This model allows extracting both the real and imaginary parts of the nanotube susceptibility and improving the chirality assignment when coupled with complementary techniques such as Raman spectroscopy.

[1] Liu et al, Nature Nanotechnology (2013), 8, 917.

[2] Comprehensive model of the optical spectra of carbon nanotubes on a substrate by polarized microscopy, L. Monniello, H.-N. Tran, R. Vialla, G. Prévot, S. Tahir, T. Michel, V. Jourdain, Physical Review B (2019), 99, 115431.

Figure 1
Recovery and Isolation of Higher Fullerenes and Metallofullerenes Via Selective Chemical Release from Waste Materials
Authors: Tepper Katelyn R. , Stevenson Steven
Published: May 2020

Moving beyond the conventional HPLC approach to isolating fullerenes and endohedrals, scientists have begun using chemical methods to selectively bind either contaminant or desired species. Recently, we introduced aminopropanol as a reagent that would selectively react with spheroidal fullerenes to form water soluble derivatives, with unreacted tubular fullerenes (Fullertubes) remaining in the organic phase. In this presentation, we address the fate of the functionalized spheroidal fullerenes. These spent reaction mixtures are typically discarded as waste material. The aim of my project is to chemically release and recover pristine fullerenes and metallofullerenes. In this presentation, I will discuss our recent progress into the recovery and isolation of new higher fullerene and endohedral species. This selective release approach permits the isolation of new carbon structures.
Pyridine-Functionalized Fullerene Electron Transport Layer for Efficient and Flexible Perovskite Solar Cells
Authors: Deng Lin-Long , Xie Su-Yuan
Published: May 2020

Designing low-temperature solution-processed electron transport layer (ETL) for perovskite solar cells (PSCs) is important to realize low-cost and large-scale manufacturing of PSCs. Herein, we successfully synthesized a novel pyridine-functionalized fullerene derivative [6,6]-(4-pyridinyl)-C61-ethyl acid ethyl ester (PyCEE), which can act as an excellent ETL for n-i-p type PSCs. Due to its suitable energy levels, high electron mobility, and coordination interactions with the Pb2+ within perovskite, PyCEE-based PSCs displayed a power conversion efficiency (PCE) of 18.27% with dramatically suppressed hysteresis, superior to that of the TiO2-based control devices. Benefitting from the low-temperature and solution processability of PyCEE, it was further applied in flexible PSCs and a PCE of 15.25% was obtained, which demonstrates its applicability in flexible PSCs and provides new opportunity for large-scale production and commercialization of PSCs.
Encapsulated Yttrium Atoms in Carbon Cages: Spheres or Tubes?
Authors: Franklin Hannah M. , Stevenson Steven
Published: May 2020

Yttrium clusters entrapped within smaller C60-C90 fullerene cages are well known. However, there is minimal literature for yttrium atoms entrapped in the larger carbon cages. To avoid the separation nightmare that is soot extract, we simplify the mixture by chemically removing co-eluting contaminants. Herein, we describe a selective chemical reaction that effectively serves as a pre-cleanup step prior to introducing HPLC fraction collection. In Stage 2, the enriched Y-based carbon species are readily isolated chromatographically. In this presentation, we describe our two-step purification of yttrium atoms entrapped in the larger carbon cages, (e.g., C92-C102). Subsequent characterization, such as UV-Vis, of these yttrium metallofullerenes are underway.
Application of Carbon Quantum Dots in the Field of Nanosensors
Authors: Jiang Li
Published: May 2020

Compared with traditional semiconductor quantum dots, carbon quantum dots show adjustable excitation wavelength and emission wavelength, good stability, weather resistance and light resistance. Moreover, their photoluminescence properties, good biocompatibility and easy surface modification provide a wide application in life sciences and tracer sensing. Therefore, the study of carbon quantum dots will definitely promote the development of materials science, and it will also gain more attention for the carbon material family. Firstly, an “on–off–on” fluorescent phosphorus/nitrogen co-doped carbon dot (PNCD) probe was explored for the determination of Cr(VI) and dopamine resulting from the inner filter effect (IFE). The blue-emitting carbon dots with high quantum yields of 25.47% as well as a narrow size distribution were synthesized by a rapid, convenient route using H3PO4 and ethylenediamine as the precursors without any surface passivation. A wide linear region in the range of 7–70 mM with a detection limit of 0.71 mM was achieved for Cr(VI). Moreover, the proper reductants can weaken the inner filter effect to recover the PNCD fluorescence by converting Cr(VI) into Cr(III). Therefore, the PNCDs/Cr(VI) hybrid could also be used as an “off–on” fluorescent probe for detecting dopamine (DA) with a detection limit of 0.49 mM. Consequently, the PNCDs could serve as a powerful fluorescent bi-sensor for detection of both Cr(VI) and DA in practical applications. Then, a kind of water-soluble P, N, B-co-doped carbon quantum dots (PNBCDs) synthesized using a convenient hydrothermal method exhibit many excellent features, such as strong fluorescence, excitation independent emission, high mono-dispersity, good stability, and excellent water solubility with a fluorescence quantum yield of 21.95%. The as-prepared PNBCDs possessed remarkable selectivity and sensitivity towards curcumin with the linear range of 0–1.5 mmol L-1 and the detection limit for curcumin was 68 nmol L-1 (3s/k). Additionally, the wonderfully reversible and repeatable sensitivity to external temperature makes it possible that the PNBCDs could be used as a biocompatible fluorescent ink and for thermo-sensitive devices.
(Invited) Large π-Extended Carbon Crowns and Cylinders As Conjugated Segments of Single-Walled Carbon Nanotubes
Authors: Du Pingwu , Huang Qiang , Wang Jinyi , Wang Shengda , Huang Pingsen
Published: May 2020

Carbon exists as a variety of nanometer-sized allotropes, such as 0D fullerenes, 1D carbon nanotubes (CNTs), and 2D graphene. So far, it is still a great challenge to construct CNTs with a fixed length and diameter-specified single-chirality.1-2 In this talk, we will discuss synthesis and properties of a series of novel large π-extended molecular carbon crowns and cylinders as a finite model of single-walled CNTs, including TCR, HCR, and their C60 complexes et al.3 The nanographene HBC unit can be facilely embedded into cycloparaphenylene rings by Pd-mediated coupling reactions and the structure can be confirmed by crystal structure.2 Their macrocyclic structures of these nanocarbons have also been characterized using various physical methods, including NMR, STM, PL, crystallographic analysis. The photophysical properties of these molecules are studied in solution and explained by theoretical calculations. In addition, the ring-shaped structure can be inserted into a poly(para-phenylene) backbone as a polymeric segment (PS1) of single-walled CNTs.4 PS1 is achieved by a rationally designed synthesis of a bifunctionalized cyclo-para-phenylene monomer, followed by inserting these ring-shaped units into the conjugated poly(para-phenylene) chain. All these π-extended nanocarbons can provide new insight for the development of bottom-up syntheses of uniform carbon nanotube segments and potential applications in electron- and hole-transport devices.

References

1. Lu, D. P.; Wu, H. T.; Dai, Y. F.; Shi, H.; Shao, X.; Yang, S. F.; Yang, J. L.; Du, P. W. * Commun.
2016, 52, 7164-7167.

2. Lu, D.P.; Zhuang, G. L.; Wu, H. T.; Wang, S.; Yang, S. F.; Du, P. W.* Chem., Int. Ed.
2017, 56, 158-162

3. Cui, S. S.; Zhuang, G. L.; Lu, D. P.; Jia, H. X.; Wang, Y.; Yang, S. F.; Du, P. W. * Chem., Int. Ed.
2018, 57, 9330-9335.

4. Qiang Huang,Q.; Zhuang, G. L.; Jia,H.X.; Qian, M. M.;Cui, S. S.; Yang, S. F.; Du, P. W.*. Chem., Int. Ed., 2019, 58, 6244-6249.

5. Qiang Huang,Q.; Zhuang, G. L.; Zhang, M. M.; Wang, J. Y.; Wang, S. D.; Wu, Y. Y.; Yang, S. F.; Du, P. W.*. Am. Chem. Soc., 2019, DOI: 10.1021/jacs.9b10358.

Figure 1
(Invited) Dimerization of C30H10 Employing the Diels-Alder Cycloaddition Reaction
Authors: Richaud Arlette , Lopez Maria J. , Mojica Martha , Alonso Julio A. , Méndez Francisco
Published: May 2020

The chemical synthesis of fullerenes is still a challenge.[1-4] The development of new techniques is needed to reduce the production cost and the availability of those materials.[5-10] In this work we study, using the density functional theory (DFT) and the nudge elastic band (NEB) method, a route to obtain the C60 from two pentacyclopentacorannulene C30H10 fragments. The accessible precursor of C60, is a C60H20 molecule, which is a C60 fullerene wrapped by a double belt of twenty H atoms forming C-H bonds around the equatorial plane of C60 (the poles are occupied by the central pentagons of the two fragments). The proposed C60H20 molecule has a synthetic analogue reported by Boltalina et al.[11] Our theoretical justification for the dimerization of the C30H10 fragments supports the achievable synthetic route for the C60.

References.

1.- Diederich, Y. Rubin, Angew. Chem. Int. Ed., 1992, 31, 1101.

2.- T. Scott, Angew. Chem. Int. Ed., 2004, 43, 4994.

3.- M. Tsefrikas, L. T. Scott, Chem.
Rev., 2006, 106, 4868.

4.- Mojica, F., J. A. Alonso, J. Phys. Org. Chem., 2013, 26, 526.

5.- T. Scott, M. M. Boorum, B. J. McMahon, S. Hagen, J. Mack, J. Blank, H. Wegner, A. de Meijere, Science, 2002, 295, 1500.

6.- Otero, G. Biddau, C. Sánchez-Sánchez, R. Caillard, M. F. López, C. Rogero, F. J. Palomares, N. Cabello, M. A. Basanta, J. Ortega, J. Méndez, A. M. Echavarren, R. Pérez, B. Gómez-Lor, J. A. Martín-Gago, Nature, 2008, 454, 865.

7.- B. M. Ansems, L. T. Scott, J. Am.
Chem. Soc., 2000, 122, 2719.

8.- H. F. Bunz, Y. Rubin, Y. Tobe, Chem. Soc. Rev., 1999, 28,107.

9.- L. Chapman, M. R. Engel, J. P. Springer, J. C. Clardy, J. Am. Chem. Soc., 1971, 93, 6696

10.- T. Scott, M. A. Petrukhina, Preface in Fragments of Fullerenes and Carbon Nanotubes: Designed Synthesis, Unusual Reactions and Coordination Chemistry; L. T. Scott, M. A. Petrukhina, Eds.; John Wiley & Sons Inc., Hoboken, New Jersey, 2012, pp. vii–x.

11.- V. Boltalina, V. Yu. Markov, P. A. Troshin, A. D. Darwish, J. M. Street, and R. Taylor, Angew. Chem. Int. Ed., 2001, 40, 787.
(Invited) Synthesis and Structural Characterization of Actinide Cluster Fullerenes
Authors: Chen Ning , Zhuang Jiaxin , Li Xiaomeng
Published: May 2020

The hollow internal cavity of fullerene buckyballs has been known to be able to encapsulate novel metallic units, especially those otherwise very reactive or virtually impossible to prepare clusters. In this talk, we will present our recent studies of novel cluster endohedral fullerenes, focusing on their unique encapsulated clusters and bonding motifs. The synthesis and characterization of U2C@C80 gives an unprecedented look into a long sought after but heretofore unknown U=C bond which lacks heteroatom support, allowing for detailed structural and electronic insights.Novel actinide cluster fullerenes, U2C2@Ih
(7)-C80 and U2C2@D
3h
(5)-C78, were synthesized and fully characterized by mass spectrometry, single crystal X-ray crystallography, UV-vis-NIR , Raman spectroscopy, IR spectroscopy, as well as density functional and multireference wavefunction calculations. The encapsulated U2C2 is the first example of a uranium carbide cluster featuring two U centers bridged by a C≡C unit. The U-C bond distances in these U2C2 clusters are in the range between 2.130-2.421 Å. While the U2C2 cluster in U2C2@C80 adopts a butterfly-shaped geometry with a U-C2-U dihedral angle of 112.7°and a U-U distance of 3.855 Å, the U-U distance in U2C2@C78 is 4.164 Å and the resulting U-C2-U dihedral angle is increased to 149.1°. The combined experimental and quantum-chemical results suggest that the formal U oxidation state is +IV in the U2C2 cluster.