bluuebunny/crossref_metadata_2025_split huggingface dataset:
Carbon Nanotubes - the p-Type Contact of the Future for Perovskite Solar Cells?
Authors: Habisreutinger Severin N. , Noel Nakita K. , Snaith Henry J. , Nicholas Robin J. 
Published: February 2020

The enormous strides researchers have made in advancing perovskite based photovoltaics in the past few years are fueling the dream of a rapid entry of this highly promising technology into the global energy market. This seems like serendipitous timing since solar power has gained an enormous momentum over the past decade exceeding all projections. This expansion in solar power is driven by an increasing understanding that climate change requires immediate action, in particular with regards to power generation; and simultaneously, the price for photovoltaic modules has remarkably quickly fallen to make solar power generation competitive vis-à-vis conventional technologies.
Compositional tuning of the perovskite absorber has led to immense improvements in stability and efficiency of perovskite solar cells leading to a certified efficiency of 22.7% for a single-junction laboratory device. The successful transition of a photovoltaic technology from the lab into the field requires, however, two additional important parameters aside from efficiency which are essential for real-world deployment: stability and scalability.
We propose using single-walled carbon nanotubes (SWCNTs) as p-type layer for perovskite solar cells for future applications.
Carbon nanotubes combine several highly attractive characteristics such as chemical inertness and mechanical resilience with intrinsically high charge-carrier mobilities endowing them with a unique potential to be a very stable dopant-free charge-selective contact. Furthermore, the SWCNT deposition techniques for large-scale use, such as spray-coating, are already well-established, opening clear avenues for direct implementation in a real-world industrial setting.
In this study, we demonstrate that employing SWCNTs as hole-transporting material can yield steady-state efficiencies of above 20% for alloyed narrow bandgap perovskites, and of over 7% for wide-bandgap perovskites, illustrating the versatility and excellent performance of SWCNTs as charge-selective contact material.
(Invited) From Thermopower Waves to Asymmetric Chemical Doping – New Concepts in Energy Storage and Generation Using Molecular Interactions with Single-Walled Carbon Nanotubes
Authors: Liu Albert Tianxiang , Strano Michael S , Kunai Yuichiro , Liu Pingwei , Cottrill Anton 
Published: February 2020

There is a pressing need to find alternatives to conventional energy generation techniques, specifically those that rely on elements in finite global supply. Thermopower wave (TPW) devices, which convert chemical to electrical energy by means of self-propagating reaction waves guided along nanostructured thermal conduits, have the potential to address this demand.1 We show that conversion efficiency can be increased significantly by selecting molecules such as sodium azide or sucrose with potassium nitrate to offset the inherent penalty in chemical potential imposed by strongly p-doping chemicals,2 a validation of the predictions of Excess Thermopower theory.3 Such chemical-potential-gradient-induced-electricity can be further exploited in a more direct manner, decoupled completely from the combustion reactions, affording another novel energy generation scheme using only molecular interactions, and subsequent charge transfers, with single-walled carbon nanotubes.4 Specifically, we demonstrate that chemically-modified carbon nanotube fibers enable unique power sources driven entirely by a chemical potential gradient.5 Short circuit electrical current (11.9 μA mg−1) and open circuit potential (525 mV) are reversibly produced by localized acetonitrile doping under ambient conditions. An inverse length-scaling of the maximum power as L−1.03 that creates specific powers as large as 30.0 kW kg−1 highlights the potential for microscale energy generation.
(1) Choi, W.; Strano, M. S. et. al. Nat Mater
2010, 9.
(2) Mahajan, S. G.; Liu, A. T.; Strano, M. S. et. al. Energy & Environmental Science
2016, 9, 1290.
(3) Abrahamson, J. T.; Strano, M. S. et. al. ACS Nano
2013, 7, 6533.
(4) Kunai, Y.; Liu, A. T.; Strano, M. S. et. al. J. Am. Chem. Soc.
2017, 139, 15328.
(5) Liu, A. T.; Kunai, Y.; Strano, M. S. et. al. Adv. Mater.
2016, 28, 9752.
Xeno Nucleic Acids for Enhancing the Optical Stability of Nanosensors
Authors: Gillen Alice Judith , Gigli Carlo , Boghossian Ardemis Anoush 
Published: February 2020

The unique optoelectronic properties of single-walled carbon nanotubes (SWCNTs) motivate their use as next-generation optical sensors. The intrinsic SWCNT near-infrared fluorescence offers many advantages in terms of bio-transparency, sensitivity, and photo-stability. Characteristics required for in vivo continuous sensing, such as selectivity, biocompatibility, and solubility, can be tuned by suspending SWCNTs with biomolecules such as single-stranded DNA (ssDNA). Despite the ubiquitous use of DNA-wrapped SWCNTs for a variety of in vivo sensing applications, their behaviour in the presence of varying concentrations of the different ions present in biological media has yet to be studied.
In this work, we present a systematic exploration of the effects of various cations and anions on the fluorescence of ssDNA-wrapped SWCNTs. The presence of multivalent cations was found to induce fluorescence shifting of near-infrared fluorescence through the transient formation of a metastable state. The incorporation of artificial oligonucleotides, or xeno nucleic acids, was shown to mitigate the effects of ion-induced conformal drift through improved conformational resiliency. The synthetic biology approach presented herein offers a powerful demonstration for enhancing sensor selectivity and stability while enabling a previously unexplored space for engineering oligonucleotide-based SWCNT sensors.
Nanocarbon-Based Field-Effect Transistor Biosensors (bioFETs) for Real-Time Detection of DNA Sequences
Authors: Bazan Claudia Marcela , Sauvage Madline , Huliganga Elizabeth , Bencherif Amira , Borduas Godefroy , Bouilly Delphine 
Published: February 2020

Field-effect transistor devices based on functionalized nanocarbon materials (2-D graphene thin layers and 1-D carbon nanotubes) are a promising technology for biomolecular sensing applications. In particular, this type of devices allows for label-free detection of DNA hybridization with the advantage of an easy and direct electrical readout in comparison with most routine techniques.
In this work, we report on the design and fabrication of nanocarbon-based bioFETs for DNA hybridization detection. Employing a combination of microfluidics and real-time electrical measurements, we investigated the response of bioFETs to single-stranded DNA (ssDNA) probe tethering and hybridization with complementary target ssDNA in saline buffer solution. The bioFETs were assembled from individual carbon nanotubes or graphene nanoribbons connected by pairs of metallic electrodes using photolithography techniques. Transfer curves of bioFETs in saline buffer were measured using an immersed pseudo-reference electrode. We obtained transfer curves showing current modulation with high OFF-current at the charge-neutrality point. Probe and target ssDNA were chosen as 22-nucleotide-long complementary sequences. Probe tethering on nanocarbon was obtained using diazonium chemistry followed by EDC/NHS coupling of an amine moiety placed at the extremity of the DNA probe [1]. Transfer characteristics were measured before/after probe and target injection. Moreover, to further characterize the bioFETs response, probe immobilization and probe-target hybridization were recorded in real-time using electrical readout. The development of highly selective and ultra-sensitive sensors for DNA will open novel technological avenues to improve the detection of genetic biomarkers for various diseases.
[1] Bouilly, D. et al. Nano Letters 16, 4679–4685 (2016)
(Invited) Systematic Aqueous Two-Phase Separations of Carbon Nanotubes to Investigate the Separation Mechanism
Authors: Defillet Joeri , Martinati Miles , Wenseleers Wim , Cambre Sofie 
Published: February 2020

Aqueous two-phase (ATP) separation has been demonstrated as a fast, highly-scalable separation technique to sort single-wall carbon nanotubes (SWCNTs) by diameter, chirality, metallicity, etc.[1-2] In ATP, two water-soluble, yet immiscible polymers are mixed together at sufficiently high concentration after which they spontaneously form two phases with different hydrophilicity. In a typical separation protocol, SWCNTs are added to this two-polymer mixture with a combination of different surfactants, resulting in separation of different chiral species among both phases. While very promising separations have been achieved, the separation mechanism is not well understood
In this paper, we present a series of ATP separations, in which surfactant combinations and concentrations are systematically varied. Absorption spectroscopy, multi-wavelength resonant Raman scattering and wavelength-dependent photoluminescence-excitation spectroscopy, combined with detailed two-dimensional spectral analysis, is applied to characterize the full composition of the resulting separated fractions and as such study the underlying separation mechanism. These systematic studies reveal that chirality-dependent surfactant interactions determine the separation order.
[1]. C.Y. Khripin et al., J. Am.
Chem. Soc.
2013, 135, 6822
[2]. N.K. Subbaiyan et al., ACS Nano
2014, 8, 1619
(Keynote) Carbon Nanotubes: Discovery and Beyond
Authors: Iijima Sumio 
Published: February 2020

First I would like to present how the carbon nanotube (CNT) was discovered after my long research carrier in 1991, emphasizing on a scientific and convincing presentation of the finding [1]. It might be interesting to talk about what I have been doing before the discovery, where I should introduce my ample experiences with high resolution electron microscopy (HRTEM) and its use in structure characterizations of various nano-structured materials in atomic detail [2]. Without this tool and technique there will be no chance for finding the carbon nanotube. The carbon nanotubes brought us dual excitements in both academia as condensed matter physics and industrial applications. Such a broad range of the attraction is reflected in an extremely high Google citation, its number becoming over 45,000 only for the first paper reporting CNT in 1991. The number is still increasing even after 27 years of the discovery.
CNT, chrysotile asbestos, imogolite [3], and many structures in biological systems are known to have tubular structures, resulting from anisotropic growth in one particular orientation. In the case of CNT, the presence of catalytic metal particles in the tubule formation appears to control a tubular morphology. In general, the formation of nanometer-scale tubular structures is caused mostly by molecular conformation of a building block unit or a total energy minimization of the tubular structure system.
We have recently examined aluminum oxy-hydroxide gamma-AlOOH, boehmite, which has been known to form into a variety of morphologies from a fibril, low-dimensional sheet, platelets, to bulk crystal, depending on a synthesis process. One of them is a quasi-one-dimensional fibril structure, which grows in an aqueous solution as a sol form. We have studied detailed morphology of this fibril boehmite and found that the fibril grows selectively parallel to the c-axis and does not form in a tubular structure but a nanometer-sized ribbon [4]. Electronic energy band gaps of such a ribbon have been studied and showed interesting size-dependent band gaps [5]. The growth was not promoted by a particular catalytic substance so that such an anisotropic growth should be originated from the boehmite structure itself and surroundings.

Iijima, Nature, 345, 56-58 (1991).

Iijima, J. Appl. Phys., 42, 5891-5893 (1971).

Wada et al., Amer. Mineral., 54, 50 (1969).

Iijima et al., PNAS, 113, 11759-11764 (2016).

M. Toyoda & S. Saito,private communication 2017.
Quantum Optical Studies on Sp3 Defects in Carbon Nanotubes
Authors: He Xiaowei , Htoon Han , Doorn Stephen K. 
Published: February 2020

The intentional incorporation of impurities and defects can serve as a powerful tool for modification of the electronic and optical properties of host nanomaterials and enabling of new functionalities.1 Introduction of sp
3 defects by covalent functionalization to single-walled carbon nanotubes (SWCNTs) generates new emission states red-shifted from the optical bandgap (E11) of SWCNTs by 100 to 300 meV.2 With controllable emission wavelengths and high quantum yield, these defect states open up new opportunities for the applications of SWCNTs in photonics such as lasing, photon upconversion and single photon emission.3-4

Recently, it has been shown that such doping sites are capable of emitting single photons at room-T, with single photon purity as high as 99% and emit at wavelengths from 1.1 μm to 1.55 μm covering the telecom O- and C-bands4. While the high single photon purity is of great importance, another critical criterial for an ideal single photon generator is photon indistinguishability, which requires the emission linewidth to be narrowed down to the Fourier transform-limitation.5

In this work, we investigated the environmental influences on the linewidth of defect-state emission in SWCNTs at cryogenic temperature (4K). sp3
defects were generated on the surface of surfactant and poly[9,9-dioctylfluorenyl-2,7-diyl] (PFO) wrapped (6,5)SWCNTs by aryl diazonium functionalization. Photoluminescence (PL) spectra of defect states were investigated under different environmental conditions, including surfactant wrapping, surfactant-free, PFO-wrapping tubes on polymer substrates. The result showed that the linewidth of the PL peaks is in the order of a few hundred of micro-eV for surfactant-free and PFO wrapping tubes. Furthermore, dynamic measurements revealed that for clean tubes, the PL lifetimes (T1) are as high as a few nanoseconds, reaching to the radiative decay limitation. These results indicate that the observed linewidth is largely contributed by dephasing time (T2). Increasing T2 will be the critical issue for further narrowing the linewidth to the transform-limitation region.
[1] Piao, Yanmei. et al. Nature Chem. 2013, 5, 840.
[2] Hartmann, Nicolai F. et al. Nanoscale. 2015, 7,20521.
[3] Ma, Xuedan. et al. Nature Nanotech. 2015, 10, 671.
[4] Xiaowei He. et al. Nature Photonics. 2017, 11, 577.
[5] Yue Luo. et al. Nature communication. 2017, DOI: 10.1038/s41467-017-01777-w
(Invited) Aryl-Functionalized Single-Walled Carbon Nanotubes Embedded into Metallo-Dielectric Antennas
Authors: Shayan Kamran , He Xiaowei , Luo Yue , Li Xiangzhi , Blackburn Jeffrey L. , Doorn Stephen K. , Htoon Han , Strauf Stefan 
Published: February 2020

Creating exciton localization via covalent sp3 functionalization of single-walled carbon nanotubes (SWCNTs) is a promising route to enhance the optical quantum yield and can furthermore lead to single-photon emission at room temperatures [1]. Of recent interest are aryl-functionalized SWCNTs that are protected by polyfluorene, for which we have recently shown that a variety of chemically and energetically distinct defect state exist that have their origin in topological variation in the chemical binding configuration of the monovalent aryl groups [2]. Here we extend our study by embedding aryl-functionalized SWCNTs into metallo-dielectric antennas that provide broadband coupling with near-unity light collection efficiencies by trapping air gaps on chip that form cavity modes. Scalable implementation is realized by employing polymer layer dry-transfer techniques that avoid solvent incompatibility issues, as well as a planar design that avoids solid-immersion lenses, resulting in a narrow output cone of ±15° that enables a priori fiber-to-chip butt coupling. In these devices the exciton emission from the aryl-functionalized sides (E11*) remains spectrally sharp with linewidth values near the resolution limit of about 35 meV. Interestingly, we find that the pump-induced dephasing for E11* exciton (0D exciton) is significantly reduced by more than 300% as compared to the E11 exciton (1D exciton), thereby preserving exciton coherence even into the high pump power regime, as needed for practical devices in quantum photonics. We will discuss how these findings provide a foundation to build unified descriptions on emergence of novel optical behavior from the interplay of covalent dopants, dispersants, and excitons in SWCNTs.
[1] He, X. et al. Tunable room-temperature single-photon emission at telecom wavelengths from sp3 defects in carbon nanotubes. Nature Photonics
11, 577–582 (2017).
[2] He, X. et al. Low-Temperature Single Carbon Nanotube Spectroscopy of sp3 Quantum Defects, ACS Nano, Articles ASAP (2017); DOI:10.1021/acsnano.7b03022
Magneto-PL Spectroscopy in Aryl Functionalized CNTs
Authors: Kim Younghee , He Xiaowei , Doorn Stephen K. , Htoon Han 
Published: February 2020

Recent developments in single wall carbon nanotube (SWCNT) functionalization chemistry introducing sp
3 defect sites via covalent attachment of chemical functional groups have made SWCNTs a promising material system for a variety of technologies. These defect states boost photoluminescence (PL) quantum yields and open new possibilities for SWCNTs as unique photon sources in emerging applications. In 2015, solitary oxygen defect states incorporated onto SWCNTs were shown to serve as room temperature (RT) single photon emitters at ~1300 nm [1]. More recently, this RT single photon emission (SPE) was further extended to cover 1550 nm telecommunication wavelength band via aryl sp
3 defect sites in SWCNTs of larger diameters [2]. The SPE of aryl sp
3 are also characterized with ultrahigh single-photon purity and enhanced emission stability approaching the shot-noise limit. While these properties make sp3
defects of SWCNTs very promising material of quantum information technology, establishing the functionalized SWCNTs as transformative materials for quantum technologies demands a detailed understanding and control of their fine electronic structure and quantum coherence properties. Aiming to meet this challenge here, we performed single defect magneto-PL optical spectroscopy on sp
3 defects of aryl functionalized SWCNT. Our work reveals indications that the defects possess complex excitonic fine structure that may open a route toward manipulating spin and/or angular momentum of the defect bound exciton for quantum information technology applications.
References
[1] X. Ma et al., Nat. Nanotech., 2015, 10, 671.
[2] X. He et al., Nat. Photon., 2017, 11, 577
(Invited) Avalanche Photoemission in Suspended Carbon Nanotubes: Light without Heat
Authors: Cronin Stephen B. , Wang Bo 
Published: February 2020

We report bright electroluminescence from suspended carbon nanotube (CNT) field effect transistors (FETs) under extremely low applied electrical powers (∼nW). Here, light emission occurs under positive applied gate voltages, with the FET in its “off” state. This enables us to apply high bias voltages (4 V) without heating the CNT. Under these
conditions, we observe light emission at currents as small as 1 nA and corresponding electrical powers of 4nW, which is 3 orders of magnitude lower than previous studies. Thermal emission is ruled out by monitoring the G band Raman frequency, which shows no evidence of heating under these small electrical currents. The mechanism of light emission is
understood on the basis of steep band bending that occurs in the conduction and valence band profiles at the contacts, which produces a peak electric field of 500 kV/cm, enabling the acceleration of carriers beyond the threshold of exciton emission. The exciton-generated electrons and holes are then accelerated in this field and emit excitons in an avalanche process. This is evidenced by an extremely sharp increase in the current with bias voltage (45 mV/dec). We also observe light emission at negative applied gate voltages when the FET is in its “on” state at comparable electrical powers to those reported previously (∼5 μW). However, substantial Joule heating (T > 1000 K) is also observed under these conditions, and it is difficult to separate the mechanisms of thermal emission from hot carrier photoemission in this regime.
Bo Wang, Fatemeh Rezaeifar, Jihan Chen, Sisi Yang, Rehan Kapadia and Stephen B. Cronin, ACS Photonics , DOI:10.1021/acsphotonics.7b00455 (2017)
(Invited) Diameter-Dependent Optical Absorption and Energy Transfer from Encapsulated Dye Molecules to Single Wall Carbon Nanotubes
Authors: Wenseleers Wim , Van Bezouw Stein , Campo Jochen , Cambré Sofie , Defillet Joeri , Arias Dylan , Ihly Rachelle , Ferguson Andrew John , Johnson Justin C. , Blackburn Jeffrey L. 
Published: February 2020

The hollow core and well-defined diameters of single-walled carbon nanotubes (SWCNTs) allow for creation of unique one-dimensional hybrid structures by encapsulation of various molecules. For instance, we previously demonstrated that in this way dipolar dye molecules can be naturally aligned in an ideal head-to-tail arrangement to create assemblies with a giant total nonlinear optical response.[1] Here, we show that the optical properties of dye molecules encapsulated in SWCNTs can be strongly modulated by the SWCNT diameter, indicating very specific diameter-dependent stacking and interactions of the molecules. The filling is thoroughly characterized by optical absorption, resonant Raman, and two-dimensional infrared photoluminescence excitation (PLE) spectroscopy. Energy transfer probed by PLE spectroscopy shows the absorption spectrum of the dyes to be strongly diameter-dependent, and transient absorption spectroscopy, simultaneously probing the encapsulated dyes and the host SWCNTs, demonstrates sub-picosecond EET from encapsulated molecules to the host SWCNTs. The design of these functional hybrid systems, with tuneable dye absorption, EET depending on the SWCNT diameter and the ability to remove all metallic SWCNTs by subsequent separation, demonstrates potential for implementation in dedicated photo-conversion devices.
[1] S. Cambré, J. Campo et al., Nature Nanotechnol. 10, 248 (2015).