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Improved Laser‐Based Photoluminescence on Single‐Walled Carbon Nanotubes
摘要： Photoluminescence (PL) is a common tool to characterize various properties of single-walled carbon nanotube (SWCNT) chirality distribution and the level of tube individualization in SWCNT samples. Most PL studies use conventional lamp light sources whose spectral distribution is filtered with a monochromator, but this results in a still impure spectrum with a low spectral intensity. Tunable dye lasers offer a tunable light source which cover the desired excitation wavelength range with a high spectral intensity, but their operation is often cumbersome. Herein, the design and properties of an improved dye-laser system which is based on a Q-switch pump laser are presented. The high peak power of the pump provides an essentially threshold-free lasing of the dye laser, which substantially improves the operability. It allows operation with laser dyes, such as Rhodamin 110 and Pyridin 1, which are otherwise on the border of operation of the laser. The system allows to cover the 540–730 nm wavelength range with four dyes. In addition, the dye laser output pulses closely follow the properties of the pump, which directly provides a time-resolved and tunable laser source. The performance of the system by measuring the PL map of a HiPco SWCNTs sample is demonstrated.
关键词： photoluminescence,carbon nanotubes,spectrometers,pulsed dye lasers
更新于2025-09-11 14:15:04
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Regrowth and catalytic etching of individual single-walled carbon nanotubes studied by isotope labeling and growth interruption
摘要： To realize the efficient growth of single-walled carbon nanotubes (SWCNTs), the growth mechanism behind catalyst activity and growth rates needs to be elucidated at the single nanotube level. In this study, we synthesized SWCNTs with growth interruption, where only Ar, Ar/H2, or Ar/H2/H2O was introduced during a pause in the supply of a carbon source, in order to examine the effects of additive molecules in a chemical vapor deposition process. This interrupted growth was performed in combination with an isotope labeling technique to show the time evolution of individual SWCNT growth. While the introduction of Ar during the growth interruption tended to terminate SWCNT growth, the introduction of Ar/H2 resulted in the regrowth of SWCNTs once ethanol was reintroduced. When interrupted with Ar/H2/H2O, SWCNTs were etched catalytically while sliding themselves in the reverse direction of growth and, then, regrew. Raman analysis revealed that the chirality of SWCNTs was preserved even after etching and regrowth. The growth rates of SWCNTs were unchanged before and after the interruption in the case of Ar/H2, but they were increased by a factor of ~1.7 in the case of Ar/H2/H2O. These results provide effective means to maintain the catalyst activity and to enhance growth rates.
关键词： Isotope labeling,Catalytic etching,Single-walled carbon nanotubes,Growth interruption,Chemical vapor deposition
更新于2025-09-11 14:15:04
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Ceramic Matrix Composites (Materials, Manufacturing and Engineering) || 5. Carbonaceous nanomaterials for hybrid organic photovoltaic application
摘要： The deployment of renewable energy sources is crucial for moving towards a sustainable society. In this context, photovoltaic (PV) solar energy conversion is a clean and practical technology with huge potential. However, it is not yet widely deployed; PV efficiency optimization and cost reductions could significantly expedite the uptake of novel solar technologies. To meet future PV power requirements it will be necessary to move toward innovative device design and ultimately new material systems. To this end, new approaches for solar energy conversion are being explored, including organic solar cells (OSCs) that offer the opportunity to diversify PV technologies. Organic and hybrid solar cells are poised to play a significant role in realizing long-term scenarios for sustainable and efficient sources of energy. Although the power conversion efficiency of OSCs is still considerably below that attainable by their inorganic semiconductor-based counterparts, other desirable characteristics, such as flexibility and low weight, make them ideal for specific niche applications, such as their integration into buildings (i.e. on roofs and semitransparent windows) and may ultimately allow the development of viable OPV sources for space applications.
关键词： photovoltaic,carbon nanotubes,organic solar cells,renewable energy,graphene
更新于2025-09-11 14:15:04
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Design of Refolding DNA Aptamer on Single-Walled Carbon Nanotubes for Enhanced Optical Detection of Target Proteins
摘要： DNA aptamer conjugated single-walled carbon nanotube (Aptamer-SWNT) hybrids have demonstrated effective optical biosensors because of its high selectivity and specificity to a target protein, however, the understanding of SWNT hybridization with an aptamer forming a secondary or tertiary structure is still lacking. We study wrapping methods dependent optical biosensing modulation by insulin and platelet-derived growth factor (PDGF) using the Aptamer-SWNT hybrids and the Aptamer-Anchor-SWNT hybrids with a periodically sequenced single-stranded DNA (ssDNA) as anchoring phases. We observe that the refolding nature of the aptamer and its combination with an anchoring phase are critical to the hybridization, where the remarkable optical sensing properties are attributed to the wrapping procedures including the direct wrapping with sonication and the indirect wrapping through dialysis. The tetrameric parallel-stranded G-quadruplex conformation of insulin binding aptamers (IBA) shows an enhanced fluorescence response quenching when using the directly wrapped Aptamer-Anchor-SWNT hybrids. In addition, helix-structural refolding of PDGF binding aptamers (PBA) on the SWNT vicinity under the indirect wrapping exhibits anchoring length-dependent optical modulation. Furthermore, the consecutive centrifuging processes with the indirect wrapping demonstrate fluorescence response brightening, in which the diameter dependent brightening effect is observed by aptamer-protein interactions. This study provides an understanding the underlying conjugation nature of both the Aptamer-SWNT and the Aptamer-Anchor-SWNT hybrids formation, facilitating exceptional optical sensing modules with consideration of refolding feature of aptamers, selection of anchoring phases, wrapping methods and centrifuging process, and the hybridization voyage for DNA-SWNT platforms maneuvers their outcoming optical biosensing capabilities.
关键词： insulin,single-walled carbon nanotubes,PDGF,wrapping methods,optical biosensing,DNA aptamer
更新于2025-09-11 14:15:04
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Laser-Induced Deposition of Carbon Nanotubes in Fiber Optic Tips of MMI Devices
摘要： The integration of carbon nanotubes (CNTs) into optical fibers allows the application of their unique properties in robust and versatile devices. Here, we present a laser-induced technique to obtain the deposition of CNTs onto the fiber optics tips of multimode interference (MMI) devices. An MMI device is constructed by splicing a section of no-core fiber (NCF) to a single-mode fiber (SMF). The tip of the MMI device is immersed into a liquid solution of CNTs and laser light is launched into the MMI device. CNTs solutions using water and methanol as solvents were tested. In addition, the use of a polymer dispersant polyvinylpyrrolidone (PVP) in the CNTs solutions was also studied. We found that the laser-induced deposition of CNTs performed in water-based solutions generates non-uniform deposits. On the other hand, the laser-induced deposition performed with methanol solutions generates uniform deposits over the fiber tip when no PVP is used and deposition at the center of the fiber when PVP is present in the CNTs solution. The results show the crucial role of the solvent on the spatial features of the laser-induced deposition process. Finally, we register and study the reflection spectra of the as-fabricated CNTs deposited MMI devices.
关键词： multimode interference,carbon nanotubes,laser-induced deposition,optical fibers
更新于2025-09-11 14:15:04
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Multiwalled carbon nanotube based aromatic volatile organic compound sensor: sensitivity enhancement through 1-hexadecanethiol functionalisation
摘要： Aromatic volatile organic compound (VOC) sensors are attracting growing interest as a response to the pressing market need for sensitive, fast response, low power consumption and stable sensors. Benzene and toluene detection is subject to several potential applications such as air monitoring in chemical industries or even biosensing of human breath. In this work, we report the fabrication of a room temperature toluene and benzene sensor based on multiwall carbon nanotubes (MWCNTs) decorated with gold nanoparticles and functionalised with a long-chain thiol self-assembled monolayer, 1-hexadecanethiol (HDT). High-resolution transmission electron microscopy (HRTEM) and Fourier transform infrared spectroscopy (FTIR) were performed to characterize the gold nanoparticle decoration and to examine the thiol monolayer bonding to the MWCNTs. The detection of aromatic vapours using Au-MWCNT and HDT/Au-MWCNT sensors down to the ppm range shows that the presence of the self-assembled layer increases the sensitivity (up to 17 times), selectivity and improves the response dynamics of the sensors.
关键词： multiwall carbon nanotubes (MWCNTs),vapour sensor,sensitivity,gold-decorated MWCNTs,self-assembled monolayers (SAMs),selectivity
更新于2025-09-11 14:15:04
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Self-assembly of single-walled carbon nanotubes arrays with different line width
摘要： Single-walled carbon nanotubes (SWNTs) are one of the most promising nanoelectronic materials, However, there are still some application challenges, including purification, regular arrangement, interconnection, and so on. There is evidence that the array assembly can improve the performance of SWNTs. In this work, we develop a line-width controllable large-scale assembly of SWNTs based on aqueous solution, using electron beam (E-beam) lithography to construct self-assembled templates. The results show that SWNTs arrays of different line-width are obtained, which is possible to design the structure of SWNTs assembly to meet different functions.
关键词： Single-walled carbon nanotubes (SWNTs),self-assembly,line-width,electron beam (E-beam) lithography
更新于2025-09-11 14:15:04
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Enhanced Charge Carrier Transport in 2D Perovskites by Incorporating Single-Walled Carbon Nanotubes or Graphene
摘要： Two-dimensional (2D) organic-inorganic (hybrid) perovskites are considered promising candidates to replace conventional three-dimensional (3D) perovskites for solar cell applications as they have good resistance against moisture and UV light. However, the use of 2D perovskite is associated with a significant decrease in power efficiency resulting from their low photogenerated charge carrier density and poor charge transport. To improve power efficiency in 2D perovskites, highly crystalline films (near-single-crystal quality) of 2D perovskite needs to be synthesized where the alignment of the inorganic perovskite components is controlled to have vertical alignment with respect to the contacts to improve charge transport. In this work, we explored strategies to overcome this limitation, by integrating 2D perovskite with single-walled carbon nanotubes or graphene to enable more efficient extraction of charge carriers toward electric contacts. Longer carrier lifetimes were achieved after the incorporation of the carbon nanostructures in the films and at cell level, power efficiency increased by two-fold.
关键词： 2D perovskites,charge-carrier transport,solar cells,single-walled carbon nanotubes,graphene
更新于2025-09-11 14:15:04
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Single‐Photon Emission: Brightening and Guiding Single‐Photon Emission by Plasmonic Waveguide–Slit Structures on a Metallic Substrate (Laser Photonics Rev. 13(10)/2019)
摘要： In this work, we report a new mixed-extractor strategy to improve the sorting yield of large-diameter semiconducting single-walled carbon nanotubes (s-SWCNTs) with high purity. In the new mixed-extractor strategy, two kinds of conjugated polymers with different rigidity, poly(9,9-n-dihexyl-2,7-fluorene-alt-9-phenyl-3,6-carbazole) (PDFP) and poly(9,9-dioctylfluorene-alt-benzothiadiazole) (P8BT), are used to sort large-diameter s-SWCNTs through two simple sonication processes. To our surprise, although PDFP itself shows no selectivity toward s-SWCNTs, it can greatly enhance the sorting yield of P8BT. Using the PDFP/P8BT mixed-extractor method, the yield of sorted s-SWCNTs has been enhanced by 5 times with a purity above 99 % in comparison to that using P8BT single-extractor method. In addition, the photoluminescence (PL) excitation maps shows that the PDFP/P8BT mixed-extractor system not only enhances the sorting yield substantially, but also tends to be enrichment of (15,4) SWCNTs with the diameter of 1.36 nm.
关键词： mixed-extractor,high yield and high purity sorting,carbon nanotubes,polymer
更新于2025-09-11 14:15:04
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Exciton Peierls mechanism and universal many-body gaps in carbon nanotubes
摘要： “Metallic” carbon nanotubes exhibit quasiparticle gaps when isolated from a screening environment. The gap-opening mechanism is expected to be of electronic origin, but the precise nature is debated. In this work, we show that hybrid density functional theory predicts a set of excitonic instabilities capable of opening gaps of the size found in experiment. The excitonic instabilities are coupled to vibrational modes and, in particular, the modes associated with the (cid:2) ? E2g and K ? A(cid:2) 1 Kohn anomalies of graphene, inducing Peierls lattice distortions with a strong electron-phonon coupling. In the larger tubes, the longitudinal optical phonon mode becomes a purely electronic dimerization that is fully symmetry conserving in the zigzag and chiral tubes, but breaks the symmetry in the armchair tubes. The resulting gaps are universal (i.e., independent of chirality) and scale as 1/R with tube radius.
关键词： exciton Peierls mechanism,electron-phonon coupling,many-body gaps,carbon nanotubes,hybrid density functional theory
更新于2025-09-11 14:15:04