Application Of Single-walled Carbon Nanotubes Research Articles

Dispersion of Single-Walled Carbon Nanotubes by Aromatic Cyclic Schiff Bases via Non-Covalent Interactions.

One of the challenging issues that hinders the application of single-walled carbon nanotubes (SWCNTs) is the poor solubility and the inevitable formation of bundles. Efforts still need to be made towards solving the problem. Herein, we report a non-covalent strategy to disperse aggregated SWCNTs by aromatic cyclic Schiff bases assisted by ultrasonic techniques. The aromatic cyclic Schiff base (OMM) was synthesized via Schiff base reactions, and the molecular structure was determined by ATR-FT-IR, solid-state 13C-NMR, and HRMS. Although the yielded product showed poor solubility in aqueous solution and organic solvents, it could interact with and disperse the aggregated SWCNTs in dimethyl formamide (DMF) under the condition of ultrasound. UV-vis-NIR, FL, Raman spectra, AFM, and TEM, along with computer simulations, provide evidence for the interactions between OMM molecules and SWCNTs and the dispersion thereof. The semiconductive (7,5), (8,6), (12,1), and (9,7)-SWCNTs expressed a preference for dissolution. The capability of dispersion is contributed by π-π, C-H·π, and lone pair (lp)·π interactions between OMM and SWCNTs based on the simulated results. The present non-covalent strategy could provide inspiration for preparing organic cyclic compounds as dispersants for SWCNTs and then facilitate their further utilization.

Recent advances on applications of single-walled carbon nanotubes as cutting-edge optical nanosensors for biosensing technologies.

Single-walled carbon nanotubes (SWCNTs) possess outstanding photophysical properties which has garnered interest towards utilizing these materials for biosensing and imaging applications. The near-infrared (NIR) fluorescence within the tissue transparent region along with their photostability and sizes in the nanoscale make SWCNTs valued candidates for the development of optical sensors. In this review, we discuss recent advances in the development and the applications of SWCNT-based nano-biosensors. An overview of SWCNT's structural and photophysical properties, sensor development, and sensing mechanisms are described. Examples of SWCNT-based optical nanosensors for detection of disease biomarkers, pathogens (bacteria and viruses), plant stressors, and environmental contaminants including heavy metals and disinfectants are provided. Molecular detection in biofluids, in vitro, and in vivo (small animal models and plants) are highlighted, and sensor integration into portable substrates for implantable and wearable sensing devices has been discussed. Recent advancements, which include high throughput assays and the use of machine learning models to predict more sensitive and robust sensing outcomes are discussed. Current limitations and future perspectives on translation of SWCNT optical probes into clinical practices have been provided.

Production and Characterization of GRC-SWCNT Composites for Shell Elements

Nano-sized defects in Glass fiber Reinforced Concrete (GRC) shell elements can cause damage over time, leading to mechanical and durability problems. Therefore, in this study an experimental program was conducted to investigate the application of single-walled carbon nanotube as a nano-additive material in GRC. Since there is no study on GRC-carbon nanotube (CNT) composites in the literature, the behavior of CNTs on conventional concretes was discussed. Five different GRC-SWCNT composite mixtures containing 0, 0.007, 0.010, 0.015 and 0.020 wt.% single walled carbon nanotube (SWCNT) were obtained. Calcined kaolin and acrylic polymer were used as pozzolanic and chemical modification materials in the mixtures, respectively. Workability, density, capillarity, pressure, flexural, tensile, impact, Leeb hardness and FE-SEM tests of the produced samples were carried out. According to the results obtained, the optimum SWCNT ratio in GRC mixtures was found to be 0.015 %. It was observed that there was a linear relationship between the mechanical results. FE-SEM images confirmed that SWCNTs act as bridges for micro-cracks and reinforce the microstructure.

Effects of foliar application of single-walled carbon nanotubes on carbohydrate metabolism in crabapple plants

Carbon nanotubes (CNTs) regulate growth in many plants. Carbohydrates provide energy and carbon skeleton for cell growth. However, how CNTs influence plant carbohydrate metabolism remains largely unknown. For a comprehensive understanding the response of carbohydrate metabolism and accumulation in leaves of crabapple (Malus hupehensis Rehd) to single-walled carbon nanotubes (SWCNTs), the expression of key enzymes and genes involved in apple sugar metabolism was investigated. In this report, TEM showed that SWCNTs particles were absorbed in apple leaf. Foliar application of 10 and 20 mg/L SWCNTs promoted chlorophyll content, net photosynthetic rate, stomatal conductance and transpiration rate. SWCNTs up-regulate the activity of aldose-6-phosphate reductase (A6PR), accompanied by increased concentration of photosynthetic assimilate‒sorbitol. However, the activities of sucrose phosphate synthase (SPS) and the accumulation of sucrose did not change significantly in SWCNTs-sprayed apple leaves compared with the control. In addition, the activities of photoassimilate degradation enzyme (sorbitol dehydrogenase, SDH; sucrose synthase, SUSY; neutral invertase, NINV) and hexose degradation enzyme (fructokinase, FRK; hexokinase, HK) were higher in SWCNTs-treated apple leaves than that in the control leaves. Quantitative real-time polymerase chain reaction (qRT‒PCR) results indicated that the expression of genes associated with sugar metabolism changed significantly after SWCNTs application. Taken together, we propose that spraying apple leaves with 10 and 20 mg/L SWCNTs can improve photosynthetic activity and accelerate carbohydrate metabolism in apple leaves. Our results provide insight into understanding the biological effects of CNTs in plants and are valuable for continued use of SWCNTs in agri-nanotechnology.

The effect of elution speed control on purity of separated large-diameter single-walled carbon nanotubes in gel chromatography

Large-diameter single-walled carbon nanotubes (SWNTs) have unique properties compared to small-diameter ones, for example, higher electrical conductivities, higher charge carrier mobilities, smaller bandgaps, and longer lengths, which can broaden SWNT applications. However, because the preparation methods result in mixtures of metallic SWNTs (m-SWNTs) and semiconducting SWNTs (s-SWNTs); such as in the case of small-diameter SWNTs, they must be separated and used for specific applications to obtain optimal performance characteristics. In this study, we show that simple elution speed control can increase the purity of separated large-diameter SWNTs in gel chromatography. According to the results, the flow rate of the eluant (i.e., the elution speed during gel column chromatography) greatly affects the purity of the separated m-SWNTs. We controlled the elution speed by changing the pressure inside the column during the separation process and experimentally investigated the relationship between the purity of the separated m-SWNTs and elution speed. By adjusting the elution speed to 0.13 ml/min, we obtained large quantities of pure m-SWNTs. Moreover, high-purity s-SWNTs were obtained for a wide elution speed range. Thus, highly pure m- and s-SWNTs can simultaneously be prepared by simply controlling the elution speed in single-column gel chromatography.

Distinguishing Antioxidant Molecules with Near-Infrared Photoluminescence of DNA-Wrapped Single-Walled Carbon Nanotubes.

In this study, two biomolecule solutions were distinguished using the capacity difference in the near-infrared photoluminescence (PL) of single-walled carbon nanotubes (SWNTs). Biosensing techniques using sensitive responses of SWNTs have been intensively studied. When a small amount of an oxidant or reductant solution was injected into the SWNT suspensions, the PL intensity of the SWNTs is significantly changed. However, distinguishing between different molecules remains challenging. In this study, we comparably injected saponin and banana solutions, which are known antioxidant chemicals, into an SWNT suspension. The SWNTs were solubilized by wrapping them with DNA molecules. The results show that 69.1 and 155.2% increases of PL intensities of SWNTs were observed after injection of 20 and 59 μg/mL saponin solutions, respectively. Subsequently, the increase in PL was saturated. With the banana solution, 18.1 and 175.4% increases in PL intensities were observed with 20 and 59 μg/mL banana solutions, respectively. Based on these results, the two antioxidant molecules could be distinguished based on the different PL responses of the SWNTs. In addition, the much higher saturated PL intensities observed with the banana solution suggests that the banana solution increased the capacity of the PL increase for the same SWNT suspension. These results provide helpful information for establishing biosensing applications of SWNTs, particularly for distinguishing chemicals.

(Invited, Digital Presentation) Application of Polyacid Clusters in Modifying Single-Walled Carbon Nanotubes

Phosphotungstic acids (PTAs) are a typical family of polyacids with tunable composition, structure and morphology. Relying on their super strong acidity and moderate oxidizability, they may take different roles when interacting with single walled carbon nanotubes (SWCNTs).We found that PTA could be used as stable dopants for SWCNT films to reduce the resistance without damaging the transparency. By simply dipping the SWCNT films in the solution of PTAs and drying afterwards, the sheet resistance was cut in half with long term stability. The doped films showed excellent flexibility. Both Raman spectroscopic studies and Kelvin probe force microscopy measurements revealed that the strong acidity of PTAs plays a key role in the doping effect by increasing the redox potential of the ambient O2 and thus the Fermi level of the SWCNTs is brought down.The PTA clusters can be encapsulated into the inner cavity of SWCNTs when their diameters are compatible. Such a host-guest molecular interaction between SWCNTs and inner clusters with designed size was applied to separate large-diameter s-SWCNTs. When a kind of PTA of ~1 nm in size were filled within SWCNT cavities, s-SWCNTs with diameters concentrated at ~1.3–1.4 nm were selectively extracted with the purity of ~98% by a commercially available polyfluorene derivative. The sorting mechanisms associate with oxidation effect of PTA and the size-dependent electron transfer from nanotubes to inner PTA clusters. The flexible regulation of interaction between the nanotube and clusters, thus tuning the diameter of sorted s-SWCNTs.PTAs have shown great power in tuning the properties of SWCNTs, presenting amazing potentials in the applications of SWCNTs.

New perspectives in SWCNT applications: Tuball SWCNTs. Part 1. Tuball by itself—All you need to know about it

This is not a comprehensive review on the topic of single walled carbon nanotubes (SWCNTs). Because it is very broad - a simple search on ‘carbon nanotubes’ provides well over a million citations - we are focusing on a brand of SWCNTs produced by our company, OCSiAl, trademarked as TUBALL™ or just Tuball. It is a well-known product on the market and there is a good citation record on the applications of Tuball in industry and research labs, see Fig. 1. Despite this, there is no published data in the literature properly referencing its quality and the examples of its applications are often left without sufficient characterization. Because of that, we feel that it is well overdue to have a proper summary accessible to many researchers. Besides, the beneficial properties of SWCNT augments in many applications very strongly depend on the quality of SWCNTs and the methods of their introduction into materials. We have a few successful demonstrations here, some of which have not been published yet, and a plenty of additional published results with Tuball nanotubes are included as well.

New Perspectives in SWCNT Applications: Tuball SWCNTs. Part 2. New Composite Materials through Augmentation with Tuball.

In the first part [1] we discussed the structural and physicochemical properties of single walled carbon nanotubes (SWCNTs) with the emphasis on TUBALL™ produced by OCSiAl. This part focuses on the applications of Tuball capitalizing on its unique properties. We start with discussing the methods for dispersing SWCNTs in various media suitable for maximizing their positive effect on the mechanical, electrical, and other functional properties of the composites. It follows by the examples of applications of Tuball in materials for batteries, thermosets, thermoplastics, and elastomers, most of which employ commercially produced liquid and semisolid dispersions offered by OCSiAl. This demonstrates the real versatility of Tuball augmentation for improvement of electrical and mechanical properties of various materials and should stimulate its wide application.

Development of Quality Control Methods for Dispersibility and Stability of Single-Wall Carbon Nanotubes in an Aqueous Medium.

The attractive properties of single-wall carbon nanotubes (SWCNT) such as mechanical strength and high electrical and thermal conductivity are often undercut by their agglomeration and re-agglomeration tendencies. As a result, the application of SWCNT as additives in advanced composite materials remain far from their potential, with proper dispersion being the major inhibitor. This work presents a dispersion quality control approach for water-based SWCNT dispersions (dispersed by a unique combination of physical and chemical methods), using complementary and easily scalable, characterization methods. UV-Vis spectroscopy, rheological measurements, and precipitant sheet resistance were used to understand the properties of the initial solution through processing and application. From an industrial perspective, these methods are fast and easy to measure while giving a repetitive and quick indication of dispersion quality and stability. The methods were correlated with microscopy and Raman spectroscopy to validate dispersion and SWCNT quality under various dispersing energies. The protocol was then applied to estimate the stability of SWCNT solutions, as well as the effectiveness of different surfactants in aiding dispersion. The simple, fast, and scalable combination of different characterizations provides good SWCNT dispersion and can be used as a quality control system for industrial production and usage.

Single-Chirality Near-Infrared Carbon Nanotube Sub-Cellular Imaging and FRET Probes.

Applications of single-walled carbon nanotubes (SWCNTs) in bioimaging and biosensing have been limited by difficulties with isolating single-chirality nanotube preparations with desired functionalities. Unique optical properties, such as multiple narrow near-infrared bands and several modes of signal transduction, including solvatochromism and FRET, are ideal for live cell/organism imaging and sensing applications. However, internanotube FRET has not been investigated in biological contexts. We developed single-chirality subcellular SWCNT imaging probes and investigated their internanotube FRET capabilities in live cells. To functionalize SWCNTs, we replaced the surfactant coating of aqueous two-phase extraction-sorted single-chirality nanotubes with helical polycarbodiimide polymers containing different functionalities. We achieved single-chirality SWCNT targeting of different subcellular structures, including the nucleus, to enable multiplexed imaging. We also targeted purified (6,5) and (7,6) chiralities to the same structures and observed internanotube FRET within these organelles. This work portends the use of single-chirality carbon nanotube optical probes for applications in biomedical research.

Atomistic Study of Several Peptides Covering Single‐walled Carbon Nanotube by Noncovalent Adsorption

Single-walled Carbon Nanotubes (SWNTs) have shown outstanding physicochemical, mechanical, electronic, and optical properties that enable a broad range of biomedical applications, including drug delivery (carrier for anti-cancer drugs), imaging (carrier for contrast agents), tissue engineering (bone, nerve, and cardiac), gene delivery, and biosensors. However, their carbon hexagonal-lattice nanostructure causes a sizeable surface-to-volume ratio with a potent van der Waals surface that leads to limiting characteristics for bioapplications (e.g., low solubility, agglomeration, and potential toxicity). In this perspective, the biomolecule-adsorption strategy that exhibits advantageous characteristics over covalent functionalization could not only help overcome these SWNT limitations but also preserve its pristine sp2 hybridization wall by noncovalently binding amphiphilic peptides. The objective of this computational study is to investigate the fundamental interactions and properties of ten different segments (lower than 40 amino acids) on (16,0) SWNT system using Molecular Dynamics (MD) simulations that are essential and effective factors on SWNT applications, particularly for drug delivery. This proposed coverage of natural-sequence peptides can potentially be easier recognized by biological processes as well as increase dispersibility and decrease toxicity of SWNT.

Molecular dynamics studies for enhancing the anticancer drug efficacy: Toward designing a new carbon nanotube-based paclitaxel delivery system

The promising outcomes for biological applications of single-walled carbon nanotubes (SWCNTs) including biomolecules carriers have been reported before. Therefore, the investigation of the interactions of these nano-vectors with drug molecules can provide fundamental knowledge to design appropriate SWCNT-based carriers for drug delivery purposes. The current study addressed the underlying mechanism of a widely-used anticancer drug, paclitaxel (PTX), loading on the pristine SWCNT as well as that functionalized with (-OH), (-COOH), and PW3 peptide (a biologically compatible peptide as a novel candidate for nano-carrier surface modification). The effect of the functional group of nano-carrier on the drug binding was also investigated by all-atom molecular dynamics (MD) simulations. The binding free energy calculations based on the MM-PBSA approach indicated the exothermic and spontaneous adsorption of PTX molecules onto the pristine and modified SWCNTs. The π − π stacking interactions between three separate phenyl rings of PTX and SWCNT sidewall can explain the proper drug adsorption. Moreover, remarkable differences were identified in the arrangements of the aromatic rings toward the surface of nanotubes in the four studied complexes. According to the qualitatively and quantitatively analyses, the PTX drug delivery system exhibited especial effectiveness due to the stronger interactions with the nano-carrier and more water solubility upon coupling with the PW3-functionalized SWCNT at 310 K which could be well explained by microscopic structural evaluations. For the peptide-modified SWCNT system, PTX molecules still prefer to bind the sidewall of the nano-vector rather than the peptides.

Dye Quenching of Carbon Nanotube Fluorescence Reveals Structure-Selective Coating Coverage.

Many properties and applications of single-wall carbon nanotubes (SWCNTs) depend strongly on the coatings that allow their suspension in aqueous media. We report that SWCNT fluorescence is quenched by reversible physisorption of dye molecules such as methylene blue, and that measurements of that quenching can be used to infer structure-specific exposures of the nanotube surface to the surrounding solution. SWCNTs suspended in single-stranded DNA oligomers show quenching dependent on the combination of nanotube structure and ssDNA base sequence. Several sequences are found to give notably high or low surface coverages for specific SWCNT species. These effects seem correlated with the selective recognitions used for DNA-based structural sorting of nanotubes. One notable example is that dye quenching of fluorescence from SWCNTs coated with the (ATT)4 base sequence is far stronger for one (7,5) enantiomer than for the other, showing that coating coverage is associated with the coating affinity difference reported previously for this system. Equilibrium modeling of quenching data has been used to extract parameters for comparative complexation constants and accessible surface areas. Further insights are obtained from molecular dynamics simulations, which give estimated contact areas between ssDNA and SWCNTs that correlate with experimentally inferred surface exposures and account for the enantiomeric discrimination of (ATT)4.

Length-Selective Dielectrophoretic Manipulation of Single-Walled Carbon Nanotubes.

Single-walled carbon nanotubes (SWNTs) possess unique physical, optical, and electrical properties with great potential for future nanoscale device applications. Common synthesis procedures yield SWNTs with large length polydispersity and varying chirality. Electrical and optical applications of SWNTs often require specific lengths, but the preparation of SWNTs with the desired length is still challenging. Insulator-based dielectrophoresis (iDEP) integrated into a microfluidic device has the potential to separate SWNTs by length. Semiconducting SWNTs of varying length suspended with sodium deoxycholate (NaDOC) show unique dielectrophoretic properties at low frequencies (<1 kHz) that were exploited here using an iDEP-based microfluidic constriction sorter device for length-based sorting. Specific migration directions in the constriction sorter were induced for long SWNTs (≥1000 nm) with negative dielectrophoretic properties compared to short (≤300 nm) SWNTs with positive dielectrophoretic properties. We report continuous fractionation conditions for length-based iDEP migration of SWNTs, and we characterize the dynamics of migration of SWNTs in the microdevice using a finite element model. Based on the length and dielectrophoretic characteristics, sorting efficiencies for long and short SWNTs recovered from separate channels of the constriction sorter amounted to >90% and were in excellent agreement with a numerical model for the sorting process.

Cardanol-derived cationic surfactants enabling the superior antibacterial activity of single-walled carbon nanotubes

Single-walled carbon nanotubes (SWCNTs) are potential antibacterial material, and their antibacterial activity in aqueous solutions depends on efficient surfactants to create strong interactions between well-dispersed SWCNTs and bacterial cells. Here, we designed and synthesized a new family of cationic surfactants by introducing different positively charged hydrophilic heads, i.e. –(CH2)6N+(CH3)3Br−, –(CH2)2N+(CH3)3Br− and –(CH2)2N+PyridineBr−, to cardanol obtained from cashew nut shell liquid. These surfactants can efficiently disperse SWCNTs in aqueous solutions because benzene rings and olefin chains in cardanol enable their strong π-stacking on SWCNTs. A much higher fraction of SWCNTs can be dispersed individually compared to the commonly used surfactant, dodecylbenzene-sulfonate sodium (SDBS). SWCNTs dispersed in the cardanol-derived surfactants demonstrate significantly improved antibacterial activity. At the concentration of 0.5 wt%, their minimum inhibitory concentration is 0.33 and 0.02 μg ml−1 against E. coli and S. aureus, respectively, which is only 0.8%–1.5% of that of SDBS-dispersed SWCNTs. The strong antibacterial activity can be attributed to both better dispersion of SWCNTs and positive charges introduced by hydrophilic heads, which are attracted to negatively charged bacterial cell surfaces. These cardanol-derived surfactants are promising as sustainable surfactants for enabling various SWCNT applications.

Tracing chirality, diameter dependence, and temperature-controlling of single-walled carbon nanotube non-covalent functionalization by biologically compatible peptide: insights from molecular dynamics simulations.

Biological applications of single-walled carbon nanotubes (SWCNTs), including drug delivery, require their functionalization with various functional groups such as peptides. Recently, a biologically compatible peptide (named PW3 with the sequence of NH2-Trp-Val-Trp-Val-Trp-Val-Lys-Lys-COOH) has been introduced as a good candidate for modification of carbon nanotubes due to its high affinity toward the exterior surface of these nano-carriers. In order to optimize the process of SWCNT peptide functionalization, the effects of chirality and diameter of SWCNTs as well as the temperature on PW3 adsorption were systematically investigated using molecular dynamics (MD) simulation. It was found that modification of chiral/zigzag SWCNT by PW3 peptide was more suitable compared with the armchair system due to the strong peptide-nanotube interactions and more water solubility at 310K which can be well explained by microscopic structural investigations. Regarding the enhanced peptide-chiral nanotube interactions at the low temperature of 277K, chiral nanotubes can be effective structures for SWCNT functionalization process at reduced temperatures. Our analysis indicated that disrupted PW3 and SWCNT hydration patterns and fewer internal interactions within the peptide could be responsible for the stronger peptide modification of SWCNT at higher temperatures. Additionally, "PW3/SWCNT" systems containing larger tube diameters formed more stable complexes owing to their effective surface area increment.

Comparison of cytotoxicity and membrane efflux pump inhibition in HepG2 cells induced by single-walled carbon nanotubes with different length and functional groups

Environmental risk of single-walled carbon nanotubes (SWCNTs) is receiving increasing attentions owing to their wide study and application. However, little is known on the influence of length and functional groups on SWCNT cytotoxicity. In this study, six types of SWCNTs with different functional groups (pristine, carboxyl group and hydroxyl group) and lengths (1–3 μm and 5–30 μm) were chosen. Cytotoxicities in human hepatoma HepG2 cells induced by these SWCNTs were compared based on cell viability, oxidative stress, plasma membrane fluidity and ABC transporter activity assays. Results showed that all the SWCNTs decreased cell viability of HepG2, increased intracellular reactive oxygen species (ROS) level, and damaged plasma membrane in a concentration-dependent manner. Long SWCNTs had stronger cytotoxic effects than short SWCNTs, which might be due to weaker aggregation for the long SWCNTs. Functionalization changed the toxic effects of the SWCNTs, and different influence was found between long SWCNTs and short SWCNTs. Moreover, the six types of SWCNTs at low concentrations changed plasma membrane fluidity, inhibited transmembrane ABC transporter (efflux pump) activity, and acted as chemosensitizer to improve the sensitivity of cells to arsenic, indicating the chemosensitive effect should be considered as toxic endpoint of SWCNTs. Comparison of different toxic endpoints among the six types of SWCNTs showed that short hydroxyl-SWCNT might be safer than other SWCNTs. This study provides insights into toxicities of SWCNTs, which is of great value for the risk assessment and application of SWCNTs.

(Invited) High Performance Carbon Nanotube –Laminated Perovskite Solar Cells

Recently, perovskite solar cells (PSCs) have got much attention since the big jump of the power conversion efficiency (PCE) from about 3.9% [1] to 23.3% [2] in less than a decade that is comparable to the developed Si and CIGS-based counterparts in more than 40 years. Accordingly, tremendous efforts have been devoted on increasing durability of the produced devices at low cost. PSC commonly invented by sandwiching the perovskite layers between two charge selective transport layers. Then, the two conducting electrodes are placed outside of charge selective layers, one is facing the light usually transparent conducting oxide, and the other is a noble metal like gold or silver. The metal electrode typically prepared by thermal evaporation at high vacuum level that’s substantially increase the cost as well for the cost of noble metal. Moreover, these metals either react with the PSC components or migrate into the device at environmental temperature and operational conditions that is subsequently reduces the overall performance and stability [3]. Single-walled carbon nanotubes (SWCNTs) displayed superb physical, properties in terms of conductivity, light absorption, thermal, mechanical, and chemical ones. SWCNTs could be incorporated into the PSC system [4]. SWCNTs is a favorable electrode material, owing to its abundance, hydrophobicity, and mechanical robustness [5]. The application of SWCNT as the top electrode expressively enhances the stability of PSCs by removing the ion migration, and considerably reduces the fabrication cost as it can be easily deposited onto devices by a simple mechanical transfer [6]. We recently showed that the trifillic acid-treated SWCNTs can have a great applicability with 2D/3D FACsPbI3 system reaching PCE of 17.6% with enhanced stability [7]. The conductivity of SWCNT film could be increased as the work function is tuned by using a vapor-assisted doping of trifluoromethanesulfonic acid (TFMS). We extend this work on the MAPbI3 system showing better performance. In this presentation, we will present our latest results on doping of SWCNT electrodes with diluted solution of TFMS having a new record of PCE for the SWCNT-based PSCs. Our devices showed higher PCE of more than 18 % with a J SC of 22.67 mA cm-2, V OC of 1.104 V, and FF of 0.724 through the optimization of hole transport layer concentration as shown in figure 1. Additionally, we will show the possibility of introducing our new 1D heterostructures by wrapping of various SWCNT with BN and TMD layers using chemical vapor deposition into the solar cells and devices field. These SWCNT-based heterostructures are expected to have a broad interest and impact in fabricating BN-protected or gated SWNT devices and building more sophisticated 1D material systems [8]. These new structures are expected to give extra functionality, durability, and great applicability in electronic, optoelectronic, and energy devices.

Comparison of mode-locking regimes in a holmium fibre laser

A comparison has been performed for two mode-locking regimes in an all-fibre holmium laser: locking due to nonlinear polarisation rotation (NPR) and hybrid mode-locking (NPR with application of single-walled carbon nanotubes). The characteristics of pulsed lasing in both regimes are investigated. Pulsed lasing is obtained at wavelengths of 2072 and 2082 nm, with FWHM values of 3.7 and 3.3 nm, respectively. The pulse width in both cases does not exceed 1.5 ps. The pulse energies in the NPR mode-locking and hybrid mode-locking regimes are 0.4 and 0.3 nJ, respectively. It is shown that the signal-to-noise ratio in the case of hybrid mode-locking is 3 dB better than that implemented under conditions of NPR mode-locking. A possibility of self-starting a laser system by applying hybrid mode-locking is indicated.