Properties Of Single-walled Carbon Nanotubes Research Articles

(Invited, Digital Presentation) Optoelectronic Processes in Single-Chirality Carbon Nanotube Thin Films

Much understanding exists regarding chirality-dependent properties of single-wall carbon nanotubes (SWCNTs), primarily obtained through single-tube studies. However, macroscopic manifestations of chirality dependence have been limited, especially in electronic transport. Here, recent progress in our optical and electronic transport studies of single-chirality SWCNT thin films will be reviewed. We observed pronounced chirality-dependent electronic localization in temperature and magnetic field dependent conductivity measurements on macroscopic films of single-chirality SWCNTs [1]. We also performed optical absorption measurements in aligned single-chirality (6,5) SWCNT films, and through comparison with detailed theoretical calculations based on the Boltzmann scattering equation, we demonstrated that the background absorption is due to phonon-assisted transitions from the semiconductor vacuum to finite-momentum continuum states of excitons [2]. Furthermore, we conducted terahertz emission and photocurrent studies on films of aligned single-chirality semiconducting SWCNTs and found that excitons autoionize, i.e., spontaneously dissociate into electrons and holes [3]. Some of these studies were enabled by our recent improvement of the controlled vacuum filtration technique [4,5], which allows us to fabricate wafer-scale aligned SWCNTs with extremely anisotropic optical properties [6-9]. W. Gao et al., “Band Structure Dependent Electronic Localization in Macroscopic Films of Single-Chirality Single-Wall Carbon Nanotubes,” Carbon 183, 774 (2021).S. Dal Forno et al., “Origin of the Background Absorption in Carbon Nanotubes: Phonon-Assisted Excitonic Continuum,” Carbon 186, 465 (2021).F. R. G. Bagsican et al., “Terahertz Excitonics in Carbon Nanotubes: Exciton Autoionization and Multiplication,” Nano Letters 20, 3098 (2020).X. He et al., “Wafer-Scale Monodomain Films of Spontaneously Aligned Single-Walled Carbon Nanotubes,” Nature Nanotechnology 11, 633 (2016).W. Gao and J. Kono, “Science and Applications of Wafer-Scale Crystalline Carbon Nanotube Films Prepared through Controlled Vacuum Filtration,” Royal Society Open Science 6, 181605 (2019).F. Katsutani et al., “Direct Observation of Cross-Polarized Excitons in Aligned Single-Chirality Single-Wall Carbon Nanotubes,” Physical Review B 99, 035426 (2019).W. Gao et al., “Macroscopically Aligned Carbon Nanotubes as a Refractory Platform for Hyperbolic Thermal Emitters,” ACS Photonics 6, 1602 (2019).N. Komatsu et al., “Groove-Assisted Global Spontaneous Alignment of Carbon Nanotubes in Vacuum Filtration,” Nano Letters 20, 2332 (2020).A. Baydin et al., “Giant Terahertz Polarization Rotation in Ultrathin Films of Aligned Carbon Nanotubes,” Optica 8, 760 (2021).

(Invited) Design of Robust Multiplexed Optical Nanosensors for In Vivo Disease Detection

The rapid, minimally-invasive detection of diverse analytes in vivo remains a goal for the diagnosis of cancer and related diseases. Toward this end, we are designing nanosensors based on the optical properties of single-walled carbon nanotubes (SWCNT) for use both in patients and at the bedside. SWCNT fluorescence is in the near-infrared window for biological imaging, is stable upon laser excitation, and responds rapidly to changes in its local environment. We are approaching the design of multiplexed implantable biomarker sensors through several routes, including developing novel bioconjugate chemistry approaches to antibodies and other molecular recognition elements to improve sensitivity of the sensors. We are also evaluating molecular tools to screen non-specific interactions within the local environment, improving the selectivity of these sensors. In parallel, we are using aqueous two-phase extraction (ATPE) methods to allow for separation of single-chirality SWCNT prior to bioconjugate chemistry approaches, allowing for specific detection of multiple analytes at once. Finally, we are exploring various hydrogel systems to allow for their immobilization upon injection into living systems and repeated monitoring of local biomarker concentrations. We expect these approaches to further bridge the translation of sensor devices toward clinical diagnostic tools. We hope to deploy SWCNT-based sensors to detect disease at early stages, evaluate disease response to treatment, and monitor disease progression. These aims will allow physicians to make rapid, informed decisions on patient prognosis and treatment.

(Invited) Thermoexcitonic Properties of Carbon Nanotubes

Single-walled carbon nanotubes (SWCNTs) are representative low dimensional nanomaterials showing various intriguing excitonic properties [1-7]. Owing to the large binding energy of quasi one-dimensional excitons on the order of 0.3-0.5 eV, many of the excitonic phenomena can be observed even at elevated temperatures, which is opening up unprecedented applications of excitons in energy science and thermal engineering. I will discuss our recent progress in the studies on the excitonic thermal light emission properties of SWCNTs and their application in heat-to-light energy conversion devices. [1] Y. Miyauchi et al., Nat. Photonics 7, 715 (2013). [2] N. Akizuki, Y. Miyauchi et al., Nat. Commun. 6, 8920 (2015). [3] Y. Miyauchi et al., Phys. Rev. B, 92, 205407(2015). [4] A. Takakura, Y. Miyauchi et al., Nat. Commun. 10, 3040 (2019). [5] T. Nishihara, Y. Miyauchi et al., Nat. Commun. 9, 3144 (2018). [6] S. Konabe, T. Nishihara, Y. Miyauchi, Opt. Lett. 46, 3021 (2021). [7] T. Nishihara, Y. Miyauchi et al., submitted.

(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.

Size and displacement combining detection on physics properties of carbon nanotubes using a proposed energy approach

In this paper, a coupling of advanced molecular structural model with energy method is developed to calculate the mechanical properties of single-walled carbon nanotubes (SWCNTs). The energy of a system is expressed by an advanced force field of molecular mechanics. Under the assumption of a small deformation and the principle of minimum potential energy, closed form formations are derived for temperature-dependent Young's modulus, Poisson's ratio, and bulk modulus, which are the functions of the length of C-C bonds and the out-plane displacement. The results show that the effects of tube diameter and out-plane displacement on the elastic properties of carbon nanotubes is significant when the tube diameter is small. Moreover, the principle of force-heat equivalent energy density (FHEED) is applied to describe the strain-dependent energy density 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.

Performance Evaluation of CNTFETs Fabricated with Carbon Nanotubes of Different Synthesis Methods

Single walled carbon nanotubes (SWCNTs) exhibit extraordinary electronic properties that render it as an exciting candidate to be applied as the active channel of high-performance carbon nanotube field effect transistors (CNTFETs). The electronic properties of SWCNTs have been demonstrated to be dependent on the tube intrinsic properties that includes structural defects, chirality and diameter. Structural tube defects can be affected by the synthesis method and therefore the latter should also affect the device performance. Hence, this paper aims to present the influence of SWCNTs source synthesis method towards the resulting CNTFET device characteristics. A total of four SWCNT samples were sourced from different synthesis methods in fabricating CNTFETs. The synthesis methods are arc-discharge and three different variation of chemical vapor deposition (CVD) processes, which are DIPS, HiPco and CoMoCAT, respectively. Prior to fabrication, the SWCNT samples were characterized via Raman spectroscopy to quantifythe tube defect levels of each sample, which are directly proportional to the G-peak to D-peak height ratio, G/D. Electrical characterization was carried out via 3-terminal field effect I-Vmeasurement to evaluate key device performance parameters such ason-off current ratio, ION/IOFF, transconductance, gm,subthreshold slope, Spand field effect mobility, μFE.Analysis shows that G/Daffects the IOFFmore significantly relative to ION, resulting in increasing ION/IOFF, and hence switching performance, when G/Dincreases. It is shown an increase of ~50% to the G/Dof the SWCNT source resulted in ~ 860% increase in μFE. Based on the correlation between the optical analysis and electrical measurement, weconclude that theSWCNT growth method cansignificantly affectthe CNTFET device performance.

Influence of defects on the static and dynamic buckling behavior of single-wall carbon nanotubes via molecular dynamics method

Carbon nanotubes (CNTs) exhibit often various defects during the preparation process. Thus, a detailed understanding of the impact of defects on the mechanical properties of CNTs is essential for the design of both CNTs devices and composites. Along these lines, in this work, the effects of two common defects (vacancy and Stone-Wales) on static buckling and dynamic vibration properties of single-walled carbon nanotubes (SWCNTs) are investigated. Firstly, the formation energies of single vacancy defects and Stone-Wales (S-W) defects are studied by molecular dynamics (MD), while the impact of these two defects on the compression performance and natural frequency properties of SWCNTs are explored. Secondly, the axial vibration properties of SWCNTs are studied by using the nonlocal elastic theory and the influence of defects on the dynamic axial displacement of SWCNTs under different aspect ratio is also studied. Moreover, through the change of axial displacement, the change trend of SWCNTs natural frequency with the change of aspect ratio is predicted. The results show that SWCNTs with larger aspect ratios are more prone to defects and its natural frequency will decreases. The study also found that the existence of defects will reduce the buckling properties and vibration characteristics of SWCNTs, and the impact of the S-W defect on the axial mechanical properties of SWCNTs are greater than that of the vacancy defect.

Functionalization of Pristine, Metallic, and Semiconducting-SWCNTs by ZnO for Efficient Charge Carrier Transfer: Analysis through Critical Coagulation Concentration.

Noncovalent functionalization of single-walled carbon nanotubes (SWCNT) by semiconducting oxides is a majorly sought technique to retain individual properties while creating a synergetic effect for an efficient heterostructure charge transfer. Three types of electronically and optically different SWCNTs: metallic (m), semiconducting (s), and pristine (p) are functionalized by ZnO using a facile sonication method. The physicochemical and morphological properties of the ZnO-functionalized SWCNTs, m-SWCNT+ZnO, s-SWCNT+ZnO, and p-SWCNT+ZnO, are analyzed by advanced characterization techniques. Evidence of charge transfer between SWCNT and ZnO is observed with an increase in charge carrier lifetime from 3.31 ns (ZnO) to 4.76 ns (s-SWCNT+ZnO). To investigate the optimum interaction between SWCNTs and ZnO, critical coagulation concentrations (CCC) are determined using UV–vis absorption spectroscopy for m-SWCNT, s-SWCNT, and p-SWCNT using different molar concentrations of ZnO as the coagulant. The interaction and coagulation mechanisms are described by the modified DLVO theory. Due to the variation in dielectric values and electronic properties of SWCNTs, the CCC values obtained have differed: m-SWCNT (1.9 × 10–4), s-SWCNT (3.4 × 10–4), and p-SWCNT (2 × 10–4). An additional analysis of the aggregates and supernatants of the CCC experiments is also shown to give an insight into the interaction and coagulation processes, explaining the absence of influence exerted by sedimentation and centrifugation.

First-principles study on electronic and optical properties of single-walled carbon nanotube under an external electric field.

In this study, the electronic and optical properties of one-dimensional (1D) single-walled carbon nanotube (SWCNT) nanostructures, and under the external electric field [Formula: see text] applied in the z-direction, are investigated using density functional theory (DFT) calculations. The applied [Formula: see text] leads to significant modulation of the bandgap and changes the total density of states (TDOS), partial density of states (PDOS), absorption coefficient, dielectric function, optical conductivity, refractive index, and the loss function. The application of the [Formula: see text] on the SWCNT/Carboxyl structure leads to tighten its bandgap. The peaks of TDOS around the Fermi level are very weak. The absorption coefficient increases in visible range and decreases in ultraviolet (UV) domain proportionally with the [Formula: see text]. It is found that electronic structures and optical properties of the SWCNT/Carboxyl could be affected by the [Formula: see text]. All these results provide the important information for understanding and controlling the electronic and optical properties of 1D crystals by the [Formula: see text]. This study establishes a theoretical foundation for our future experimental work regarding optoelectronic properties of the SWCNT/Carboxyl material.

Structural properties of single-walled carbon nanotubes under extreme dynamic pressures

The structural behaviors of single-walled carbon nanotubes (SWNTs) along the radial direction are critical to the cross-sectional phase transition, elastic recovery, and band structure engineering. Previous static pressure studies have established a clear picture on the structural behaviors of SWNTs that governed by the Lévy-Carrier law. But when the pressurization becomes dynamic, there lacks a fundamental understanding of the structural properties of SWNTs along the radial direction. Here, different from static (< 1 GPa/s) and shock compression (> 107 GPa/s), we gain new insights on the phase transition, recovery dynamics and energy dissipation of SWNT bundles with a median diameter of dt ∼1.4 and ∼0.8 nm under modest dynamic pressures in two common pressure mediums (4:1 methanol-ethanol mixture, silicone oil). Upon single ramp compression (ramp rate in an order of magnitude of ∼10–103 GPa/s), the lineshape and intensity changes of Raman spectra induced by the dynamic effect of hydrostatic stress are commonly observed, suggesting different structural behaviors compared with static pressure results. Unexpectedly, the pressure-induced defects are not found in cyclic ramp compressions up to 105 cycles, showing high structural stability to dynamic loading. The corresponding recovery dynamics and energy dissipation mechanism of SWNTs under varying dynamic conditions are also discussed. By analyzing the shear strain potential, distinct dynamic effects of hydrostatic pressure on the SWNTs in two pressure mediums are quantitatively unveiled.

Influence of Gamma Irradiation on the Properties of Single-Walled Carbon Nanotubes Obtained by CVD Synthesis

Influence of Gamma Irradiation on the Properties of Single-Walled Carbon Nanotubes Obtained by CVD Synthesis

Quantification and removal of carbonaceous impurities in a surfactant-assisted carbon nanotube dispersion and its implication on electronic properties.

Carbonaceous impurities (CIs) affect the optoelectronic properties as well as the ability to use absorption spectroscopy to estimate the metallic content of a single-walled carbon nanotube (SWNT) dispersion. Therefore, a method for the accurate quantification and removal of CIs is required. We have devised methods to characterize and quantify CIs present in SWNT batches and to determine the effects of CIs on the optical and electrical properties of SWNT. Quantitative determination of CIs stems from the finding that chloroform selectively disperses CIs present in SWNT batches. CIs separated by dispersing the as-purchased SWNT batch in chloroform have the morphology of defective and agglomerated few-layered graphenes, whose sizes and locations depend on SWNT batches. Moreover, CIs exhibit a featureless UV-vis-mid-wavelength IR (MWIR) absorption curve and an extinction coefficient comparable to graphenes and show difference with carbon black, which is frequently used as the CI reference. The MWIR region that shows least absorptions caused by the transition of various SWNT types was utilized to assess the significant contribution made by CIs present in a surfactant-assisted SWNT dispersion, showing about 12–19 wt% of CIs in various SWNT dispersions. In addition, the extraction of CIs with chloroform results in a highly purified SWNT batch without any diameter distribution change originating from oxidative damage as compared to the commercially available purified SWNT batch. Finally, we found that increasing the weight of CIs present in a SWNT dispersion strongly lowers the thermal conductivity of a SWNT film when compared with the electrical conductivity. This study provides a way to understand the negative effects that CI has on the optoelectronic properties of SWNTs as well as the beneficial effects of excluding ubiquitous CIs in SWNTs batches.

Amperometric sensor for the detection of hydrogen stable isotopes based on Pt nanoparticles confined within single-walled carbon nanotubes (SWNTs)

The development of hydrogen-based energy and nuclear energy requires new sensing material and high-performance gas sensor for hydrogen stable isotopes, hydrogen (H2) and deuterium (D2). Amperometric gas sensors based on SWNT-filled Pt composite material (Pt-SWNT-in) to combine the good electronic properties of SWNTs and space-confined effect of Pt catalyst have been investigated for detecting H2 and D2. The Pt-SWNT-in electrode shows an excellent linear response in a wide range of 160–8000 ppm hydrogen in N2 atmosphere with the correlation coefficient of 0.9993, and compared to the electrode with Pt nanoparticles supported outside of SWNTs, its sensitivity per Pt loading is 3 times, moreover, it gives larger response current for detection of H2 in air and D2 in N2 atmosphere. Additionally, the Pt-SWNT-in electrode provides a response current to deuterium 0.9 times that to hydrogen in N2. The results present the Pt-SWNT-in electrode with superior sensitivity, selectivity, stability and a response variation for detection of hydrogen and deuterium, which would take advantage of the space-confined effect of SWNTs on Pt catalysts to enhance the sensor performance for detecting hydrogen stable isotopes, and provide an approach to discriminate between hydrogen and deuterium.

N-doped direction-dependent electronic and mechanical properties of single-walled carbon nanotube (SWCNT) from a first-principles density functional theory (DFT) and MD-simulation

In this paper, the electronic and mechanical properties of Nitrogen (N) doped (6,1) single walled carbon nanotube (SWCNT) is analysed based on the first principles density functional theory (DFT) and Molecular dynamic (MD) calculation. A systematic N-doping on SWCNT was performed along zigzag (zz) and armchair (ac) direction, where the armchair doping is parallel to tube axis while zigzag is along the cross-section perpendicular to tube axis. The zz and ac doping resulted in variations in the electronic properties of the even and odd number of N-dopant atoms. To evaluate the mechanical properties, ab − initio MD-simulations was carried out. We found a dependence of the tensile response of the tube on the dopant concentration and doping pattern. Single N-doped system show enhanced tensile stress by 55% as compared to the pristine SWCNT with marginal changes in the young's modulus for all N-doped systems.

Aqueous two-phase extraction of single-walled carbon nanotubes using nonionic surfactant Tween 60

<p indent="0mm">Due to its excellent electronic and optical properties, single-walled carbon nanotubes (SWNTs) have attracted extensive attention. Since the property of SWNTs is determined by their structures, applications like high-performance devices require SWNTs with identical structures and uniform properties. Therefore, the sorting of SWNTs is of great significance. Aqueous two-phase (ATP) extraction is an emerging method that can be utilized to realize the structure sorting of SWNTs. ATP extraction is a repeatable and reliable technique that does not require state-of-the-art equipment. It is efficient and easy to scale up. In this article, by adjusting the concentration of sodium deoxycholate (DOC) and nonionic surfactant Tween 60, the diameter sorting of SWNTs and the separation of high purity (6,5) tubes were achieved. The sorting can be carried out at a higher DOC concentration, which could improve the competitive coating between DOC and Tween 60 on the surface of SWNTs, and further improve the sorting efficiency of the co-surfactant system. The comparison of the separation results between the Tween 60-DOC surfactant system and the SDS-DOC surfactant system shows that the introduction of nonionic surfactant Tween 60 is beneficial to the separation of higher purity (6,5) tubes.

Finite element framework for static analysis of temperature dependent IHSDT based functionally graded CNT reinforced plates

In this study, a finite element model is presented to investigate the effect of temperature dependent material properties of single-walled carbon nanotube (SWCNT) and PMPV on the static response of functionally graded carbon-nano tube reinforced (FG-CNTR) plate with four different boundary conditions. The governing equations are developed on the basis of inverse hyperbolic shear deformation theory (IHSDT) and Hamilton’s principle. The effective material properties are evaluated using the extended rule of mixture. The pattern of CNTs distribution in the plate is assumed to be uniformly distributed (UD) and functionally graded (FG-V, FG-Λ, FG-O, and FG-X) along the thickness direction. The governing equations are solved using a C0 isoparametric finite element method (FEM) and discretized with an isoparametric eight noded element with seven degrees of freedom per node. The authors have performed various parametric studies to observe the effect of plate span to thickness ratio, volume fraction, CNTs distribution on the static response of FG-CNTR plate subjected to sinusoidal (SSL) and uniformly distributed (UDL) loading conditions. The numerical solutions for the deflection and stresses are obtained and compared with known results in the literature. The study concludes that IHSDT accurately predicts the behavior of the FG-CNTR plate, also temperature dependent material properties have significantly influenced the static behavior of the FG-CNTR plate.

The role of topological defects on the mechanical properties of single-walled carbon nanotubes

ABSTRACT Carbon nanotubes (CNTs) are among the most employed nanomaterials in developing new technologies. Their applicability requires a fundamental understanding of the chirality and defect effects on the mechanical properties. In this study, molecular dynamics (MD) simulations were performed to investigate the mechanical response of defective single-walled carbon nanotubes (SWCNTs) under tension loading. The Stones-Wales, monovacancy, and the divacancy reconstructions (585, 555777, and 555567777) defects were considered. In addition, we investigated the influence of the adaptive intermolecular reactive bond order (AIREBO) potential cut-off radii on the defect formation energy of SWCNTs. Our results reveal that the tensile strength properties are notably dependent on the chirality and defect configurations at strains over 8%. Energetically favourable defects have a high impact on the mechanical response of SWCNTs. A combination of certain defects may lead the control on the fracture pattern of the SWCNTs, which can significantly contribute to the designing of innovative nanostructures with tailored properties.

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.

Nickelocene-Filled Purely Metallic Single-Walled Carbon Nanotubes: Sorting and Tuning the Electronic Properties.

We conducted the filling of single-walled carbon nanotubes (SWCNTs) with nickelocene molecules and separation of the filled SWCNTs by conductivity type by density-gradient ultracentrifugation. We tailored the electronic properties of nickelocene-filled purely metallic SWCNTs by thermal treatment in high vacuum. Our results demonstrated that annealing at low temperatures (360–600 °C) leads to n-doping of SWCNTs, whereas annealing at high temperatures (680–1200 °C) results in p-doping of SWCNTs. We found a correlation between the chemical state of the incorporated substances at different annealing temperatures and its influence on the electronic properties of SWCNTs.