Semiconducting Single-walled Carbon Nanotubes Research Articles

Films enriched with semiconducting single-walled carbon nanotubes by aerosol N2O etching

Semiconducting single-walled carbon nanotubes (SWCNTs) are of particular interest to electronics. As most of synthesis methods yield 1/3 of metallic SWCNTs, the route for a purely semiconducting species is a complex multistep procedure. Herein, we report a simple one-step method for selective etching of metallic SWCNTs in the aerosol phase with nitrous oxide. Our approach is based on a tandem of two flow reactors, where the first one is needed to produce individual SWCNTs, and the second one is to eliminate metallic SWCNTs due to their faster oxidization rate. The oxidant (N2O) adsorption on the SWCNT surface was modelled by DFTB taking into account geometric characteristics of the nanotube and its electronic properties, resulting in less N2O adsorption energy for metallic SWCNTs of some chiralities than for semiconducting ones. Thus, we obtained SWCNT films enriched with semiconducting nanotubes up to optical selectivity of 97% by treatment of pristine SWCNT aerosols for 6 s at 600 °C in an atmosphere of 30% N2O. The treated films show a turnaround of the temperature dependence of the resistance. As a proof of the concept, enriched SWCNT films were utilized as a channel material for thin film field effect transistors, which show an average improvement of ON/OFF current ratio from 1- 10 to 10 - 104 for the same open state resistance for the statistical sampling based on more than 7500 devices.

Investigating Charge Transport in Semiconducting Single‐Walled Carbon Nanotube Networks by Charge Modulation Microscopy

AbstractSolution‐processed networks of semiconducting single‐walled carbon nanotubes (SWCNTs) hold promise as active layers for large‐scale digital circuits, thermoelectric devices, and healthcare applications. Yet, the combined effects of local network properties and (n,m) species composition need to be addressed to improve the performance and reproducibility of state‐of‐the‐art devices. Charge modulation microscopy (CMM) is used to investigate charge transport in field‐effect transistors (FETs) based on monochiral (6,5) SWCNT networks and multichiral networks containing five semiconducting SWCNT species with different band gaps. By mapping the charge‐modulated signal within the FET channel with sub‐micrometer resolution, the spatial distribution of free carriers and its evolution during the switching of the FET are revealed. The CMM maps provide direct evidence that holes and electrons are transported preferentially through the same percolation paths. A moderate positive correlation between the SWCNT density in the monochiral (6,5) network and the charge density in subthreshold regime is demonstrated. In multichiral networks, the charge transport paths are on average less fragmented when involving low band gap species. CMM emerges as a valuable technique to estimate the size of preferential percolation domains associated with the average distance traversed by charge carriers on SWCNTs of the same chirality before tunneling onto other species.

Near‐Intrinsic Photo‐ and Electroluminescence from Single‐Walled Carbon Nanotube Thin Films on BCB‐Passivated Surfaces

AbstractTheir outstanding electrical and optical properties make semiconducting single‐walled carbon nanotubes (SWCNTs) highly suitable for charge transport and emissive layers in near‐infrared optoelectronic devices. However, the luminescence spectra of SWCNT thin films on commonly used glass and Si/SiO2 substrates are often compromised by broadening of the main excitonic emission and unwanted low‐energy sidebands. Surface passivation with a commercially available, low dielectric constant, cross‐linked bis‐benzocyclobutene‐based polymer (BCB) enhances the emission properties of SWCNTs to the same level as hexagonal boron nitride (h‐BN) flakes do. The presence of BCB suppresses sideband emission, especially from the Y1 band, which is attributed to defects introduced by the interaction of the nanotube lattice with oxygen‐containing terminal groups of the substrate surface. The facile and reproducible deposition of homogeneous BCB films over large areas combined with their resistance against common solvents and chemicals employed during photolithography make them compatible with standard semiconductor device fabrication. Utilizing this approach, light‐emitting (6,5) SWCNT network field‐effect transistors are fabricated on BCB‐treated glass substrates with excellent electrical characteristics and near‐intrinsic electroluminescence. Hence, passivation with BCB is proposed as a standard treatment for substrates used for spectroscopic investigations of and optoelectronic devices with SWCNTs and other low‐dimensional emitters.

Short bandgap of porphyrin molecules (Py) filled in a semiconducting single-walled carbon nanotube (Py@NT17) for highly efficient organic photovoltaic cells

In this paper, the porphyrin (Py) molecule, which is filled in the semiconducting single-walled carbon nanotube (SWNT) known as CNT17, is investigated. We have calculated the optoelectronic characteristics of two configurations of the hybrid system with a single Py molecule filled into CNT17 (Py@CNT17 and Py2@CNT17) using density functional theory (DFT). According to the investigation’s findings, a charge transfer occurred between the Py molecules and the CNT17 nanotube, confirming the stability of the structure. As determined by the electronic calculation, we discovered that the rise in the fermi energy position of CNT17 after encapsulation, suggests a CT connection between Py and CNT17.

Design Optimization and Characterization with Fabrication of Nanomaterials-Based Photo Diode Cell for Subretinal Implant Application.

An ultrathin nano photodiode array fabricated in a flexible substrate can be an ideal therapeutic replacement for degenerated photoreceptor cells damaged by Age-related Macula Degeneration (AMD) and Retinitis Pigmentosa (RP), such as retinal infections. Silicon-based photodiode arrays have been attempted as artificial retinas. Considering the difficulties caused by hard silicon subretinal implants, researchers have diverted their attention towards organic photovoltaic cells-based subretinal implants. Indium-Tin Oxide (ITO) has been a favorite choice as an anode electrode. A mix of poly(3-hexylthiophene) and [6,6]-phenyl C61-butyric acid methyleste (P3HT: PCBM) has been utilized as an active layer in such nanomaterial-based subretinal implants. Though encouraging results have been obtained during the trial of such retinal implants, the need to replace ITO with a suitable transparent conductive electrode will be a suitable substitute. Further, conjugated polymers have been used as active layers in such photodiodes and have shown delamination in the retinal space over time despite their biocompatibility. This research attempted to fabricate and characterize Bulk Hetero Junction (BHJ) based Nano Photo Diode (NPD) utilizing Graphene-polyethylene terephthalate (G-PET)/semiconducting Single-Wall Carbon Nano Tubes (s-SWCNT): fullerene (C60) blend/aluminium (Al) structure to determine the issues in the development of subretinal prosthesis. An effective design approach adopted in this analysis has resulted in developing an NPD with an Efficiency of 10.1% in a non-ITO-driven NPD structure. Additionally, the results show that the efficiency can be further improved by increasing active layer thickness.

Impact of Dielectric Environment on Trion Emission from Single-Walled Carbon Nanotube Networks.

Trions are charged excitons that form upon optical or electrical excitation of low-dimensional semiconductors in the presence of charge carriers (holes or electrons). Trion emission from semiconducting single-walled carbon nanotubes (SWCNTs) occurs in the near-infrared and at lower energies compared to the respective exciton. It can be used as an indicator for the presence of excess charge carriers in SWCNT samples and devices. Both excitons and trions are highly sensitive to the surrounding dielectric medium of the nanotubes, having an impact on their application in optoelectronic devices. Here, the influence of different dielectric materials on exciton and trion emission from electrostatically doped networks of polymer-sorted (6,5) SWCNTs in top-gate field-effect transistors is investigated. The observed differences of trion and exciton emission energies and intensities for hole and electron accumulation cannot be explained with the polarizability or screening characteristics of the different dielectric materials, but they show a clear dependence on the charge trapping properties of the dielectrics. Charge localization (trapping of holes or electrons by the dielectric) reduces exciton quenching, emission blue-shift and trion formation. Based on the observed carrier type and dielectric material dependent variations, the ratio of trion to exciton emission and the exciton blue-shift are not suitable as quantitative metrics for doping levels of carbon nanotubes.

Semiconducting SWCNT Photo Detector for High Speed Switching Through Single Halo Doping

The method opted for accuracy, and no existing studies are based on this method. A design and characteristic survey of a new small band gap semiconducting Single Wall Carbon Nano Tube (SWCNT) Field Effect Transistor as a photodetector is carried out. In the proposed device, better performance is achieved by increasing the diameter and introducing a new single halo (SH) doping in the channel length of the CNTFET device. This paper is a study and analysis of the performance of a Carbon Nano Tube Field Effect Transistor (CNTFET) as a photodetector using the self-consistent Poisson and Green function method. The 2D self-consistent Poisson and Green’s function method for various optical intensities and wavelength simulate this proposed photodetector. The performance study is based on the simulation of drain current, transconductance, sub-threshold swing, cut-off frequency, gain, directivity, and quantum efficiency under dark and illuminated conditions. These quantum simulation results show that cut-off frequency increases while there is an increase in diameter. The proposed SH-CNTFET provides better performance in terms of higher gain and directivity than conventional CNTFET (C-CNTFET). This device will be helpful in optoelectronic integrated circuits (OEIC) receivers due to its superior performance.

Understanding Oligonucleotide Hybridization and the Role of Anchoring on the Single-Walled Carbon Nanotube Corona Phase for Viral Sensing Applications

Semiconducting single-walled carbon nanotubes (SWCNTs) with tailored corona phases (CPs), or surface-adsorbed molecules, have emerged as a promising interface for sensing applications. The adsorption of an analyte can be specifically transduced as a modulation of their band-gap near-infrared (nIR) photoluminescence (PL). One such CP ideal for this purpose is single-stranded DNA (ssDNA), where subsequent sequence-dependent hybridization can result in PL emission wavelength shifts. Due to ssDNA adsorption to the SWCNT surface, the resultant noncanonical hybridization and its effect on SWCNT photophysical properties are not well understood. In this work, we study 20- and 21-mer DNA and RNA hybridization on the complementary ssDNA-SWCNT CP in the context of nucleic acid sensing for SARS-CoV-2 sequences as model analytes. We found that the van’t Hoff transition enthalpy of hybridization on SWCNT CP was −11.9 kJ mol–1, much lower than that of hybridization in solution (−707 kJ mol–1). We used SWCNT solvatochromism to calculate the solvent-exposed surface area to indicate successful hybridization. We found that having a 30-mer anchor region in addition to the complementary region significantly improved PL response sensitivity and selectivity, with a (GT)15 anchor preferred for RNA targets. Coincubation of ssDNA-SWCNTs with an analyte at 37 °C resulted in faster hybridization kinetics without sacrificing specificity. Other methods aimed to improve CP rearrangement kinetics such as bath sonication and surfactant additions were ineffective. We also determined that the target sequence choice is important as secondary structure formation in the target is negatively correlated with hybridization. Best-performing CPs showed detection limits of 11 and 13 nM for DNA and RNA targets, respectively. Finally, we simulated sensing conditions using the saliva environment, showing sensor compatibility in biofluids. In total, this work elucidates key design features and processing to enable sequence-specific hybridization on ssDNA-SWCNT CPs.

Comprehensive Model for the Thermoelectric Properties of Two-Dimensional Carbon Nanotube Networks

Networks of semiconducting single-walled carbon nanotubes (SWCNTs) are interesting thermoelectric materials due to the interplay between CNT and network properties. Here, we present a unified model to explain charge and energy transport in SWCNT networks. We use the steady-state master equation for the random resistor network containing both intra- and intertube resistances, as defined through their one-dimensional density of states that are modulated by static Gaussian disorder. The tube-resistance dependence on the carrier density and disorder is described through the Landauer formalism. Electrical and thermoelectric properties of the network are obtained by solving Kirchhoff's laws through a modified nodal analysis, where we use the Boltzmann-transport formalism to obtain the conductivity, Seebeck coefficient, and electronic contribution to the thermal conductivity. The model provides a consistent description of a wide range of previously published experimental data for temperature and charge-carrier-density-dependent conductivities and Seebeck coefficients, with energetic disorder being the main factor to explain the experimentally observed mobility upswing with carrier concentration. Moreover, we show that, for lower disorder energies, the Lorentz factor obtained from the simulation is in accordance with the Wiedemann-Franz law for degenerate-band semiconductors. At higher disorder, deviations from simple band behavior are found. Suppressed disorder energy and lattice thermal conductivity can be the key to higher thermoelectric figures of merit, zT, in SWCNT networks, possibly approaching or even exceeding zT = 1. The general understanding of transport phenomena will help the selection of chirality, composition, and charge-carrier density of SWCNT networks to improve their efficiency of thermoelectric energy conversion.

Comparison of thermoelectric properties of sorted and unsorted semiconducting single-walled carbon nanotube free-standing sheets

Semiconducting single-walled carbon nanotubes (s-SWCNTs) are promising materials for thermoelectric generation (TEG) because of their large theoretical Seebeck coefficient (S). In this study, to discuss superiority of s-SWCNTs for TEG devices, thermoelectric properties of free-standing s-SWCNT sheets were compared with unsorted SWCNT sheets. To obtain the highest power density, the films were doped with triethyloxonium hexachloroantimonate and 2-(2-methoxyphenyl)-1,3-dimethyl-2,3-dihydro-1H-benzo[d]imidazole as the hole and electron dopants, respectively. The doped s-SWCNT sheets exhibited higher S but lower electrical conductivity than those of the unsorted SWCNT sheets. Consequently, the power factor of the s-SWCNT sheets was lower than that of the unsorted SWCNT sheets.

Localized Charge on Surfactant-Wrapped Single-Walled Carbon Nanotubes

As-synthesized, semiconducting single-walled carbon nanotubes (SWCNTs) are nominally charge neutral. However, ionic surfactants that are commonly used to disperse SWCNTs in solution can lead to significantly charged aggregates adsorbed to the nanotube. Here, electrostatic force microscopy (EFM) was used to characterize the static-charge interactions between individual SWCNTs and the local environment. We report nonuniform spatial charge distributions with highly varying magnitudes ranging between ±15 e associated with surfactant coverage on long SWCNTs (>1.5 μm). EFM images acquired after resonant photoexcitation demonstrate charge carrier localization due to electrostatic interactions with charged surfactant aggregates. Charge densities as measured by EFM are used to estimate the depth of this electrostatically induced potential well, calculated to be on the order of hundreds of millielectronvolts, suggesting that surfactant charges heterogeneously covering SWCNTs provide traps for excitons potentially leading to their localization.

Low-temperature solution-processed high-capacitance AlOx dielectrics for low-voltage carbon-based transistors

Low-temperature processing of high-capacitance metal oxide-based dielectrics by solution-based methods and their application in developing low-voltage carbon-based transistors may enable next-generation low-cost, power-efficient, flexible and transparent electronics. In this work, a high-capacitance AlO x film was developed at a relatively low annealing temperature of ⁓200 °C from its spin-coated precursor solution. Its application in both low-voltage n- as well as p -channel field-effect transistors (FETs) was demonstrated, gaining feedback on microstructure and dielectric properties by using X-ray diffraction, X-ray photoelectron spectroscopy, atomic force microscopy, as well as impedance and current-voltage measurements. The operating voltage of both n -channel FETs based on a semiconducting polymer as well as p -channel FETs with polymer-sorted semiconducting (6,5) single-walled carbon nanotube (s-SWCNT) networks was found to be within 1.5 V range. This work demonstrates the viability of low-temperature AlO x dielectrics in low-voltage carbon-based electronics towards low-power distributed, portable and wearable applications. • Solution-processed AlO x is developed at a low temperature of 200 °C. • A 78 nm thick AlO x film has an areal capacitance of 105 nF cm −2 at 10 kHz. • Field-effect transistors are realized using both n -and p -type carbon-based semiconductors and AlO x as the dielectric. • The operating voltage of both types of transistors is within 1.5 V. • Our devices could be useful in low-power, portable, and wearable electronics.

Tailoring the density of carbon nanotube networks through chemical self-assembly by click reaction for reliable transistors

Semiconducting single-walled carbon nanotubes (sc-SWNTs) are attracting considerable interest for use as active layers in various electronic applications such as field-effect transistors (FETs) because of their extremely high intrinsic charge carrier mobility and solution processability at low costs. However, it is challenging to achieve a constant sc-SWNT density for ensuring commercial-level, uniform performance in FETs based on random-network SWNT films formed by solution processing. This paper reports a facile method for sorting sc-SWNT and precisely controlling the density of random-network sc-SWNT films by azide-functionalized polymer. The chemical self-assembly of SWNTs is performed between azide-functionalized polymer-wrapped sc-SWNTs and alkyne-based substrate via click reaction. A high-purity sc-SWNT ink is obtained by the conjugated polymer wrapping method using an azide-functionalized polyfluorene in methylcyclohexane. The sc-SWNTs are then chemically bound to a substrate with an alkyne adhesive layer through a Cu-catalyzed azide-alkyne cycloaddition reaction. FETs with dense and uniform SWNT films with a linear density of 30 (±2) tubes μm−1 exhibit markedly high hole mobility of up to 25.4 cm2 V−1 s−1 and excellent performance uniformity. Furthermore, the SWNT films anchored on the substrates are highly resistant to exogenous disruptions, such as sonication in organic solvents, leading the great potential for applications such as biosensors that require strong adhesive strength.

Light to heat conversion efficiency of single-walled carbon nanotubes

Semiconducting single-walled carbon nanotubes (s-SWCNTs) have the potential as light to heat efficiency, recently known as photothermal conversion efficiency , for photothermal therapeutic applications since they exhibit strong absorption in the near-infrared region (NIR). We report experimental studies of light to heat efficiency of two classes of s-SWCNTs, including double chiralities (DC) and many chiralities (MC) of s-SWCNTs. The was obtained by using the results from the experimental heating of s-SWCNTs with NIR light at 808 nm. Interestingly, the of MC s-SWCNTs was 1.88-fold higher than DC s-SWCNTs, which leads to a 19% decrease in the heating rate of DC compared to the heating rate of MC s-SWCNTs. This study demonstrates that chirality dependence is an essential metric in the heating rate of s-SWCNTs and provides a validated framework to compare the heating capabilities between DC and MC.

Room Temperature Lasing from Semiconducting Single-Walled Carbon Nanotubes.

Miniaturized near-infrared semiconductor lasers that are able to generate coherent light with low energy consumption have widespread applications in fields such as optical interconnects, neuromorphic computing, and deep-tissue optogenetics. With optical transitions at near-infrared wavelengths, diameter-tunable electronic structures, and superlative optoelectronic properties, semiconducting single-walled carbon nanotubes (SWCNTs) are promising candidates for nanolaser applications. However, despite significant efforts in this direction and recent progress toward enhancing spontaneous emission from SWCNTs through Purcell effects, SWCNT-based excitonic lasers have not yet been demonstrated. Leveraging an optimized cavity-emitter integration scheme enabled by a self-assembly process, here we couple SWCNT emission to the whispering gallery modes supported by polymer microspheres, resulting in room temperature excitonic lasing with an average lasing threshold of 4.5 kW/cm2. The high photostability of SWCNTs allows stable lasing for prolonged duration with minimal degradation. This experimental realization of excitonic lasing from SWCNTs, combined with their versatile electronic and optical properties that can be further controlled by chemical modification, offers far-reaching opportunities for tunable near-infrared nanolasers that are applicable for optical signal processing, in vivo biosensing, and optoelectronic devices.

Poly(ionic liquid) dielectric for high performing P- and N-type single walled carbon nanotube transistors

There is an increasing demand for low-cost and high-performance electronics which has stimulated a need for new high-performance dielectric materials. We have developed a facile synthesis of poly(2-(methacryloyloxy)ethyl trimethylammonium bis(trifluoromethylsulfonyl)azanide-ran-methyl methacrylate) (P(METATFSI-MMA)), a polymeric ionic liquid that can be used as a high-performance dielectric for semiconducting single walled carbon nanotube (SWCNTs) thin film transistors (TFTs). The P(METATFSI-MMA) polymer was synthesized at both 35 and 62 mol% of 2-(methacryloyloxy)ethyl trimethylammonium bis(trifluoromethylsulfonyl)azanide and produced p- and n-type devices that functioned under ambient conditions. These TFTs were then used to study the impact of electrochemical doping on the performance of SWCNT TFTs when switching from n-type, where an electrical double layer is formed, to p-type, where the TFSI− anions are free to interact with the SWCNTs. The TFTs operating in p-type had higher current on/off ratios and a larger transconductance than those operating in n-type, which is characteristic of electrochemically doped transistors. Furthermore, we tested the impact of operating frequency on device performance and discovered that decreasing the operating frequency of the TFTs resulted in a decreased hysteresis. The decrease in hysteresis was also observed to be more significant for the 35 mol% polymer.

Photochemical spin-state control of binding configuration for tailoring organic color center emission in carbon nanotubes

Incorporating fluorescent quantum defects in the sidewalls of semiconducting single-wall carbon nanotubes (SWCNTs) through chemical reaction is an emerging route to predictably modify nanotube electronic structures and develop advanced photonic functionality. Applications such as room-temperature single-photon emission and high-contrast bio-imaging have been advanced through aryl-functionalized SWCNTs, in which the binding configurations of the aryl group define the energies of the emitting states. However, the chemistry of binding with atomic precision at the single-bond level and tunable control over the binding configurations are yet to be achieved. Here, we explore recently reported photosynthetic protocol and find that it can control chemical binding configurations of quantum defects, which are often referred to as organic color centers, through the spin multiplicity of photoexcited intermediates. Specifically, photoexcited aromatics react with SWCNT sidewalls to undergo a singlet-state pathway in the presence of dissolved oxygen, leading to ortho binding configurations of the aryl group on the nanotube. In contrast, the oxygen-free photoreaction activates previously inaccessible para configurations through a triplet-state mechanism. These experimental results are corroborated by first principles simulations. Such spin-selective photochemistry diversifies SWCNT emission tunability by controlling the morphology of the emitting sites.

Superhydrophobic Paper-Based Microfluidic Field-Effect Transistor Biosensor Functionalized with Semiconducting Single-Walled Carbon Nanotube and DNAzyme for Hypocalcemia Diagnosis.

Hypocalcemia is caused by a sharp decline in blood calcium concentration after dairy cow calving, which can lead to various diseases or even death. It is necessary to develop an inexpensive, easy-to-operate, reliable sensor to diagnose hypocalcemia. The cellulose-paper-based microfluidic field-effect biosensor is promising for point-of-care, but it has poor mechanical strength and a short service life after exposure to an aqueous solution. Octadecyltrichlorosilane (OTS), as a popular organosilane derivative, can improve the hydrophobicity of cellulose paper to overcome the shortage of cellulose paper. In this work, OTS was used to produce the superhydrophobic cellulose paper that enhances the mechanical strength and short service life of MFB, and a microfluidic field-effect biosensor (MFB) with semiconducting single-walled carbon nanotubes (SWNTs) and DNAzyme was then developed for the Ca2+ determination. Pyrene carboxylic acid (PCA) attached to SWNTs through a non-covalent π-π stacking interaction provided a carboxyl group that can bond with an amino group of DNAzyme. Two DNAzymes with different sensitivities were designed by changing the sequence length and cleavage site, which were functionalized with SPFET/SWNTs-PCA to form Dual-MFB, decreasing the interference of impurities in cow blood. After optimizing the detecting parameters, Dual-MFB could determine the Ca2+ concentration in the range of 25 μM to 5 mM, with a detection limit of 10.7 μM. The proposed Dual-MFB was applied to measure Ca2+ concentration in cow blood, which provided a new method to diagnose hypocalcemia after dairy cow calving.

Electronic Properties and Band Gaps of Single-Wall Carbon Nanotubes Using <i>π</i> Orbitals Tight-Binding Model: A Comparative Study with <i>Ab Initio</i> Density Functional Theory

Semiconducting single-wall carbon nanotubes (SWCNTs) have already emerged as a promising candidate for molecular electronics and photovoltaic applications including solar cells. Any application of semiconducting SWCNTs is primarily related to proper information about its bandgap. In this work, the impact of the chirality indices and diameters of a series of armchair and zigzag SWCNTs on the electronic properties (band gap, electronic band structure and density of states (DOS)) are investigated using semi-empirical π orbitals tight-binding (TB) method. The results indicate that the electronic behaviour of the nanotubes changes according to chirality, the total number of electronic sub-bands gets increased when the chirality increases and Van Hove singularities (VHs) appear in its electronic DOS. We have found that for small diameter tubes (less than 0.8 nm), the calculated band gaps don’t agree with DFT calculations based on ab-initio (LDA and GGA) methods, which shows that the semi-empirical TB method including π orbitals only is not sufficient to give a reasonable description of small nanotubes. All Obtained results are in good agreement with previous studies. Semiconducting SWCNTs used in this study are particularly well-suited for the nanoelectronic devices and optoelectronic applications with their direct bandgap and optical transitions, while metallic SWCNTs are considered to be ideal candidates for variety of future nanoelectronic applications such as nanocircuit interconnects and power transmission cables.

Towards Monochiral Chemical Sensing with Near Infrared Fluorescent Carbon Nanotubes

Semiconducting single wall carbon nanotubes (SWCNTs) fluoresce in the near infrared (NIR) and the emission wavelength depends on their chirality (n,m). Interactions with the environment affect the fluorescence and can be tailored by functionalizing SWCNTs with biopolymers such as DNA, which is the basis for fluorescent biosensors. So far, such biosensors were mainly assembled from mixtures of SWCNT chiralities with large spectral overlap, which affects sensitivity as well as selectivity and prevents multiplexed sensing. The main challenge to gain chirality pure sensors has been to combine approaches to isolate specific SWCNTs and generic (bio)functionalization approaches. Here, we report several approaches to assemble chirality pure SWCNT-based NIR biosensors, with a major focus on aqueous two-phase extraction (ATPE) assisted purification and novel surface exchange protocols. We study the impact of SWCNT chirality/handedness on chemical sensing and highlight possible applications for detection of neurotransmitters, ROS, bacterial motives of plant metabolites. Finally, we use multiple monochiral/single-color SWCNTs as combined ratiometric/multiplexed nanosensors for NIR detection and imaging.