High-purity semiconducting single-walled carbon nanotubes (s-SWCNTs) have attracted increasing attention as sensing materials for the detection of chemical warfare agents (CWAs). Their excellent semiconducting properties and extremely large surface areas give them very high sensitivity for detecting chemicals in the vapor phase. However, their practical sensing applications are often limited by poor selectivity due to the nonspecific adsorption of various environmental gases. To address this challenge, we covalently functionalized s-SWCNTs with tetrafluorophenol (TFP), a strong hydrogen-bond donor (pK a = 5.53), via a diazonium reaction using 4-aminotetrafluorophenol (ATFP). The resultant TFP-functionalized s-SWCNTs (TFP-SWCNTs) were characterized by absorption, Raman, and X-ray photoelectron spectroscopy (XPS) and exhibited significantly enhanced performance for sensing dimethyl methylphosphonate (DMMP, a simulant of CWAs). The TFP-SWCNTs had TFP contents ([TFP]/[C]) ranging from 0.012 to 0.315%. Samples with [TFP]/[C] values of 0.045% and 0.093% showed markedly improved DMMP sensing performance, reducing the limit of detection (LOD) from 50 ppb in prior work to 0.01 ppb in nitrogen and 0.9 ppb in dry air. Notably, even in 15% relative humidity (RH) air, the sensors maintained excellent sensitivity, with a 4.5 ppb LOD, promising for field-deployed applications. Moreover, we observed a 10-20-fold increase in sensor response in humid air as DMMP concentration increased from 35.5 to 1204 ppb, compared to a 3-4-fold increase under a similar DMMP concentration change in dry conditions. Computer simulations indicate that this effect is due to the formation of an H2O bridge between DMMP and TFP, which enhances charge transfer (0.060e from DMMP to TFP) compared to direct DMMP-TFP binding (0.049e). In addition, TFP-SWCNTs exhibited strong DMMP selectivity against interfering volatile organic compounds (VOCs) including methanol, acetone, toluene, and N,N '-dimethylformamide (DMF). All these behaviors highlight a strong potential of TFP-SWCNTs for real-world sensing applications.

ABSTRACT Semiconducting single‐walled carbon nanotubes (SWCNTs) are attractive for near‐infrared (NIR) sensing but suffer from weak photocurrent due to large exciton binding energies. Here, we pair chirality‐enriched (10,9)‐ SWCNT as the electron acceptor with a sustainable, furfural‐derived π‐conjugated polymer ( PFEB ) as the electron donor to fabricate lateral, resistor‐type p‐n heterojunction NIR photodetectors to facilitate exciton dissociation. Post‐deposition thermal cleavage of PFEB ’s carbamate side chains yields PFNB , which tightens polymer–nanotube contact and switches the dominant response of the sensors from ∼800 to ∼1000 nm. The optimized PFNB /(10,9)‐enriched SWCNT device on SiO 2 substrates achieves EQE = 19.7%, R = 0.159 A W −1 , and D * = 2.66 × 10 8 Jones at 1000 nm and 1.0 V, while an all‐printed device on a polyimide substrate reaches EQE = 6.47%, R = 0.0522 A W −1 , and D * = 7.90 × 10 7 Jones. Photoluminescence‐excitation quenching (∼78%) and redshifts/broadening in (10,9)‐enriched SWCNT optical bands evidence strong interfacial coupling and interfacial charge transfer. The devices require neither transparent electrodes nor complex stacks, and they are fabricated via ultrasonic micro‐printing using picoliter ink volumes. This work demonstrates a scalable route to high‐performance, low‐power, and environmentally friendly NIR sensing.

Physiological media ( e.g. , sweat, saliva, serum) contain several chemical and biological biomarkers which can be diagnostic of certain diseases or overall health condition. Because of the media’s high ionic content (~100 mM), an electrical double layer (EDL) is established with a very short Debye length, λ D < 1 nm. Beyond λ D , it is generally accepted that an electric charge is screened and cannot be sensed at the electrode. Typical strategies for electronic sensing in high ionic strength media include grafting a permeable polymer such as polyethylene glycol (PEG) to the sensor’s surface [1], structuring confined volumes [2], and interrogating using impedance spectroscopy [3]. Short receptors like aptamers can also be used, as they bind with the target at a distance on the order of the Debye length. [4] I will present the results of aptasensors for cortisol detection in 1X PBS buffer. The aptasensors use gold nanoparticle (AuNP)-decorated carbon nanotubes for electrical signal passthrough in physiological media. This architecture employs the efficient metal chelation by bipyridine units (BPy) in the conjugated polymer’s backbone wrapping semiconducting carbon nanotubes (sc-SWCNTs), poly(9,9-di- n -dodecylfluorenyl-2,7-diyl- alt -2,2′-bipyridine-5,5′) (PFBPy-5,5’), providing tight chemical anchoring. [5] The 5,5’-linkage improves PFBPy’s wrapping stability against metal complexation over the more common 6,6’-linkage. AuNPs were grown on sc-SWCNTs@PFBPy-5,5’ using electrochemical reduction of Au ions. A cortisol aptasensor was prepared by attaching thiol-terminated cortisol aptamers to the sc-SWCNT@PFBPy-5,5’+AuNP system, and integrated into an electrolyte-gated field-effect transistor. The biosensor, operating in 1X PBS buffer, provided excellent response to cortisol in the range of 1 – 1000 nM, which corresponds to cortisol’s physiological concentration range in sweat. References [1] Gao, N. et al. General Strategy for Biodetection in High Ionic Strength Solutions Using Transistor-Based Nanoelectronic Sensors. Nano Lett. 15 2143–2148 (2015) [2] Shoorideh, K. & Chui, C. O. On the origin of enhanced sensitivity in nanoscale FET-based biosensors. Proc. Nat. Acad. Sci. 111 5111–5116 (2014) [3] Kulkarni, G. S. & Zhong, Z. Detection beyond the Debye Screening Length in a High-Frequency Nanoelectronic Biosensor. Nano Lett. 12 719–723 (2012) [4] Stuber, A. & Nakatsuka, N. Aptamer Renaissance for Neurochemical Biosensing. ACS Nano 18 2552–2563 (2024) [5] Ding, J. et al. Silver Nanoparticles Anchored on Single-Walled Carbon Nanotubes via a Conjugated Polymer for Enhanced Sensing Applications. ACS Omega 8 14219–14232 (2023)

Photodynamic therapy (PDT) is a minimally invasive treatment that utilizes photosensitizing agents activated by specific light wavelengths to produce reactive oxygen species, leading to the destruction of targeted cells. However, the efficacy of these photosensitizers is compromised by their limited solubility and stability. Although nanocarriers for photosensitizers such as boron nitride nanotubes (BNNTs) have been investigated for their biocompatibility and stability, their tendency to form large aggregates in aqueous solutions poses a challenge. In this study, a hydrogel based on dialdehyde starch and chitosan with dynamic Schiff-type bonds is presented as a carrier for hybrid polythiophene/boron nitride nanotube-based photosensitizers to target and destroy cancer cells. The BNNTs were non-covalently functionalized with polythiophenes (PT-BNNTs), having different functional groups on the side chains. The obtained water-soluble PT-BNNT hybrids exhibit a red-shift in their absorption spectra, aligning with the optimal therapeutic window (600 nm to 900 nm) for PDT. The hydrogels with PT-BNNTs showed rapid gelation (<1 min) and remarkable self-healing behavior within 20 min, as confirmed by rheological measurements, owing to the imine bonds. In vitro assays with DU-145 cancer cells showed that hydrogels containing PT-BNNTs significantly increased reactive oxygen species production, by up to 4.6 times compared to hydrogels without PT-BNNTs. Furthermore, cell viability decreased by 70 % after irradiation compared to controls with non-irradiated hydrogels. These results indicate that self-healing chitosan/dialdehyde starch hydrogels with polythiophene-functionalized BNNTs have great potential as photosensitizer carriers for photodynamic cancer therapy.

Metal nanocrystals (NCs) have been synthesized and used as highly efficient electrocatalysts for the electrocatalytic CO2 reduction reaction (eCO(2)RR) in recent years. Electrocatalysts with various metal sizes and morphologies have achieved remarkable improvement in the CO2 reduction. However, the syntheses are typically energy-demanding and the catalysts exhibit low mass activity. Ultrasmall metal NCs synthesized by a one-step process at room temperature and an ambient environment stand out because of cost-effectiveness in materials and energy. Here, we report a facile synthesis to produce 1 nm gold nanocrystals in ambient conditions, which was realized by an in situ reduction of AuCl3 on a semiconducting single-walled carbon nanotube (sc-SWCNT) surface. In addition, the bipyridine (BPy) units in tube-wrapped polymers function as chelating sites for anchoring Au3+ and AuNCs. The ultrasmall size of AuNCs was achieved by fast AuCl3 diffusion and the anchoring function of BPy units. A slow diffusion or absence of BPy units resulted in AuNCs in larger sizes. The NC density was controlled by AuCl3 feed amounts by varying the Au-to-BPy molar ratios. Density functional theory was applied to simulate the Au-BPy coordination. The fabricated nanocomposites exhibited a high Faradaic CO selectivity up to 86% at 25 mA/cm(2) and a high mass activity up to 5.61 A/mg (Au) at 100 mA/cm(2), which is the highest value reported so far in AuNC electrocatalysts for CO2 reduction.

Achieving high selectivity among chemically similar analytes remains a critical challenge for organic thin-film transistor (OTFT)-based gas sensors. We report a molecular imprinting strategy that imparts both size- and interaction-selective sensing by covalently incorporating ethanol molecules into acid-cleavable acetal side chains of the semiconducting polymer TAT-2. Subsequent HCl vapor treatment cleaves these side chains, generating subnanometer pores and free aldehyde groups in the resulting polymer TFT-2, as confirmed by FTIR analysis. These structural features facilitate selective diffusion and hydrogen-bonding interactions with small alcohols. TAT-2 and TFT-2 exhibit HOMO energy levels of -5.29 and -5.37 eV, respectively, rendering them stable p-type semiconductors with hole mobilities of ∼10-4-10-3 cm2 V-1 s-1 in OTFTs under nitrogen and ambient air. While TAT-2 OTFTs responded nonselectively to ethanol and other VOCs, TFT-2 devices demonstrated high sensitivities to ethanol (1.11 × 10-4 ppm-1) and methanol (0.61 × 10-4 ppm-1), but much lower responses to isopropanol (0.11 × 10-4 ppm-1), acetone (0.0057 × 10-4 ppm-1), and negligible responses to larger or nonpolar VOCs. Unlike TAT-2 devices, which showed current decreases, TFT-2 devices exhibited current increases upon methanol and ethanol exposure, likely due to pore filling that passivates charge-trapping sites and enhances charge transport. This side-chain engineering approach establishes a new paradigm for molecular imprinting in semiconducting polymers, enabling facile device fabrication with functional microstructures for selective analyte recognition.

Conjugated polymer-sorted semiconducting single-walled carbon nanotubes (sc-SWCNTs) are excellent materials for electronic biosensors due to their high electrical conductivity and sensitivity and can be integrated into electrolyte-gated field-effect transistor (EGFET) sensors. Operation of electronic biosensors in bodily fluids is challenging because of the short Debye length (lambda D ) in high ionic strength media. The receptor attached to the sc-SWCNT is a crucial component of the biosensor, and sensor performance depends on efficient signal transduction between the receptor and the sc-SWCNT. In this work, we grew Au nanoparticles (NPs) on sc-SWCNTs wrapped with a copolymer of fluorene and 2,2'-bipyridine (BPy), poly(9,9-di-n-dodecylfluorenyl-2,7-diyl-alt-2,2 '-bipyridine-5,5 ') (PFBPy-5,5 '). AuNPs were anchored to the BPy ligands in the polymer backbone, realizing an efficient electrical connection between the AuNPs and the sc-SWCNTs. Cortisol sensors were prepared by coupling a thiol-terminated cortisol aptamer to the AuNPs and integrating the Aptamer/AuNP/sc-SWCNT@PFBPy-5,5 ' complex into an EGFET. The sensor exhibited a concentration-dependent increase in source-drain current upon increasing cortisol concentration from 1 to 1000 nM. A control sensor was prepared using sc-SWCNTs wrapped with a fluorene homopolymer, poly(9,9-dodecylfluorene) (PFDD), which does not have a ligand that AuNPs can anchor. The control Aptamer/AuNP/sc-SWCNT@PFDD sensor showed only a weak concentration-dependent response. A further control was prepared using sc-SWCNTs@PFDD with the aptamer covalently attached to the nanotube's sidewall. The Covalent-Aptamer/sc-SWCNT@PFDD control sensor exhibited a concentration-dependent response, albeit to a lesser extent than the Aptamer/AuNP/sc-SWCNT@PFBPy-5,5 ' system. The results indicate that tight-anchoring of AuNPs in the Aptamer/AuNP/sc-SWCNT@PFBPy-5,5 ' system provides a crucial contribution to the proposed sensing mechanism: (1) upon cortisol recognition, the aptamer undergoes a structure-switch where the negatively charged backbone is brought within or near the Debye length at the AuNP surface, altering the interfacial capacitance and electrostatically gating the AuNP and (2) efficient signal transfer between the AuNPs and sc-SWCNTs@PFBPy-5,5 '.

The demand for a high-throughput and noncontact monitoring system to guarantee the payload of nucleic acid in liposomes is rapidly increasing for raising efficiency in gene therapeutics. Herein, inspired by electroreceptors of elasmobranch fishes, a dynamic liposome sensing (DLs) platform is developed by implementing the electret layer (CYTOP)-coated single-walled carbon nanotube-based thin film transistor (eSWCNT-TFT) which can monitor differences of the net-charge on deoxyribonucleic acid (DNA)-loaded liposomes. The SWCNT-TFTs are roll-to-roll (R2R) printed on plastic film and then, simply laminated by the droplet microfluidic chip to optimize the aqueous droplet lengths by controlling a ratio of injecting speed between oil to aqueous solution. The buffer solution, DNA-free liposomes, and DNA-loaded liposomes respectively induced different electrostatic potentials on eSWCNT-TFTs without direct contact with the electret layer, thereby shifting the threshold voltage (Vth). The DLs platform's integrated wireless communication module can monitor DNA-loaded liposome droplets with encapsulation efficiency of up to 87.3 ± 3.2% with a sensitivity of 18.61 nA ppm-1 per single droplet at a flow rate of 1 µL min-1. It can be scaled up by adding more microfluidic droplet channels on eSWCNT-TFT arrays, making it especially useful for in-situ checks of messenger ribonucleic acid (mRNA)-based vaccines just before bottling.

[This corrects the article DOI: 10.1021/acsanm.5c00783.].

To date, colloidal quantum dots (CQDs) with absorption in the short-wave infrared region (SWIR, 1-2.6 mu m) typically consist of hazardous cadmium, lead, or mercury chalcogenides, which limit commercial acceptance. Environmentally friendly alternatives are therefore required to ensure minimal damage to ecosystems during fabrication, use, and disposal. A promising hazardous-element-free SWIR absorbing nanomaterial candidate is tin chalcogenide. We have developed tin telluride (SnTe) CQDs, with a size ranging from similar to 17 to 26 nm and corresponding absorption peak from similar to 2.3 to 2.5 mu m, indicative of size-dependent quantum confinement. Air-stable tin salts (tin chloride or tin acetate) were employed instead of the typical air-sensitive bis(bis(trimethylsilyl)amino tin(II). The synthesis was systematically investigated by optimizing the ligand type (1-dodecanethiol was used to replace oleic acid to prevent oxidation), injection method, growth temperature, reaction time, and feed molar ratio between tin and tellurium precursors. To improve stability in air, a ZnTe shell was successfully synthesized via cation exchange reaction at 70 degrees C with zinc acetate. The SnTe/ZnTe core-shell nanocrystals were fully characterized, revealing the formation of a protective ZnTe shell with a thickness of two to three monolayers, resulting in long-term stability in air (up to 1 month). These air-stable CQDs may offer a low-toxicity alternative nanomaterial for low-cost solution-processable fabrication of SWIR optoelectronics.

Low-cost photodetectors with sensitivity in the second near-infrared window (NIR-II, 1000–1700 nm) are highly demanded. Recently, we made the first demonstration of an Ag 2 Se colloidal quantum dots (QDs) photodiode with sensitivity up to 1200 nm. By employing secondary phosphine to elevate the precursor reactivity, the Ag 2 Se QDs with a distinct excitonic absorption peak was achieved. These nanocrystals were deposited from solution into a mesoporous TiO 2 scaffold to increase the light absorption and charge separation and reduce the exciton diffusion length. By incorporating a suitable hole-transporting layer between the active layer and Ag anode, the resulting devices showed a responsivity of 4.17 mA/W at 1200 nm. 1 Also, Ag 2 Te QDs are excellent for advancing the detection wavelength. Their synthesis with desired particle sizes, narrow size distribution and high photoluminescence quantum yield (PL QY) is challenging. We systematically investigate critical parameters affecting the synthesis in an organic phase. It shows that high Ag/Te feed ratio leads to smaller size and higher PL QY; under 4:1 Ag/Te feed molar ratio, addition of secondary phosphine leads to narrower size distribution and excellent colloidal stability; under 6:1 Ag/Te feed molar ratio, excess 1-dodecanethiol as a strong ligand slows the nucleation and results in fewer nuclei, leading to a broad size distribution and poor optical properties; additional n-trioctyl phosphine as a weak ligand provides better colloidal stability; and another weak ligand n-tributylphosphine improves Ag 2 Te QD colloidal stability, focuses size distribution, and enhances PL QY. After optimization relatively large Ag 2 Te QDs with distinct excitonic absorption peaks (~1050 – 1450 nm) and PL emission peak 1.3 – 1.7 µm (QY up to 6.2%) were obtained. NIR-II photodetection has been demonstrated with a responsivity of ~1.5 mA/W at 1400 nm. 2 More recently, we have been developing Sn-based chalcogenide QDs and obtained preliminary photodetection results. These results demonstrate that Ag and Sn chalcogenide QDs offer a low-toxicity route for low-cost fabrication of NIR-II photodetection. Reference: [1] Graddage N, Ouyang J, Lu J, Chu TY, Zhang Y, Li Z, Wu X, Malenfant PRL, Tao Y. Near-Infrared-II Photodetectors Based on Silver Selenide Quantum Dots on Mesoporous TiO 2 Scaffolds. ACS Applied Nano Materials 2020 , 3: 12209–12217. [2] Ouyang J, Graddage N, Lu J, Zhong Y, Chu TY, Zhang Y, Wu X, Kodra O, Li Z, Tao Y, Ding J. Ag 2 Te Colloidal Quantum Dots for Near-Infrared-II Photodetectors. ACS Applied Nano Materials 2021 , 4: 13587–13601. Keywords: Environmentally Friendly; Near Infrared; Quantum Dots; Photodetection.

The study has developed two hemi-isoindigo (HID)-based polymers for printed flexible resistor-type nitrogen oxide (NO2) sensors: poly[2-ethylhexyl 3-((3 '",4 '-bis(dodecyloxy)-3,4-dimethoxy-[2,2 ':5 ',2 '"-terthiophen]-5-yl)methylene)-2-oxoindoline-1-carboxylate] (P1) and poly[2-ethylhexyl 2-oxo-3-((3,3 '",4,4 '-tetrakis(dodecyloxy)-[2,2 ':5 ',2 '"-terthiophen]-5-yl)methylene)indoline-1-carboxylate] (P2). These polymers feature thermally removable carbamate side chains on the HID units, providing solubility and creating molecular cavities after thermal annealing. These cavities enhance NO2 diffusion, and the liberated unsubstituted amide C(O)NH groups readily form robust double hydrogen bonds (DHB), as demonstrated by computer simulations. Furthermore, both polymers possess elevated highest occupied molecular orbital (HOMO) energy levels of -4.74 and -4.77 eV, making them highly susceptible to p-doping by NO2. Gas sensors fabricated from P1 and P2 films, anneal under optimized conditions to partially remove carbamate side chains, exhibit remarkable sensitivities of +1400% ppm(-1) and +3844% ppm(-1), and low detection limit (LOD) values of 514 ppb and 38.9 ppb toward NO2, respectively. These sensors also demonstrate excellent selectivity for NO2 over other gases.

The control of the performance of single-walled carbon nanotube (SWCNT) random network-based transistors is of critical importance for their applications in electronic devices, such as complementary metal oxide semiconducting (CMOS)-based logics. In ambient conditions, SWCNTs are heavily p-doped by the H2O/O2 redox couple, and most doping processes have to counteract this effect, which usually leads to broadened hysteresis and poor stability. In this work, we coated an SWCNT network with various common polymers and compared their thin-film transistors’ (TFTs’) performance in a nitrogen-filled glove box. It was found that all polymer coatings will decrease the hysteresis of these transistors due to the partial removal of charge trapping sites and also provide the stable control of the doping level of the SWCNT network. Counter-intuitively, polymers with electron-withdrawing functional groups lead to a dramatically enhanced n-branch in their transfer curve. Specifically, SWCNT TFTs with poly (vinylidene fluoride) coating show an n-type mobility up to 61 cm2/Vs, with a decent on/off ratio and small hysteresis. The inverters constructed by connecting two ambipolar TFTs demonstrate high gain but with certain voltage loss. P-type or n-type doping from polymer coating layers could suppress unnecessary n- or p-branches, shift the threshold voltage and optimize the performance of these inverters to realize rail-to-rail switching. Similar devices also demonstrate interesting antiambipolar performance with tunable on and off voltage when tested in a different configuration.

Bulk heterojunction (BHJ) organic solar cells based on p-type polymers and n-type fullerene derivatives have attracted increasing attention due to their promising potential for providing low–cost solar electricity. In this paper, we will introduce our recent work on the development of new fullerene derivatives. Through Rh complex catalyzed coupling reactions and cycloaddition reactions, we attached several organic functional groups to the fullerene skeleton. It was found that the organic substituents had little impact on the fullerene energy levels. Instead, the organic substituents have huge impact on the other physical properties of the resulting fullerene derivatives, such as solubility, crystallinity, and electron mobility. We designed and synthesized a novel series of alkoxy substituted indene derivatives as solubilizing groups for fullerenes. Preliminary experimental results demonstrated that these 5 alkoxyindene modified C70 derivatives are superior to widely used PC71BM when blended with poly[N-heptadecanyl-2,7 carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'- benzothiadiazole)] (PCDTBT) in BHJ solar cells. The device series resistance decreased from 10 cm2 for the PC71BM based device to 4 cm2 for the 5-methoxyindene-C70 monoadduct based device. As a result, the device fill factor increased from 0.60 to 0.69, and the overall EQE-calibrated power conversion efficiency was enhanced from 5.6% to 6.2%.

Single-walled carbon nanotubes (SWCNTs) are candidate matrices for loading metal nanoparticles (NPs) for sensor and catalytic applications owing to their high electron conductivity and mechanical strength, larger surface area, excellent chemical stability, and ease of surface modification. The performance of the formed NP/SWCNT composites is dependent on the NP size, the physical and chemical interactions between the components, and the charge transfer capabilities. Anchoring metal complexes onto the surface of SWCNTs through noncovalent interactions is a viable strategy for achieving high-level metal dispersion and high charge transfer capacities between metal NPs and SWCNTs. However, traditional metal complexes have small molecular sizes, and their noncovalent interactions with SWCNTs are limited to provide excellent sensing and catalytic capability with restricted efficiency and durability. Here, we selected poly(9,9-di-n-dodecylfluorenyl-2,7-diyl-alt-2,2'-bipyridine-5,5') (PFBPy) to increase the noncovalent interactions between silver nanoparticles (AgNPs) and SWCNTs. A silver triflate (Ag-OTf) solution was added into a PFBPy-wrapped SWCNT solution to form Ag-PFBPy complexes on the nanotube surface, after which Ag+ was photoreduced to AgNPs to form a Ag-PFBPy/SWCNT composite in the solution. In various feeding molar ratios of Ag-OTf over the BPy unit (0.4-50), the size of the formed AgNPs may be well-controlled at sub-nm levels to provide them with an energy level comparable to that of the SWCNTs. Additionally, the 2,2'-bipyridine (BPy) unit of the polymer provided a coordinating interaction with Ag+ and the formed AgNPs as well. The 5,5'-linage of BPy with the fluorene unit in PFBPy ensured a straight main chain structure to retain strong π-π interactions with nanotubes before and after Ag+ chelation. All of these factors confirmed a tight contact between the formed AgNPs and SWCNTs, promoting the charge transfer between them and enhancing the sensing capabilities with a 5-fold increase in humidity sensing sensitivity.

Single-walled carbon nanotube (SWCNT) network based devices show application potentials due to their extraordinary electric and optical properties, and the device performance is largely determined by the network morphology and tube-tube junction interactions. In this work, five SWCNT samples with narrow bandgap distributions covering a wide diameter range of 0.7-1.6 nm were purified by the conjugated polymer extraction (CPE) process. Both chirality distribution and semiconducting purity of these samples were systematically characterized by optical methods. Uniform high density network based thin film transistors (TFTs) were fabricated, and their performance can be related to tube bandgap/diameter and defects density or tube length. The diameter-dependent tube-tube junction resistance, the most important parameter for nanowire network devices, was extracted using a network predictive model. It was found that junction resistance inversely scales with tube diameter and is about 2 orders of magnitude higher than tube intrinsic resistance. The impacts of network morphology, tube diameter, and length on their network TFT performance were further discussed. We hope these results can provide some guideline to address various application challenges for SWCNT network based devices.

Polymer characteristics influence the chiral selectiv-ity and yield in the enrichment of (7,6) from Signis SG76 in toluene by various fluorene homopolymers and copolymers. Fluorene homopolymers such as poly(9,9-di-n-dodecylfluorene) (PFDD) and copolymers with anthracene such as poly[(9,9-dihexylfluorenyl-2,7-diyl)-co-(9,10-anthracene)] (PFH-A) result in high (7,6) selectivities of up to 67 and 72%, respectively. The selectivity is calculated by optical absorption using a known extinction coefficient and also evaluated by Raman scattering and photoluminescence excitation. In contrast, poly[(9,9-dioctyl-2,7-divinylenefluorenylene)-alt-co-(9,10-anthracene)] (PFO=A), with a double-bond spacer, results in (9,5) dominant extractions with the purity of (9,5) up to 80% after ultracentrifugation, which is believed to be the first report on the successful enrichment of (9,5) by conjugated polymers. The chiral selectivity is also greatly impacted by the length of alkyl side chain of fluorene homopolymers: hexyl group has low selectivity, while octyl, dodecyl, and tetradecyl (PFTD) groups show high selectivity toward (7,6), and the octadecyl group is prone to include bigger tubes. Interestingly, a chiral selection transition from (7,6) to (8,6) occurred using PFTD after a few enrichment cycles. The chiral purity of (8,6) was greatly improved from 50 to 86% after slow filtration. Polymer molecular weight (MW, here PFDD) also plays a role in the selectivity and yield. Low MW leads to a low yield, and high MW leads to a low selectivity, with the optimal range (Mn) being ca. 20-35 kDa when the polydisperse index is ca. 2-3. Molecular dynamics simulation confirms that different lengths of side chain of polyfluorene have different wrapping stabilities toward specific chirality, where PFTD shows greater stability toward (8,6) than (7,6).

Carbon nanotubes (CNTs) are a rapidly maturing emerging technology for next-generation energy-efficient digital Very-Large-Scale-Integrated (VLSI) systems. However, a major remaining challenge facing CNT field-effect transistors (CNFETs) are metallic CNTs, causing incorrect logic functionality and increased leakage power. As no CNT synthesis technique demonstrates a reliable path toward manufacturing 99.99% semiconducting CNTs (s-CNT; required purity for VLSI systems), significant work focuses on solution-based sorting of CNTs (selectively removing metallic CNTs post-synthesis). Yet, there lacks both well-controlled comparisons carefully optimizing key processing parameters simultaneously (CNT synthesis sources, polymer additive used for selective sorting, etc.), as well as statistically significant electrical transistor characterization sample sizes to form concrete conclusions. Here, >90 000 CNFETs (totaling >90 million CNTs) are fabricated and characterized to demonstrate the following key advances: 1) systematic exploration of the impact of different combinations of CNT synthesis sources and polymer additives on the electrical performance of transistors (analyzing on-current, off-current, on off ratio, and threshold voltage) to find the best combination, 2) how the optimization and choice of the CNT source can be decoupled from that of the polymer, and 3) an optimal CNT solution that achieves >99.99% s-CNT purity using electrical measurements, meeting the requirement for VLSI systems.

SWCNT-based thin-film transistors (TFTs) typically display unipolar p-type electrical characteristics in ambient condition due to the O2/H2O redox couple. However, complementary circuits that combine both p and n channels are preferred due to lower power requirements. Typical approaches with small molecule or polymeric dopants often yield ambipolar devices, or unstable n-type devices while concomitantly suppressing the on-current and mobility. Herein, we demonstrate a charge carrier control strategy using aqueous-based polymeric coatings that enable n-type devices with comparable performance to p-type devices. Specifically, we used a polyvinyl alcohol (PVA) coating layer containing a minority fraction of polyethyleneimine (PEI) (0.06–1.1 % w/w) to effectively switch the transfer characteristics from p-type to n-type, while maintaining decent electrical characteristics. Moreover, we demonstrate the ability to fine-tune the n branch threshold voltage via the annealing temperature. A similar strategy provides a balanced p branch on-current by incorporating PVA as a minor component (0.1-6 % w/w) into a polyacrylic acid (PAA) matrix. Through effective n-type conversion and p-type balancing, we demonstrate a simple SWCNT-based inverter. Considering the low-cost, environmentally friendly compositions and aqueous processability, this approach is attractive for large scale complementary printable circuits.

Ag2Te colloidal quantum dots (QDs) are an excellent nanomaterial for applications in the second near-infrared window (NIR-II, 1000-1700 nm). However, synthesis with narrow size distribution and high photoluminescence quantum yield (PL QY) is challenging. In this study, we systematically investigate critical synthesis parameters affecting an organic phase process. We show that high Ag/Te feed ratio leads to smaller size and higher PL QY; under 4:1 Ag/Te feed molar ratio, addition of secondary phosphine leads to narrower size distribution and excellent colloidal stability; under 6:1 Ag/Te feed molar ratio, excess 1-dodecanethiol as a strong ligand slows the nucleation and results in fewer nuclei, leading to a broad size distribution and poor optical properties; additional trioctylphosphine as a weak ligand provides better colloidal stability; and another weak ligand tributylphosphine improves QD colloidal stability, focuses size distribution, and enhances PL QY. A noninjection method maintains narrow size distribution in upscaling syntheses. After optimization, relatively large Ag2Te QDs with distinct excitonic absorption peaks (similar to 1050-1450 nm) and PL emission peak 1.3-1.7 mu m (QY up to 6.2%) were obtained. NIR-II photodetection has been demonstrated with a responsivity of similar to 1.5 mA/W at 1400 nm.