RESUMEN

Electro-conductive films with excellent flexibility and thermal behavior have great potential in the fields of wearable electronics, artificial muscle, and soft robotics. Herein, we report a super-elastic and electro-conductive composite film with a sandwich structure. The composite film was constructed by spraying Polyvinyl alcohol (PVA) polymers onto a buckled conductive carbon nanotube-polydimethylsiloxane (CNTs-PDMS) composite film. In this system, the PVA and PDMS provide water sensing and stretchability, while the coiled CNT film offers sufficient conductivity. Notably, the composite film possesses high stretchability (205%), exceptional compression sensing ability, humility sensing ability, and remarkable electrical stability under various deformations. The produced CNT composite film exhibited deformation (bending/twisting) and high electro-heating performance (108 °C) at a low driving voltage of 2 V. The developed CNT composite film, together with its exceptional sensing and electrothermal performance, provides the material with promising prospects for practical applications in wearable electronics.

RESUMEN

With the rapid development in information, communication, energy, medical care, and other fields, the demand for light, strong, flexible, and stable materials continues to grow. Carbon nanotube (CNT) films possess outstanding properties, such as flexibility, good tensile properties, low density, and high electrical conductivity, making them promising materials for a wide range of applications. This paper reports an effective strategy that combines stretching treatment, laser etching, and electron beam deposition to fabricate an iron-deposited CNT film, which can serve as a counter electrode (CE) of quantum-dot-sensitized solar cells. The study also investigates the influences of processing parameters, such as stretching ratio and iron-depositing thickness on the film's stacking structure, electrical conductivity, and catalytic activity. Under optimized stretching ratios and depositing thicknesses, the catalytic activity of the reacted deposited layer and the high electrical conductivity of the flexible film basis can be fully utilized, allowing the photoelectric conversion efficiency (PCE) of the solar cells to reach approximately 4.58%. Additionally, the CE exhibits flexibility, light transmission, and good stability, with its primary properties remaining above 97% after nearly 50 days. Thus, this research provides innovative material options and development strategies for the development of electrode materials.

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Flexible electronics toward high integration, miniaturization, and multifunctionality, leading to a dramatic increase in power density. However, the low thermal conductivity of flexible substrates impedes efficient heat dissipation and device performance improvement. In this work, we propose a template-assisted chemical conversion strategy for obtaining boron nitride nanotube (BNNT) films with high thermal conductivity and great flexibility. Aligned carbon nanotube (CNT) films have been adopted as templates; a low-temperature chemical conversion followed by a high-temperature annealing has been carried out to produce a highly ordered BNNT film. Benefiting from the high orientation order, the BNNT film exhibits an exceptional thermal conductivity of 45.5 W m-1 K-1 and presents excellent heat dissipation capability, much superior to the commonly used polyimide film. Furthermore, the BNNT film demonstrated excellent flexibility and high insulation resistance. The test of integration with film resistors demonstrated its potential as a thermally conductive substrate for electronics cooling. This work provides a solution for the effective thermal management of flexible electronics.

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A polarized light source covering a wide wavelength range is required in applications across diverse fields, including optical communication, photonics, spectroscopy, and imaging. For practical applications, high degrees of polarization and thermal performance are needed to ensure the stability of the radiation intensity and low energy consumption. Here, we achieved efficient emission of highly polarized and broadband thermal radiation from a suspended aligned carbon nanotube film. The anisotropic nature of the film, combined with the suspension, led to a high degree of linear polarization (∼0.9) and great thermal performance. Furthermore, we performed time-resolved measurements of thermal emission from the film, revealing a fast time response of approximately a few microseconds. We also obtained visible light emission from the device and analyzed the film's mechanical breakdown behavior to improve the emission intensity. Finally, we demonstrated that suspended devices with a constriction geometry can enhance the heating performance. These results show that carbon nanotube film-based devices, as electrically driven thermal emitters of polarized radiation, can play an important role for future development in optoelectronics and spectroscopy.

RESUMEN

Field electron emission characteristics of the carbon nanotube (CNT) film emitters were investigated according to densification conditions such as nitric acid, acetic acid, and salicylic acid. The emission performance of the CNT film emitters was strongly affected by the densification conditions. Salicylic acid exhibits the best field electron emission properties of the CNT film emitters, followed by nitric acid and acetic acid. The efficient densification of the CNT film emitter by salicylic acid is caused by the role of polarity and p orbitals, nitric acid by hydrogen ions, and acetic acid by weak polarity. After the densification with salicylic acid, the turn-on field of the CNT film emitter decreases from 1.94 Vµm-1to 1.86 Vµm-1, the threshold field decreases from 3.41 Vµm-1to 2.95 Vµm-1, the emission current significantly increases from 20.92 mA to 43.98 mA, and the degradation rate from the long-term emission stability decreases from 49.9% to 21%. The improved emission characteristics are attributed to the increased emission sites at the CNT film and the increased electrical conductivity of the CNT film. The densification is a useful way to enhance the field electron emission properties of CNT film emitters.

RESUMEN

Spectroscopic analysis with polarized light has been widely used to investigate molecular structure and material behavior. A broadband polarized light source that can be switched on and off at a high speed is indispensable for reading faint signals, but such a source has not been developed. Here, using aligned carbon nanotube (CNT) films, we have developed broadband thermal emitters of polarized infrared radiation with switching speeds of ≲20 MHz. We found that the switching speed depends on whether the electrical current is parallel or perpendicular to the CNT alignment direction with a significantly higher speed achieved in the parallel case. Together with detailed theoretical simulations, our experimental results demonstrate that the contact thermal conductance to the substrate and the conductance to the electrodes are important factors that determine the switching speed. These emitters can lead to advanced spectroscopic analysis techniques with polarized radiation.

RESUMEN

An integrated solution providing a bi-stable antenna with reconfigurable performance and light-responsive behavior is presented in this paper for the first time. The proposed antenna includes a radiation layer with conductivity, which is integrated onto the bi-stable substrate. First, the effect of the radiation layer material and substrate layer parameters on antenna performance was studied. The experiment showed that an antenna with CNTF has a wider impedance bandwidth than one with CSP, namely 10.37% versus 3.29%, respectively. The resonance frequency increases gradually with the increase in fiber laying density and fiber linear density. Second, the influence of state change of the substrate layer on the antenna radiation pattern was studied. The measured results showed that the maximum radiation angle and gain of states I and II are at 90°, 1.21 dB and 225°, 1.53 dB, respectively. The gain non-circularities of the antenna at states I and II are 4.48 dB and 8.35 dB, respectively, which shows that the antenna has good omnidirectional radiation performance in state I. The display of the array antenna, which shows that the array antenna has good omnidirectional radiation performance in state A, with gain non-circularities of 4.20 dB, proves the feasibility of this bi-stable substrate in reconfigurable antennas. Finally, the antenna deforms from state I to state II when the illumination stimulus reaches 22 s, showing good light-responsive behavior. Moreover, the bi-stable composite antenna has the characteristics of small size, light weight, high flexibility, and excellent integration.

RESUMEN

Carbon nanotube (CNT) is an ideal candidate material for shortwave infrared (SWIR) detectors due to its large band gap tunability, strong infrared light absorption, and high mobility. Furthermore, the photodetectors based on CNT can be prepared on any substrate using a low-temperature process, which is conducive to three-dimensional (3D) integration. However, owing to the absorption limitation (<2%) of a single-layer network CNT film with low density, the photodetectors of CNT film show low photocurrent responsivity and detectivity. In this paper, we optimize the thickness of the high-purity semiconducting network CNT films to increase the photocurrent responsivity of the photodetectors. When the thickness of network CNT film is about 5 nm, the responsivity of the zero-bias voltage can reach 32 mA/W at 1800 nm wavelength. Then, using stacked CNT films and contact electrode design, the photodetectors exhibit a maximum responsivity of 120 mA/W at 1800 nm wavelength. The photodetectors with stacked CNT films and local n-type channel doping demonstrated a wide response spectral range of 1200-2100 nm, a peak detectivity of 3.94 × 109 Jones at room temperature, and a linear dynamic range over 118 dB. Moreover, the peak detectivity is over 2.27 × 1011 Jones when the temperature is 180 K. Our work demonstrates the potential of the CNT film for future SWIR imaging at a low cost.

RESUMEN

Fabricating electronic and optoelectronic devices by transferring pre-deposited metal electrodes has attracted considerable attention, owing to the improved device performance. However, the pre-deposited metal electrode typically involves complex fabrication procedures. Here, we introduce our facile electrode fabrication process which is free of lithography, lift-off, and reactive ion etching by directly press-transferring a single-walled carbon nanotube (SWCNT) film. We fabricated Schottky diodes for photodetector applications using dry-transferred SWCNT films as the transparent electrode to increase light absorption in photoactive MoS2 channels. The MoS2 flake vertically stacked with an SWCNT electrode can exhibit excellent photodetection performance with a responsivity of ∼2.01 × 103 A/W and a detectivity of ∼3.2 × 1012 Jones. Additionally, we carried out temperature-dependent current-voltage measurement and Fowler-Nordheim (FN) plot analysis to explore the dominant charge transport mechanism. The enhanced photodetection in the vertical configuration is found to be attributed to the FN tunneling and internal photoemission of charge carriers excited from indium tin oxide across the MoS2 layer. Our study provides a novel concept of using a photoactive MoS2 layer as a tunneling layer itself with a dry-transferred transparent SWCNT electrode for high-performance and energy-efficient optoelectronic devices.

RESUMEN

Ultrabroadband photodetectors (PDs) working in the frequency range from the UV to THz regions of the spectrum play a crucial role in integrated multifunction photoelectric detection. Even so, a shortage of high-performance PDs has seriously restricted the overall development of this field. The present work demonstrates a high-performance, ultrabroadband PD with a composite nanostructure comprising a suspended carbon nanotube (CNT) film on which titanium and palladium are deposited. The application of titanium and palladium to the CNT film in this device provides n-doping and p-doping, respectively, and the deposited metal nanoparticles also ensure enhanced thermal localization. This device exhibits short response time, high responsivity, large linear dynamic range, and small noise equivalent power over the ultrabroadband spectrum based on a strong photothermoelectric effect. Numerical simulation results also confirm the effective doping and enhanced thermal localization in this PD resulting from the deposited metals. A theoretical analysis shows that the thermal conductivity of the composite film is no longer independent of the temperature over a wide temperature range. This work provides a simple but novel strategy for the design of high-performance ultrabroadband PDs.

RESUMEN

The functional microporous layer, acting as a mass-transfer control medium with a rational structure and surface morphology as well as high electrical conductivity, significantly affects the performance of micro-direct methanol fuel cells (µDMFCs). Bioinspired by the architecture and multi-functional properties of mangrove roots, this study develops a simple and versatile strategy based on magnetron sputtering and chemical vapor deposition to fabricate a mangrove root-inspired carbon nanotube film (MR-CNTF) as the functional interface in µDMFCs. It has features such as ultralightweight, high porosity, and good electrical conductivity. During the synthesis process, an apex-growth model of CNTF is identified. The results indicate that the MR-CNTF used as a cathodic microporous layer can remarkably facilitate the oxygen transport and water management. Because of its multi-functional structure and excellent material characteristics, the passive µDMFC displays a peak power density of 14.9 mW cm-2 at 68 mA cm-2. This value is 88.6% higher than the highest power density of the one based on a carbon nanotube array (7.9 mW cm-2) and 45% higher than that of the conventional carbon black (10.7 mW cm-2). We believe that this novel material with its multi-functional structure illuminates a promising application for fuel cells and other energy storage and conversion devices.

RESUMEN

Polymer membranes typically possess a broad pore-size distribution that leads to much lower selectivity in ion separation when compared to membranes made of crystalline porous materials; however, they are highly desirable because of their easy processability and low cost. Herein, we demonstrate the fabrication of ion-sieving membranes based on a polycarbazole-type conjugated microporous polymer using an easy to scale-up electropolymerization strategy. The membranes exhibited high uniform sub-nanometer pores and a precisely tunable membrane thickness, yielding a high ion-sieving performance with a sub-1 Å size precision. Both experimental results and molecular simulations suggested that the impressive ion-sieving performance of the CMP membranes originates from their uniform and narrow pore-size distribution.

RESUMEN

This paper fabricates a carbon nanotube (CNT ) film-reinforced mesophase pitch-based carbon (CNTF/MPC) nanocomposite by using a hot-pressing carbonization method. During the carbonization, the stacked aromatic layers tended to rearrange into amorphous carbon, and subsequently generated crystalline carbon in the matrix. The continuous entangled CNT networks were efficiently densified by the carbon matrix though optimized external pressure to obtain the high-performance nanocomposites. The CNTF/MPC@1300 displayed a stable electrical conductivity up to 841 S/cm at RT-150 °C. Its thermal conductivity in the thickness direction was 1.89 W/m∙K, an order of magnitude higher than that of CNT film. Moreover, CNTF/MPC@1300 showed a mass retention of 99.3% at 1000 °C. Its tensile strength was 2.6 times the CNT film and the tensile modulus was two orders of magnitude higher. Though the CNTF/MPC nanocomposites exhibited brittle tensile failure mode, they resisted cyclic bending without damage. The results demonstrate that the CNTF/MPC nanocomposite has potential application in multi-functional temperature resistance aerospace structures.

RESUMEN

We investigated the microstructures of carbon nanotube (CNT) films and the effect of CNT length on their mechanical performance. 230 µm-, 300 µm-, and 360 µm- long CNTs were grown and used to fabricate CNT films by a winding process. Opposite from the length effect on CNT fibers, it has been found that the mechanical properties of the CNT films decrease with increasing CNT length. Without fiber twisting, short CNTs tend to bundle together tightly by themselves in the film structure, resulting in an enhanced packing density; meanwhile, they also provide a high degree of CNT alignment, which prominently contributes to high mechanical properties of the CNT films. When CNTs are long, they tend to be bent and entangled, which significantly reduce their packing density, impairing the film mechanical behaviors severely. It has also been unveiled that the determinant effect of the CNT alignment on the film mechanical properties is more significant than that of the film packing density. These findings provide guidance on the optimal CNT length when attempting to fabricate high-performance macroscopic CNT assemblies.

RESUMEN

The charge storage mechanism and capacity of supercapacitors completely depend on the electrochemical and mechanical properties of electrode materials. Herein, continuously reinforced carbon nanotube film (CNTF), as the flexible support layer and the conductive skeleton, was prepared via the floating catalytic chemical vapor deposition (FCCVD) method. Furthermore, a series of novel flexible self-supporting CNTF/polyaniline (PANI) nanocomposite electrode materials were prepared by cyclic voltammetry electrochemical polymerization (CVEP), with aniline and mixed-acid-treated CNTF film. By controlling the different polymerization cycles, it was found that the growth model, morphology, apparent color, and loading amount of the PANI on the CNTF surface were different. The CNTF/PANI-15C composite electrode, prepared by 15 cycles of electrochemical polymerization, has a unique surface, with a "sea-cucumber-like" 3D nanoprotrusion structure and microporous channels formed via the stacking of the PANI nanowires. A CNTF/PANI-15C flexible electrode exhibited the highest specific capacitance, 903.6 F/g, and the highest energy density, 45.2 Wh/kg, at the current density of 1 A/g and the voltage window of 0 to 0.6 V. It could maintain 73.9% of the initial value at a high current density of 10 A/g. The excellent electrochemical cycle and structural stabilities were confirmed on the condition of the higher capacitance retention of 95.1% after 2000 cycles of galvanostatic charge/discharge, and on the almost unchanged electrochemical performances after 500 cycles of bending. The tensile strength of the composite electrode was 124.5 MPa, and the elongation at break was 18.9%.

RESUMEN

Carbon nanotubes (CNTs) and boron nitride nanotubes (BNNTs) are one-dimensional materials with high thermal conductivity and similar crystal structures. Additionally, BNNTs feature higher thermal stability in air than CNTs. In this work, a single-walled carbon nanotube (SWCNT) film was used as a template to synthesize a BNNT coating by the chemical vapor deposition (CVD) method to form a coaxial heterostructure. Then, a contact-free steady-state infrared (IR) method was adopted to measure the in-plane sheet thermal conductance of the as-synthesized film. The heterostructured SWCNT-BNNT film demonstrates an enhanced sheet thermal conductance compared with the bare SWCNT film. The increase in sheet thermal conductance shows a reverse relationship with SWCNT film transparency. An enhancement of over 80% (from ∼3.6 to ∼6.4 µW·K-1·sq-1) is attained when the BNNT coating is applied to an SWCNT film with a transparency of 87%. This increase is achieved by BNNTs serving as an additional thermal conducting path. The relationship between the thermal conductance increase and transparency of the SWCNT film is studied by a structured modeling of the SWCNT film. We also discuss the effect of annealing on the thermal conductance of SWCNTs before BNNT growth. Along with the preservation of high electrical conductance, the enhanced thermal conductance of the heterostructured SWCNT-BNNT films makes them a promising building block for thermal and optoelectronic applications.

RESUMEN

The shuttle of the long-chain lithium polysulfides (LiPSs) is the main obstacle to the practical application of lithium-sulfur batteries. Herein, a poly(butyl acrylate/1-ethyl-3-vinylimidazole bis[(trifluoromethyl)sulfonyl]imide)-based quasi-solid-state copolymer electrolyte poly(ethylene glycol) diacrylate (PEGDA-P(BA-co-[EVIm]TFSI) QPE-IL) was prepared for lithium-sulfur batteries. The butyl acrylate component with abundant ester groups ensures the strong chemical capture for LiPSs. What is more, the introduction of ionic liquid ([EVIm]TFSI) can greatly improve the ionic conductivity and lithium-ion migration rate. More importantly, the dynamic-reversible adsorption of LiPSs was realized by chemical adsorption of ester-rich groups and electrostatic repulsion of free-moving negatively charged ions. As a result, the lithium-sulfur battery assembled by a reduced graphene oxide/carbon nanotube film@sulfur (rGOCTF@S) self-supporting cathode and QPE-IL displayed a high initial discharge capacity of 1179 mA h g-1, good cycling stability (72% capacity retention after 200 cycles at 0.5 C), and superior rate performance.

RESUMEN

Along with ultralow-energy delay products and symmetric complementary polarities, carbon nanotube field-effect transistors (CNT FETs) are expected to be promising building blocks for energy-efficient computing technology. However, the work frequencies of the existing CNT-based complementary metal-oxide-semiconductor (CMOS) integrated circuits (ICs) are far below the requirement (850 MHz) in state-of-art wireless communication applications. In this work, we fabricated deep submicron CMOS FETs with considerably improved performance of n-type CNT FETs and hence significantly promoted the work frequency of CNT CMOS ICs to 1.98 GHz. Based on these high-speed and sensitive voltage-controlled oscillators, we then presented a wireless sensor interface circuit with working frequency up to 1.5 GHz spectrum. As a preliminary demonstration, an energy-efficient wireless temperature sensing interface system was realized combining a 150 mAh flexible Li-ion battery and a flexible antenna (center frequency of 915 MHz). In general, the CMOS-logic high-speed CNT ICs showed outstanding energy efficiency and thus may potentially advance the application of CNT-based electronics.

RESUMEN

A superaligned carbon nanotube (SACNT) film can act as an ideal gate electrode in vacuum electronics due to its low secondary electron emission, high electron transparency, ultrasmall thickness, highly uniform electric field, high melting point, and high mechanical strength. We used a SACNT film as the gate electrode in a thermionic emission electron tube and field emission display prototype. The SACNT film gate in a thermionic emission electron tube shows a larger amplification factor. A triode tube with the SACNT film gate is used in an audio amplification circuit. The SACNT film gate electrode in field emission devices shows better field uniformity. The field emission display prototype is demonstrated to dynamically display Chinese characters.

RESUMEN

Interfacing nanoelectronic devices with cell membranes can enable multiplexed detection of fundamental biological processes (such as signal transduction, electrophysiology, and import/export control) even down to the single ion channel level, which can lead to a variety of applications in pharmacology and clinical diagnosis. Therefore, it is necessary to understand and control the chemical and electrical interface between the device and the lipid bilayer membrane. Here, we develop a simple bottom-up approach to assemble tethered bilayer lipid membranes (tBLMs) on silicon wafers and glass slides, using a covalent tether attachment chemistry based on silane functionalization, followed by step-by-step stacking of two other functional molecular building blocks (oligo-poly(ethylene glycol) (PEG) and lipid). A standard vesicle fusion process was used to complete the bilayer formation. The monolayer synthetic scheme includes three well-established chemical reactions: self-assembly, epoxy-amine reaction, and EDC/NHS cross-linking reaction. All three reactions are facile and simple and can be easily implemented in many research labs, on the basis of common, commercially available precursors using mild reaction conditions. The oligo-PEG acts as the hydrophilic spacer, a key role in the formation of a homogeneous bilayer membrane. To explore the broad applicability of this approach, we have further demonstrated the formation of tBLMs on three common classes of (nano)electronic biosensor devices: indium-tin oxide-coated glass, silicon nanoribbon devices, and high-density single-walled carbon nanotubes (SWNT) networks on glass. More importantly, we incorporated alemethicin into tBLMs and realized the real-time recording of single ion channel activity with high sensitivity and high temporal resolution using the tBLMs/SWNT network transistor hybrid platform. This approach can provide a covalently bonded lipid coating on the oxide layer of nanoelectronic devices, which will enable a variety of applications in the emerging field of nanoelectronic interfaces to electrophysiology.

Asunto(s)

Técnicas Biosensibles , Membrana Dobles de Lípidos , Nanotubos de Carbono , Silanos , Silicio