Transparent Single-walled Carbon Nanotube Films Research Articles

Highly efficient doping of carbon nanotube films with chloroauric acid by dip-coating

Single-walled carbon nanotube (SWCNT) based transparent and conductive films (TCFs) are one of the most prospective materials for novel flexible and stretchable electronic devices. Development of reproducible and scalable doping procedure is the key step towards the widespread implementation of SWCNT TCFs. Here, we thoroughly investigate a dip-coating technique for SWCNT doping as a promising approach for the practical manufacturing of SWCNT films with high performance. We examine the effect of dip-coating parameters on optical and electrical properties of the films using HAuCl4 solution in isopropyl alcohol (IPA) and in situ investigate doping effects. This method appeared to easily fine-tune the optoelectronic parameters of SWCNT films and achieve a record sheet resistance value of 36 Ohm/sq. at the 90% transmittance in the middle of visible spectral range by increasing a work function value from 4.8 (for pristine SWCNTs) to 6.0 eV. The proposed approach allows efficient, uniform, and reproducible fabrication of highly conductive and transparent SWCNT films and opens an avenue for precise tailoring of SWCNT Fermi level for optoelectronic devices.

Highly conductive and transparent single-walled carbon nanotube thin films from ethanol by floating catalyst chemical vapor deposition.

Single-walled carbon nanotube (SWCNT) films have great potential to replace indium tin oxide films for applications in transparent and conductive electronics. Here we report a high yield production of SWCNT transparent conducting films (TCFs) by the floating catalyst chemical vapor deposition method using ethanol as the carbon source. To the best of our knowledge, this is the first report regarding SWCNT TCFs using ethanol as the carbon source. The fabricated uniform SWCNT TCFs exhibit a competitive sheet resistance of 95 Ω sq-1 at 90% transmittance after doping with AuCl3. The SWCNT TCFs possess high quality and the mean length of SWCNT bundles is approximately 27.4 μm. Furthermore, the concentration of semiconducting SWCNTs is 75-77%. Additionally, the chirality maps obtained from electron diffraction analysis demonstrate that our SWCNTs are biased towards the armchair type.

Fabrication of conductive and transparent single-walled carbon nanotube films with PEDOT

Poly(3,4-ethylenedioxythiophene) is electropolymerized on a single-walled carbon nanotube film to reduce sheet resistance without causing loss in transparency.

Self-passivation of transparent single-walled carbon nanotube films on plastic substrates by microwave-induced rapid nanowelding

We developed a straightforward method for enhancing the environmental stability of transparent single-walled carbon nanotube (SWCNT) network films on plastic substrates using a rapid microwave heating to produce SWCNT film–substrate nanowelding without any chemicals. The selective heating of SWCNTs induced by microwave irradiation leads to embedding the SWCNTs in the substrate, even within 10 s, without distortion of the substrate. The SWCNTs-embedded surface of the substrate played the role of a self-passivation layer that protected the SWCNTs from water molecules. The sheet resistance values of the nanowelded films had not increased more than 10%.

Graphene oxide as a multi-functional p-dopant of transparent single-walled carbon nanotube films for optoelectronic devices

Modulation of electronic structures and surface properties of transparent carbon nanotube films is a challenging issue for their application in optoelectronic devices. Here, we report, for the first time, that graphene oxide (GO) nanosheets play the role of a p-doping agent and surface energy modifier of single-walled carbon nanotube (SWCNT)-based transparent conducting electrodes (TCEs). The deposition of highly oxidized, small-sized (i.e., diameter of less than 500 nm) GO nanosheets onto a SWCNT network film reduces the sheet resistance of the pristine film to 60% of its original value by p-doping. The modified TCEs exhibit an outstanding optoelectronic feature of high conductivity with high transparency. Moreover, the wettability of the electrode surface was also noticeably increased, which is advantageous for the solution-based processing of organic electronics. Furthermore, the organic photovoltaic (OPV) cells with the GO-doped SWCNT anodes on flexible substrates were successfully demonstrated. In stark contrast to a power conversion efficiency of 0.44% for pristine SWCNT anodes, GO-doped SWCNT anodes show a drastically enhanced power conversion efficiency of 2.7%.

Solution Processing of Highly Conductive and Transparent Single-Walled Carbon Nanotube Films: Surfactant-Free Dispersions and Non-Acidic Dopants

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Ultra Smooth, Large Area, High Uniformity, Conductive Transparent Single-Walled Carbon Nanotube Films for Photovoltaics Produced by Ultrasonic Spraying

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Micropatterning of Transparent Single-Walled Carbon Nanotube Films by Capacitively Coupled Plasma System

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Electrochemical patterning of gold nanoparticles on transparent single-walled carbon nanotube films

We report a simple, low cost, electrochemical deposition method to pattern gold nanoparticles on flexible, transparent, single-walled carbon nanotube (SWCNT) films, and demonstrate the application of the gold-patterned SWCNT films as surface-enhanced Raman spectroscopy substrates and biosensing electrodes for non-enzymatic glucose detection.

Directly Synthesized Strong, Highly Conducting, Transparent Single-Walled Carbon Nanotube Films

We report the direct synthesis of strong, highly conducting, and transparent single-walled carbon nanotube (SWNT) films. Systematically, tests reveal that the directly synthesized films have superior electrical and mechanical properties compared with the films made from a solution-based filtration process: the electrical conductivity is over 2000 S/cm and the strength can reach 360 MPa. These values are both enhanced by more than 1 order. We attribute these intriguing properties to the good and long interbundle connections. Moreover, by the help of an extrapolated Weibull theory, we verify the feasibility of reducing the interbundle slip by utilizing the long-range intertube friction and estimate the ultimate strength of macroscale SWNTs without binding agent.

Electrowetting devices with transparent single-walled carbon nanotube electrodes

Microfluidic devices based on the electrowetting principle, more specifically electrowetting on dielectric, were fabricated using transparent single-walled carbon nanotube films as electrodes. The films were spray coated on glass and polyethylene terephalate substrates. The transmittance and sheet resistance remain unchanged after patterning the films using typical photolithography and plasma etching. Operation of water droplets over the patterned nanotube electrodes was demonstrated, and the performance was found to be comparable to that over the usual metal electrodes. The requirement of transparent electrodes is estimated for displays based on electrowetting machanism, and nanotube films indicate promise for such a type of devices.

Charge dynamics in transparent single-walled carbon nanotube films from optical transmission measurements

We report the transmission over a wide frequency range (far infrared - visible) of pristine and hole-doped, free-standing carbon nanotube films at temperatures between 50 K and 300 K. Optical constants are estimated by Kramers-Kronig analysis of transmittance. We see evidence in the far infrared for a gap below 10 meV. Hole doping causes a shift of spectral weight from the first interband transition into the far infrared. Temperature dependence in both the doped and undoped samples is restricted to the far-infrared region.