Fabrication of Aligned-Carbon-Nanotube-Composite Paper with High and Anisotropic Conductivity

Abstract

A functional carbon-nanotube (CNT)-composite paper is described in which the CNTs are aligned. This “aligned-CNT composite paper” is a flexible composite material that has CNT functionality (e.g., electrical conductivity) despite being a paper. An advanced fabrication method was developed to overcome the problem of previous CNT-composite papers, that is, reduced conductivity due to random CNT alignment. Aligning the CNTs by using an alternating current (AC) field was hypothesized to increase the electrical conductivity and give the paper an anisotropic characteristic. Experimental results showed that a nonionic surfactant was not suitable as a CNT dispersant for fabricating aligned-CNT composite paper and that catechin with its six-membered rings and hydrophilic groups was suitable. Observation by scanning electron microscopy of samples prepared using catechin showed that the CNTs were aligned in the direction of the AC field on the paper fibers. Measurement of the electric conductivity showed that the surface resistance was different between the direction of the aligned CNTs (high conductivity) and that of verticality (low). The conductivity of the aligned-CNT-composite paper samples was higher than that of nonaligned samples. This unique and functional paper, which has high and anisotropic conductivity, is applicable to a conductive material to control the direction of current.

Aligned SWNT Films from Low-Yield Stress Gels and Their Transparent Electrode Performance

“…Simulations have shown that partial alignment can indeed reduce the resistivity compared to a randomly oriented film. , However, this has not been demonstrated experimentally because of the lack of a controllable method that can achieve tunable alignment while maintaining a high tube density. There have been many studies attempting to align CNTs. ,− These studies have used methods such as utilizing chemical vapor deposition (CVD), − embedding CNTs in liquid crystals, − spin-coating, and using concentration dependent self-alignment. − However, none of these methods are ideal. Some are too costly and/or have a low throughput, whereas others are not scalable or have poor density control.…”

Unique Dye-Sensitized Solar Cell Using Carbon Nanotube Composite Papers with Gel Electrolyte

“…Figure 4 shows the chemical structural formula of purple sweet potato dye. It is widely known that molecules containing benzene rings and hydroxyl groups, such as catechin [17,18], have the ability to disperse CNTs in water through π-π stacking interaction. As shown in Figure 4, this molecule also has several benzene ring structures, which we considered to have the ability to disperse CNTs, like catechins.…”

“Paper Dye-Sensitized Solar Cell” Based on Carbon-Nanotube-Composite Papers

“…Here, the dye was expected to be the dispersant for CNTs. It is known that the molecules that have benzene rings and hydroxy groups, such as catechin [27,28], have the ability to disperse CNTs in water. The benzene rings of molecules are drawn and adsorbed on the surface of CNTs by the synergy effects of π-π stacking interaction.…”