Research overview
  • Buckypaper: Thin films made of carbon nanotubes (CNTs) are called buckypaper (BP), which is expected to be applied to various electronic devices. Usually, BP is made by chemical vapor deposition method. Our research group has successfully used vacuum filtration method to make low-cost BP.

  • Thermoelectricity: Thermoelectric power generation is one of the expected new renewable energies in the future. However, the power generation capacity of thermoelectric devices is still low. Thermoelectric conversion that can convert direct heat to electric power is attracting attention as a power generation technology without carbon dioxide emission and without moving parts such as turbine. Functional thermoelectric devices can generate electricity anywhere there is a heat source. Conversely, they can be used as a cooling device without the use of pump or fluid by supplying current. Maximizing the effectiveness of the thermoelectric module, which restricts their applications in both electricity generation and cooling device, are of principle importance. Superior thermoelectric devices must have high thermoelectric figure index and low cost. The efficiency of thermoelectric devices is related to the thermoelectric figure of merit, ZT, defined as S2σT/K, where S denotes the Seebeck coefficient, σ is the electrical conductivity, k is the thermal conductivity, and T is the absolute temperature. Good thermoelectric materials must have a high Seebeck coefficient for enhanced thermoelectricity, low electrical resistivity to minimize Joule heating, and low thermal conductivity to sustain large temperature gradient. Currently, many thermoelectric materials are inorganic semiconductors. However, some thermoelectric semiconductor materials are not practical because they are highly toxic and expensive. Therefore, our group focuses on organic materials, which are expected to promote thermoelectric devices. Among various organic materials, we are interested in using carbon nanotubes because it has many desirable characteristics from the viewpoint of thermoelectric conversion.
Current research topics
1. Buckypaper: (1) Fabricating highly flexible BP by using various types of binders; (2) Discovering new application areas for BP; (3) Finding new methods to improve BP conductivity and strength.

Figure 1. Photo image of the fabricated buckypaper

2. Thermoelectricity: (1) Fabricating low-cost but high-performance thermoelectric devices; (2) Discorvering new method to improve thermoelectric properties of multiwalled carbon nanotube; (3) Designing novel themoelectric divices with practical characteristics such as low cost, flexiblity, light weight.

Figure 2. The experimental result of a developed thermoelectricity device