Thermoelectric materials have the ability to generate
electricity when a temperature difference is applied to them.
Conversely, they can also generate a temperature gradient when
current is applied to them. Therefore, these materials are expected
to find use as power generators of electronic devices and coolers
or heaters of temperature control devices. To develop these
applications, a thermoelectric material showing high thermoelectric
voltage (called thermopower S), even on applying low thermal
energy, is required. However, conventional thermoelectric materials
exhibit high conversion efficiency at high temperatures, whereas
there are only a few candidates that show high conversion
performance at below room temperature.