High-Performance n-Type Carbon Nanotubes Doped by Oxidation of Neighboring SbTe for a Flexible Thermoelectric Generator.

Flexible thermoelectric devices can be potentially used for flexible cooling and energy harvesting from various heat sources such as the human body. However, the development of flexible thermoelectric materials with excellent thermoelectric performance is still very challenging. In this study, a simple solution process is proposed for the preparation of flexible inorganic/carbon nanotube hybrid films with record power factors among those of the reported flexible n-type thermoelectric materials. The hybrid films fabricated by bar-coating a carbon nanotube-dispersed SbTe solution exhibit n-type power factors of up to 2440 ± 267 μV m K at room temperature. The dissolved SbTe recrystallizes on the carbon nanotube surfaces and form hybrid solids. The ultrahigh power factor may be originated from the effective n-doping of carbon nanotubes by the oxidation of neighboring SbTe. Using the thermoelectric hybrid film, a multilayer stacked thermoelectric generator is fabricated. The flexible device with a thermal contact area of 3.8 cm exhibits an output power of up to 11.3 μW at a vertical Δ of 7.5 K. This study paves the way for the realization of flexible thermoelectric devices with various device geometries.