title: Development of n-type cobaltocene-encapsulated carbon nanotubes with remarkable thermoelectric property.
abstract: Direct conversion from heat to electricity is one of the important technologies for a sustainable society since large quantities of energy are wasted as heat. We report the development of a single-walled carbon nanotube (SWNT)-based high conversion efficiency, air-stable and flexible thermoelectric material. We prepared cobaltocene-encapsulated SWNTs (denoted CoCp2@SWNTs) and revealed that the material showed a negative-type (n-type) semiconducting behaviour (Seebeck coefficient: -41.8 μV K(-1) at 320 K). The CoCp2@SWNT film was found to show a high electrical conductivity (43,200 S m(-1) at 320 K) and large power factor (75.4 μW m(-1) K(-2)) and the performance was remarkably stable under atmospheric conditions over a wide range of temperatures. The thermoelectric figure of merit (ZT) value of the CoCp2@SWNT film (0.157 at 320 K) was highest among the reported n-type organic thermoelectric materials due to the large power factor and low thermal conductivity (0.15 W m(-1) K(-1)). These characteristics of the n-type CoCp2@SWNTs allowed us to fabricate a p-n type thermoelectric device by combination with an empty SWNT-based p-type film. The fabricated device exhibited a highly efficient power generation close to the calculated values even without any air-protective coating due to the high stability of the SWNT-based materials under atmospheric conditions.
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka Nishi-ku, Fukuoka 819-0395, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Fukumaru
authors.affiliation: 1] Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka Nishi-ku, Fukuoka 819-0395, Japan [2] International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University 744 Motooka Nishi-ku, Fukuoka 819-0395, Japan.
authors.forename: Tsuyohiko
authors.initials: T
authors.lastname: Fujigaya
authors.affiliation: 1] Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka Nishi-ku, Fukuoka 819-0395, Japan [2] International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University 744 Motooka Nishi-ku, Fukuoka 819-0395, Japan [3] JST-CREST, 5 Sanbancho, Chiyoda-ku, Tokyo, 102-0075, Japan.
authors.forename: Naotoshi
authors.initials: N
authors.lastname: Nakashima