Low thermal conductivity in GeTe-based thermoelectric materials with additional activated carbon

In order to improve the performance of thermoelectric materials, nanoinclusions are often used to enhance phonon scattering. In this study, activated carbon, which is porous and thus has a large surface area, was incorporated in GeTe-based materials to cause increased boundary phonon scattering. Carbon dispersed in grain boundaries resulted in improved thermal properties without significant deterioration in electrical properties. Due to the extrinsic addition of activated carbon, the lattice thermal conductivity decreased by 13.8% on average. A maximum dimensionless figure of merit of 1.66 was achieved at 723K for the Ge0.9Sb0.1Te composition with additional activated carbon.