Breaking the trade-off between thermal and electrical conductivities in the thermoelectric material of an artificially tilted multilayer

Breaking the trade-off between thermoelectric (TE) parameters has long been demanded in order to highly enhance its performance. Here, we report the 'trade-off-free' interdependence between thermal conductivity (κ) and resistivity (ρ) in a TE/metal tilted multilayer and significant enhancement of TE power generation based on the off-diagonal thermoelectric (ODTE) effect, which generates transverse electrical current in response to vertical thermal current. ρ and κ can be simultaneously decreased by setting charge flow along more-electrically conductive layer and thermal flow across less-thermally conductive perpendicular direction by decreasing the tilting angle. Moreover, introducing porosity in the metal layer enables to decrease in κ without changing ρ, because the macroscopic ρ and κ of the tilted multilayer is respectively governed by the properties of the TE material and the metal with large dissimilarity. The obtained results reveal new strategies for developing trade-off-free TE materials, which will stimulate practical use of TE conversion for waste-heat recovery.