Figure 1. Concept of trade-off-free interrelation between κ and ρ using the ODTE effect.

The behaviours of thermal conductivity (κ), resistivity (ρ) and ρ⁻¹κ⁻¹ of a thermoelectric (TE) material controlled by (a) carrier-density and (b) PGEC concept. (c) Schematic illustration of the off-diagonal TE effect in a tilted artificial multilayer of a TE material and metal. The large arrows show the macroscopic thermal (red) and charge (orange) currents. Also shown are two mechanisms for improving ρ⁻¹κ⁻¹ in the multilayer: (d) simultaneous decrease in κ and ρ by changing the tilt angle and (e) independent decrease in κ and constant ρ by increasing the porosity of the metal.