Glassy Thermal Transport Triggers Ultra-High Thermoelectric Performance in GeTe.

The consequences of broken long-range atomic arrangement in glasses or amorphous solids are reflected in the temperature dependence of lattice thermal conductivity (κ). However, the appearance of glassy ultralow κ in a crystalline solid with high electrical transport like metal is unusual but can have a remarkable impact on the thermoelectric performance of a material. Here, an ultra-high thermoelectric performance is demonstrated with a maximum figure of merit, zT ≈ 2.

Coupling-Induced Dynamic Off-Centering of Cu Drives High Thermoelectric Performance in TlCuS.

Seeking new and efficient thermoelectric materials requires a detailed comprehension of chemical bonding and structure in solids at microscopic levels, which dictates their intriguing physical and chemical properties. Herein, we investigate the influence of local structural distortion on the thermoelectric properties of TlCuS, a layered metal sulfide featuring edge-shared Cu-S tetrahedra within CuS layers. While powder X-ray diffraction suggests average crystallographic symmetry with no distortion in CuS tetrahedra, the synchrotron X-ray pair distribution function experiment exposes concealed local symmetry breaking, with dynamic off-centering distortions of the CuS tetrahedra.