Thermoelectric performance of ternary Cu-based chalcogenide Cu2TiTe3.

In this work, we report the ternary Cu-based chalcogenide, Cu₂TiTe₃, as a promising thermoelectric material in middle-temperature range. The bonding interaction between Te p and Ti d states is observed in the Ti–Te octahedron, which drives the side bands up converging with Γ band, yielding a high valence band degeneracy of 5. A high electronic quality factor of 2.2 μW cm⁻¹ K⁻² and a decent power factor of 7.5 μW cm⁻¹ K⁻² at 300 K are achieved for Cu₂TiTe₃. Likewise, Cu₂TiTe₃ demonstrates low lattice thermal conductivity throughout the measured temperature range, which is attributed to the low frequency vibration related to the global motion of Ti–Te–Cu clusters. Finally, a maximum figure-of-merit of 0.38 was obtained for Cu₂TiTe₃ at 600 K. [ABSTRACT FROM AUTHOR]