Cu-Embedded SnSe₂ with a High Figure of Merit at Ecofriendly Temperature

There are many studies concentrated on high-temperature performance of SnSe₂, but few studies were conducted on low-temperature properties of embedded SnSe₂. In this work, a series of SnCu Se₂ (x = 0, 0.01, 0.02, and 0.05) layered structures have been successfully synthesized by a melt quenching, mechanical milling process, and spark plasma sintering (SPS) method. Meanwhile, the thermal and electrical transport properties of all synthesized samples are measured. These results suggest that the embedding of Cu into SnSe₂ results in a high carrier concentration (10¹⁹/cm³). In addition, the enhancement of defect and interfacial phonon scattering caused by Cu embedding as well as the weak van der Waals force between layers makes a low thermal conductivity (0.81 W/mK) for the SnCu_0.01Se₂ at 300 K. Moreover, the maximum ZT is acquired up to 0.75 for the SnCu_0.01Se₂ sample at 300 K, which is about 2 orders of magnitude higher than the pristine sample (0.009). These features indicate that Cu-embedded SnSe₂ can be a promising thermoelectric material at gentle temperature.