High Thermoelectric Performance of a Novel Layered Structure CdSbX₃ (X = S and Se)

In this work, based on first-principles calculations and Boltzmann transport theory, we have investigated the structural, electronic, mechanical, and thermoelectric properties of \(\hbox {CdSbS}_{3}\) ${\text{CdSbS}}_3$ and \(\hbox {CdSbSe}_{3}\) ${\text{CdSbSe}}_3$ compounds, which are two novel members of the \(\hbox {MAX}_{3}\) ${\text{MAX}}_3$ family. We found that these compounds are semiconductors with a narrow band gap. In addition, they are both mechanically, dynamically, and thermodynamically stable. The results show that their interlayer distances are wider than almost all transition metal dichalcogenide compounds. Furthermore, we report that the lattice thermal conductivity, \(\kappa _{\text{l}}\) ${\kappa }_{\text{l}}$ , at room temperature for \(\hbox {CdSbS}_{3}\) ${\text{CdSbS}}_3$ is 0.53 W m⁻¹ K⁻¹ and 0.13 W m⁻¹ K⁻¹ for \(\hbox {CdSbSe}_{3}\) ${\text{CdSbSe}}_3$ . This latter value is similar to that of \(\hbox {ZnPSe}_{3}\) ${\text{ZnPSe}}_3$ , which was found to be lower than all other 2D materials. More remarkably, the thermoelectric figure of merit of \(\hbox {CdSbS}_{3}\) ${\text{CdSbS}}_3$ reaches as high as 2.34 at 1400 K and 2.68 for \(\hbox {CdSbSe}_{3}\) ${\text{CdSbSe}}_3$ at 850 K, which is a record high value at this temperature.