Superior thermoelectric properties and ultralow thermal conductivity of 2D topological jacutingaite M₂M’X₃ (M = Ni, Pd, or Pt; M’ = Zn, Cd, or Hg; X = S, Se, or Te) family

Two-dimensional thermoelectric materials offer a sustainable solution to the challenges of an ever-increasing global demand for energy. Recently, topological materials have been demonstrated to possess excellent thermoelectric properties due to their unconventional electronic structure and unique boundary states. In particular, the jacutingaite-family M₂M’X₃ (M = Ni, Pd, or Pt; M’ = Zn, Cd, or Hg; X = S, Se, or Te), has attracted research attention due to their high stability and topological phase. Using first-principles calculation under the hybrid functional approach coupled with the Boltzmann transport theory, we investigate the thermoelectric properties of the monolayer topological jacutingaite materials. Twelve materials manifest a topological insulating (TI) phase with bandgaps reaching up to 261.5 meV. Surprisingly, these 12 non-trivial materials exhibit good thermoelectric properties, with the figure-of-merit (ZT) reaching greater than 1.0 within the 100 K to 800 K temperature range. Moreover, the ZT of Ni₂HgTe₃ (p-type) and Pt₂HgTe₃ (n-type) reaches up to 3.6 and 4.6, respectively. The excellent thermoelectric properties are due to their high power factor and extremely low lattice thermal conductivity, resulting in superior thermoelectric performance compared to the most current state-of-the-art thermoelectric materials. Our findings provide a new playground of materials in which non-trivial topological properties with outstanding thermoelectric performance coexist.