High Carrier Mobility as a Key Factor for Thermoelectric Performance in Janus PdSSe Monolayer

ABSTRACT

Janus two‐dimensional materials with intrinsic out‐of‐plane asymmetry provide a promising platform for achieving enhanced thermoelectric performance. Here, the thermoelectric properties of the Janus PdSSe monolayer are investigated using first‐principles calculations combined with semiclassical Boltzmann transport theory. The PdSSe monolayer is confirmed to be energetically, dynamically, and thermally stable, exhibiting no imaginary phonon modes and maintaining robust structural integrity at ambient conditions. It also exhibits nearly isotropic mechanical behavior and good flexibility. Electronic structure calculations reveal an indirect band gap of 0.92 eV (PBE) and 1.43 eV (HSE). Notably, its high electron mobility (>2000 cm ² V ^{− 1} s ^{− 1} ), together with favorable band‐edge transport characteristics, contributes to enhanced electrical conductivity while maintaining a sizable Seebeck coefficient (≈1450 µV K ^{− 1} ). This balanced transport behavior results in a power factor of 73.5 mW/mK ² and a maximum ZT value of 0.81 at 900 K, corresponding to a thermoelectric conversion efficiency of 11.78%. These results suggest that mobility‐enhanced carrier transport plays a dominant role in the thermoelectric performance of the Janus PdSSe monolayer, providing useful insight for the design of high‐efficiency Janus thermoelectric materials.