Biaxial Tensile Strain Enhances Thermoelectric Performance in SrAgISe Monolayer via First‐Principles Calculation

Abstract

Thermoelectric (TE) materials enable direct conversion between thermal and electrical energy, but their conversion efficiency still requires further improvement. Strain engineering has become an effective strategy to modulate the properties of two‐dimensional thermoelectric materials. In this work, we employed first‐principles calculations to investigate the thermoelectric properties of monolayer SrAgISe under biaxial tensile strain ranging from 0% to −6%. At 300 K, the pristine SrAgISe monolayer exhibits an intrinsic k l of 0.75 W m −1  K −1 and achieves a ZT max of 1.05 under n ‐type doping. Under 6% tensile strain, strain‐induced structural distortion enhances phonon scattering and softens phonon modes, reducing the k l value to 0.19 W m −1  K −1 and increasing the ZT max of n ‐type SrAgISe to 4.66. Moreover, for the unstrained intrinsic structure with SOC included, our calculations reveal a splitting of the valence band at the Γ point, along with a reduced hole effective mass and an enhanced hole mobility. At 300 K, the calculated p ‐type ZT max is approximately 29.79% higher than that obtained without SOC. This work demonstrates that biaxial tensile strain is an effective strategy to improve the thermoelectric performance of the SrAgISe monolayer. At the same time, the inclusion of SOC is necessary for a more accurate description of its electronic structure and calculated transport properties.