First-Principles Study of Strain Engineering Regulation of SnSe Thermoelectric Properties

To study the effect of strain engineering on the thermoelectric properties of SnSe, we combined first-principles calculation and Boltzmann transport theory to study the effect of -4% to 4% strain on SnSe thermoelectric properties. Compressive strain enhances the maximum power factor (<i>PF</i>_max) of p-type SnSe from 2.3 to 4.3 mW·m^-1·K^-2. Specifically, under a -3% compressive strain, the thermoelectric figure of merit (<i>ZT</i>) experiences a 50% enhancement, increasing from 0.18 to 0.27. Conversely, for n-type, tensile strain leads to a 26% rise in the <i>PF</i>ₘₐₓ, from 53.6 to 67.6 mW·m^-1·K^-2. Notably, the 4% tensile strain increased the <i>ZT</i> value of n-type SnSe by 123% from 0.66 to 1.47. Importantly, tensile strain effectively reduces lattice thermal conductivity through enhanced phonon scattering, synergistically improving <i>ZT</i> with the enhanced power factor. The results show that strain can effectively improve the thermoelectric properties of SnSe, and that n-type SnSe has great potential in thermoelectric materials.