Strain effect on electronic structure and thermoelectric properties of orthorhombic SnSe: A first principles study

Abstract

Strain effect on thermoelectricity of orthorhombic SnSe is studied using density function theory. The Seebeck coefficients are obtained by solving Boltzmann Transport equation (BTE) with interpolated band energies. As expected from the crystal structure, calculated Seebeck coefficients are highly anisotropic, and agree well with experiment. Changes in the Seebeck coefficients are presented, when strain is applied along b and c direction with strength from -3% to +3%, where influence by band gaps and band dispersions are significant. Moreover, for compressive strains, the sign change of Seebeck coefficients at particular direction suggests that the bipolar transport is possible for SnSe.

Engineering the Near-Edge Electronic Structure of SnSe through Strains

“…Unlike modifying materials properties though chemical means, strain-engineer enables active control of materials properties. We mention that although there have been previous DFTbased studies [21] of the strain effects on the electronic properties of SnSe, our GW results provide more accurate predictions which can be compared directly with experiment and guide future materials design.…”

“…Another important alternative is strain-engineering, which has long been used as an effective and predictable means for tuning the materials properties [11][12][13][14][15][16], including strain-induced structural phase transitions [17][18][19], indirect-direct band gap transition [11][12][13], and semiconductormetal transition [12,20]. Previous work [4,21,22] also demonstrated the possibility of applying strains to tune the thermoelectric power factor. The band edges of SnSe have several competing local extrema within a small energy window, and the wave functions of the electronic states near these local extrema have different atomic origins.…”

Coupling effects of strain on structural transformation and bandgap engineering in SnS monolayer

“…The mechanical properties of monolayer SnS still need further investigation. [31][32][33][34][35] In this paper, we investigate the structural, electronic and optical properties of monolayer SnS based on strain-inducedpotential energy surface (SIPES) and band proles (SIBP) within the density functional theory (DFT). The SIPES can be used to investigate not only the axial strain but also the coupling effect due to the anisotropic strain.…”

Quasi-two-dimensional thermoelectricity in SnSe

“…The record ZT figure of merit of p-type SnSe has been explained as arising from a valence band structure with multiple low-lying valleys, on the basis of band structure calculations [11,14] that have not been verified by ex- * Electronic address: grueneis@ph2.uni-koeln.de † Electronic address: thomas.szkopek@mcgill.ca periment. The role of dimensionality, long recognized as a critical factor in determining density of states and thus Seebeck coefficient [15], has thus far not been considered in the layered material SnSe.…”