# Tuning the electronic structures and transport coefficients of Janus PtSSe monolayer with biaxial strain

## TL;DR

This study systematically investigates how biaxial strain affects the electronic structures and transport properties of Janus PtSSe monolayer, revealing strain-induced enhancements in thermoelectric performance and the impact of spin-orbit coupling.

## Contribution

It provides a detailed analysis of strain effects on PtSSe monolayer's electronic and transport properties, highlighting the role of SOC and strain in optimizing thermoelectric performance.

## Key findings

- SOC reduces power factor by affecting energy bands near the Fermi level.
- Compressive strain enhances conduction band convergence and increases Seebeck coefficient.
- PtSSe monolayer remains mechanically stable under studied strain range.

## Abstract

Due to their great potential in electronics, optoelectronics and piezoelectronics, Janus transition metal dichalcogenide (TMD) monolayers have attracted increasing research interest, the MoSSe of which with sandwiched S-Mo-Se structure has been synthesized experimentally. In this work, the biaxial strain dependence of electronic structures and transport properties of Janus PtSSe monolayer is systematically investigated by using generalized gradient approximation (GGA) plus spin-orbit coupling (SOC). Calculated results show that SOC has a detrimental effect on power factor of PtSSe monolayer, which can be understood by considering SOC effects on energy bands near the Fermi level. With $a/a_0$ from 0.94 to 1.06, the energy band gap firstly increases, and then decreases, which is due to the position change of conduction band minimum (CBM). It is found that compressive strain can increase the strength of conduction bands convergence by changing relative position of conduction band extrema (CBE), which can enhance n-type $ZT_e$ values. Calculated results show that compressive strain can also induce the flat valence bands around the $\Gamma$ point near the Fermi level, which can lead to high Seebeck coefficient due to large effective masses, giving rise to better p-type $ZT_e$ values. The calculated elastic constants with $a/a_0$ from 0.94 to 1.06 all satisfy the mechanical stability criteria, which proves that the PtSSe monolayer is mechanically stable in the considered strain range. Our works further enrich studies of Janus TMD monolayers, and can motivate farther experimental works.