# Phonon and electron transport in Janus monolayers based on InSe

## TL;DR

This study uses first-principles calculations to analyze phonon and electron transport in InSe monolayers and Janus derivatives, revealing their thermal and electronic properties relevant for device applications.

## Contribution

It provides a systematic comparison of phonon and electron transport in InSe and Janus In2SSe and In2SeTe monolayers, highlighting their potential for thermoelectric and electronic devices.

## Key findings

- Thermal conductivity varies among the materials, with In2SeTe having the lowest.
- Breaking mirror symmetry introduces a distinguishable Raman peak.
- In2SeTe shows higher electron mobility due to tensile strain.

## Abstract

We systematically investigated the phonon and electron transport properties of monolayer InSe and its Janus derivatives including monolayer In2SSe and In2SeTe by first-principles calculations. The breaking of mirror symmetry produce a distinguishable A1 peak in the Raman spectra of monolayer In2SSe and In2SeTe. The room-temperature thermal conductivity (\k{appa}) of monolayer InSe, In2SSe and In2SeTe is 44.6, 46.9, and 29.9 W/(m K), respectively. There is a competition effect between atomic mass, phonon group velocity and phonon lifetime. The \k{appa} can be further effectively modulated by sample size for the purpose of thermoelectric applications. Meanwhile, monolayer In2SeTe exhibits a direct band and higher electron mobility than that of monolayer InSe, due to the smaller electron effective mass caused by tensile strain on the Se side. These results indicate that 2D Janus group-III chalcogenides can provide a platform to design the new electronic, optoelectronic and thermoelectric devices.