Stability, Tunneling Characteristics and Thermoelectric Properties of TeSe2 allotropes

TL;DR

This study investigates the stability, electronic properties, and thermoelectric performance of various TeSe2 allotropes, revealing a new direct band gap phase with high thermoelectric efficiency suitable for energy applications.

Contribution

The paper introduces a new TeSe2 allotrope with a direct band gap and demonstrates its high thermoelectric figure of merit through first-principle calculations.

Findings

{ extquoteright}delta{-}TeSe2 has a 1.60 eV direct band gap.

Room temperature ZT can reach 3.1 with p-type doping.

Thermoelectric performance can be enhanced by tuning temperature and chemical potential.

Abstract

The waste heat management becomes very important with increasing energy demand and limited fossil resources. Here, we demonstrate thermoelectric performance of allotropic TeSe2. Based on the first-principle calculations, we confirm the energetic and kinetic stability of five TeSe2 allotropes. We predict {\delta}-TeSe2 as a new direct band gap semiconductor having 1.60 eV direct band gap. All the TeSe2 allotropes exhibit band gap in UV-Vis region. The structural phases are clearly distinguished using simulated scanning tunnel microscopy. The room temperature Seebeck coefficient is maximum of 4 V/K for {\delta}-TeSe2. We show that room temperature thermoelectric figure of merit (ZT) can reach up to 3.1 with p-type doping in {\delta}-TeSe2. Moreover, temperature and chemical potential tuning extends the thermoelectric performance of TeSe2 allotropes. We strongly believe that our study is compelling from an experimental perspective and holds a key towards fabrication of thermoelectric devices based on TeSe2.