Experimental and Ab Initio Study of Cu2SnS3 (CTS) Polymorphs for Thermoelectric Applications

Ketan Lohani,Ilya Sergueev,Himanshu Nautiyal,Paolo Scardi,Carlo Fanciulli,Narges Ataollahi,Martin Etter

doi:10.1021/acs.jpcc.0c09139

Abstract

Cu2SnS3 (CTS) is a medium-temperature, ecofriendly, p-type thermoelectric material known for phonon-glass-electron-crystal characteristic. In the present work, ordered and disordered CTS samples we...

Highlights

Thermoelectric (TE) materials attract increasing interest in applications involving thermal gradients for durable, noise-free, and scalable solid-state power generators and coolers.[1−4]Performing TE devices require an optimal combination of properties Seebeck coefficient (S), electrical conductivity (σ), and thermal conductivity (k) to maximize the figure of merit, zT = TS2σ/k
We have studied electronic and vibrational properties using density functional theory (DFT) and density functional perturbation theory (DFPT) simulations, respectively
The disordered CTS polymorph shows a better TE performance than the ordered and stable CTS phase, mainly because of an enhanced carrier concentration and ultralow thermal conductivity observed in the former phase

Summary

Introduction

Performing TE devices require an optimal combination of properties Seebeck coefficient (S), electrical conductivity (σ), and thermal conductivity (k) to maximize the figure of merit, zT = TS2σ/k. The Cu2SnS3 mineral phase was first reported in 1983, as a new sulfide with a triclinic structure (SG: P1).[8] It has been widely studied as an absorber material for photovoltaic devices owing to its high (∼104 cm−1) optical absorption coefficient and tunable band gap spanning from 0.7 to 1.6 eV.[9−13] In recent years, CTS has attracted interest from the TE community for its 3D hole conductive network and ultralow thermal conductivity, a so-called “phonon-glass-electroncrystal” characteristic.[14] At first, in 2016, Tan et al.[15] and Shen et al.[16] reported CTS as a potential TE material, using In and Zn doping, respectively. Other researchers have reported Mn,[17] Ni, Fe,[19] and Co20 doping to enhance the TE performance of CTS

Methods

Results

Conclusion