Giant Seebeck effect in Ge-doped SnSe.

M Gharsallah,J A Alonso,M T Fernández-Díaz,F Serrano-Sánchez,N M Nemes,F J Mompeán,J L Martínez,F Elhalouani

doi:10.1038/srep26774

Abstract

Thermoelectric materials may contribute in the near future as new alternative sources of sustainable energy. Unprecedented thermoelectric properties in p-type SnSe single crystals have been recently reported, accompanied by extremely low thermal conductivity in polycrystalline samples. In order to enhance thermoelectric efficiency through proper tuning of this material we report a full structural characterization and evaluation of the thermoelectric properties of novel Ge-doped SnSe prepared by a straightforward arc-melting method, which yields nanostructured polycrystalline samples. Ge does not dope the system in the sense of donating carriers, yet the electrical properties show a semiconductor behavior with resistivity values higher than that of the parent compound, as a consequence of nanostructuration, whereas the Seebeck coefficient is higher and thermal conductivity lower, favorable to a better ZT figure of merit.

Highlights

Thermoelectric effect allows the direct conversion of waste heat to useful electrical energy
In this report we describe a fast and straightforward preparation procedure of compact pellets of Sn1−xGexSe, by arc melting, leading to highly oriented polycrystalline specimens where Ge inclusion into the structure is confirmed by neutron powder diffraction (NPD) studies
A novel series of Ge-doped SnSe intermetallic compounds has been prepared by a straightforward procedure producing strongly nanostructured samples

Summary

Introduction

Thermoelectric effect allows the direct conversion of waste heat to useful electrical energy. A new material has drawn the attention of the thermoelectric scientific community, with the description of a record-high ZT value of 2.6 at 923 K in single crystalline SnSe semiconductor[12]. This compound had been known for a long time but its thermoelectric parameters were evaluated as poor[13,14]. By using Na as an effective acceptor an ultrahigh power factor was achieved for single-crystal SnSe in a broad temperature range[19,20] This material presents some disadvantages that could impede its application i) SnSe is difficult to prepare in single crystalline form, and hard to handle, as it is prone to cleave[12,21], ii) the preparation described for www.nature.com/scientificreports/

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