Enhancement of Power Factor for Inherently Poor Thermal Conductor Ag₈GeSe₆ by Replacing Ge with Sn

Abstract

Superionic argyrodites have been identified as thermoelectric materials with inherent ultralow lattice thermal conductivity because of liquid-like behavior of cations in a relatively larger unit cell. The major drawback for these as potential thermoelectric materials is low carrier concentration and low electrical conductivity, which however can be improved by controlling the compositions while keeping the advantageous poor thermal conductivity intact. Here, we report ∼8 times enhancement of thermoelectric power factor of Ag 8 GeSe 6 by replacing Ge with metallic Sn, at high temperatures. Thus, Ag 8 SnSe 6 has been demonstrated as an efficient thermoelectric material with ZT ∼ 0.62 at 623 K, even at a very low carrier concentration (∼10 16 cm −3 ). The extremely low thermal conductivity has been explained with weakly bonded Ag ions to rigid anion sublattice and presence of low-frequency Einstein optic modes, which provide the possibility of decoupling of charge and heat transport.

N-type thermoelectric Ag8SnSe6 with extremely low lattice thermal conductivity by replacing Ag with Cu

“…5a ). It is observed that the n H value enhances from 1.93 × 10 16 cm −3 at x = 0 to 8.61 × 10 16 cm −3 at x = 0.1, comparable to that reported by Acharya et al 50 Usually, the mobility μ decreases because of ionized impurity and carrier scattering. 51–53 However, the mobility μ in the present work is laying in the range of 1.17 × 10 2 cm 2 V −1 s −1 and 1.34 × 10 2 cm 2 V −1 s −1 when x value increases from 0 to 0.075 and remains almost unchanged, and then it drops as the x value exceeds 0.075.…”

Considering the Role of Ion Transport in Diffuson‐Dominated Thermal Conductivity

“…Here, the thermal and ionic transport, as well as the vibrational properties, of nine Ag + argyrodite compositions are investigated, some of which are promising high-efficiency thermoelectric materials. [25,[34][35][36] This work aims to decouple the influences of ionic transport, structural complexity, and anharmonicity on the vibrational character and corresponding thermal conductivity of these fast ion conductors. By experimentally quantifying ionic conductivity and thermal conductivity, in conjunction with state-of-the-art computational methods, we are able to address the following questions: 1) Are significant diffuson contributions to thermal conductivity present in the here investigated fast ionic conductors?…”

High Thermoelectric Performance of ZnO by Coherent Phonon Scattering and Optimized Charge Transport

“…[ 3 ] In the past few decades, many strategies have been employed to improve the zT value by improving α 2 σ through band engineering [ 4–8 ] and introducing resonant levels in the electron density of states by doping. [ 9,10 ] Meanwhile, nanostructuring, [ 11 ] nanocomposites, [ 12 ] complex crystal structuring, [ 13,14 ] and the phonon softening technique [ 15 ] have been employed to reduce κ tot . For power generation and refrigeration, various thermoelectric materials have been reported to have high zT ≥ 1, including Bi 2 Te 3 , [ 16,17 ] PbTe, [ 18,19 ] SnTe, [ 20,21 ] SnSe, [ 22 ] and SiGe.…”