Premium
High Thermoelectric Performance through Crystal Symmetry Enhancement in Triply Doped Diamondoid Compound Cu 2 SnSe 3
Author(s) -
Hu Lei,
Luo Yubo,
Fang YueWen,
Qin Feiyu,
Cao Xun,
Xie Hongyao,
Liu Jiawei,
Dong Jinfeng,
Sanson Andrea,
Giarola Marco,
Tan Xianyi,
Zheng Yun,
Suwardi Ady,
Huang Yizhong,
Hippalgaonkar Kedar,
He Jiaqing,
Zhang Wenqing,
Xu Jianwei,
Yan Qingyu,
Kanatzidis Mercouri G.
Publication year - 2021
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.202100661
Subject(s) - materials science , seebeck coefficient , thermoelectric effect , doping , condensed matter physics , phonon scattering , thermoelectric materials , effective mass (spring–mass system) , phonon , crystal structure , thermal conductivity , electrical resistivity and conductivity , crystallography , analytical chemistry (journal) , optoelectronics , composite material , chemistry , physics , quantum mechanics , thermodynamics , engineering , chromatography , electrical engineering
The presence of high crystallographic symmetry and nanoscale defects are favorable for thermoelectrics. With proper electronic structures, a highly symmetric crystal tends to possess multiple carrier channels and promote electrical conductivity without sacrificing Seebeck coefficient. In addition, nanoscale defects can effectively scatter acoustic phonons to suppress thermal conductivity. Here, it is reported that the triple doping of Cu 2 SnSe 3 leads to a high ZT value of 1.6 at 823 K for Cu 1.85 Ag 0.15 (Sn 0.88 Ga 0.1 Na 0.02 )Se 3 , and a decent average ZT ( ZT ave ) value of 0.7 is also achieved for Cu 1.85 Ag 0.15 (Sn 0.93 Mg 0.06 Na 0.01 )Se 3 from 475 to 823 K. This study reveals: 1) Ag doping on Cu sites generates numerous point defects and greatly decreases lattice thermal conductivity. 2) Doping Mg or Ga converts the monoclinic Cu 2 SnSe 3 into a cubic structure. This symmetry enhancing leads to an increase in the effective mass from 0.8 m e to 2.6 m e ( m e , free electron mass) and the power factor from 4.3 µW cm −1 K −2 for Cu 2 SnSe 3 to 11.6 µW cm −1 K −2 . 3) Na doping creates dense dislocation arrays and nanoprecipitates, which strengthens the phonon scattering. 4) Pair distribution function analysis shows localized symmetry breakdown in the cubic Cu 1.85 Ag 0.15 (Sn 0.88 Ga 0.1 Na 0.02 )Se 3 . This work provides a standpoint to design promising thermoelectric materials by synergistically manipulating crystal symmetry and nanoscale defects.