Blocking Ion Migration Stabilizes the High Thermoelectric Performance in Cu2Se Composites

Dongwang Yang, Xianli Su, Jun Li, Hui Bai, Shanyu Wang, Zhi Li, Hao Tang, Kechen Tang, Tingting Luo, Yonggao Yan, Jinsong Wu, Jihui Yang, Qingjie Zhang, Ctirad Uher, Mercouri G. Kanatzidis, Xinfeng Tang*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

109 Scopus citations


The applications of mixed ionic–electronic conductors are limited due to phase instability under a high direct current and large temperature difference. Here, it is shown that Cu2Se is stabilized through regulating the behaviors of Cu+ ions and electrons in a Schottky heterojunction between the Cu2Se host matrix and in-situ-formed BiCuSeO nanoparticles. The accumulation of Cu+ ions via an ionic capacitive effect at the Schottky junction under the direct current modifies the space-charge distribution in the electric double layer, which blocks the long-range migration of Cu+ and produces a drastic reduction of Cu+ ion migration by nearly two orders of magnitude. Moreover, this heterojunction impedes electrons transferring from BiCuSeO to Cu2Se, obstructing the reduction reaction of Cu+ into Cu metal at the interface and hence stabilizes the β-Cu2Se phase. Furthermore, incorporation of BiCuSeO in Cu2Se optimizes the carrier concentration and intensifies phonon scattering, contributing to the peak figure of merit ZT value of ≈2.7 at 973 K and high average ZT value of ≈1.5 between 400 and 973 K for the Cu2Se/BiCuSeO composites. This discovery provides a new avenue for stabilizing mixed ionic–electronic conduction thermoelectrics, and gives fresh insights into controlling ion migration in these ionic-transport-dominated materials.

Original languageEnglish (US)
Article number2003730
JournalAdvanced Materials
Issue number40
StatePublished - Oct 1 2020


  • Cu Se
  • Schottky junction
  • mixed ionic–electronic conductors
  • stable thermoelectric materials
  • thermoelectric properties

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • General Materials Science


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