Entropy-driven structural transition from Tetragonal to Cubic phase: High Thermoelectric Performance of CuCdInSe₃ compound

Authors

Tingting Luo, Wuhan University of Technology
Yihao Hu, Zhejiang University, Hangzhou
Shi Liu, Westlake University, Hangzhou
Fanjie Xia, Wuhan University of Technology
Junhao Qiu, Wuhan University of Technology
Haoyang Peng, Wuhan University of Technology
Keke Liu, Wuhan University of Technology
Quansheng Guo, Hubei University, Wuhan
Xingzhong Li, University of Nebraska - LincolnFollow
Dongwang Yang, Wuhan University of Technology
Xianli Su, Wuhan University of TechnologyFollow
Jinsong Wu, Wuhan University of TechnologyFollow
Xinfeng Tang, Wuhan University of TechnologyFollow

Date of this Version

2023

Citation

Published in Materials Today Physics 37 (2023) 101211

doi:10.1016/j.mtphys.2023.101211

Comments

Copyright © 2023. Published by Elsevier Ltd. Used by permission.

Abstract

Cu based chalcopyrite is an important class of thermoelectric materials with excellent electronic properties, however, the thermal conductivity is relatively high due to the simple tetragonal structure with highly ordered configuration on cation sites, limiting the thermoelectric performance. Herein, we realize that the modulation of entropy via alloying CdSe achieves the structural transition from tetragonal structure with ordered configuration on cations sites in CuInSe₂ compound to cubic CuCdInSe₃. CuCdInSe₃ crystallizes in a zinc blende (ZnS) structure where Cu, Cd and In cations randomly occupy the Zn site with the occupancy fraction 1/3. This entropy driven order-disorder transition on the cation site, in conjunction with the intensified point defect phonon scattering via alloying CdSe in CuInSe₂, dramatically suppress the thermal conductivity. An ultra-low thermal conductivity of 0.76 Wm^–1K^–1at 780 K is achieved for CuCdInSe₃ compound, which is only about 2/3 in comparison with that of CuInSe₂. CuCdInSe₃ is an indirect semiconductor, with the minimum of conduction band (CBM) located at Γ point and the maximum of valence band (VBM) between Γ and A. The density of states in VBM of CuCdInSe₃ are mainly contributed by the hybridization between Se-4p and Cu-3d orbitals, while that of CBM is dominant by Se- 4p and In-5s orbitals. Minute adjustment of Cd content in CuCd_(1+x)InSe₃ effectively modulates the carrier concentration and an optimized power factor of 0.58 Wm^–1K^–2 is attained at 578 K for CuCd_1.01InSe₃, which is 9.6 times as high as the pristine CuCdInSe₃. The improved electronic properties integrated with the intrinsically low thermal conductivity result in an enhanced thermoelectric figure-of-merit ZT value of 0.45 at 780 K for CuCd_1.005InSe₃, which is seven times higher than that of the pristine CuCdInSe₃.

Includes supplemental materials