Materials and Nanoscience, Nebraska Center for (NCMN)


Date of this Version



Published in Materials Today Physics 37 (2023) 101211



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


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 CuCd1.01InSe3, 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 CuCd1.005InSe3, which is seven times higher than that of the pristine CuCdInSe3.

Includes supplemental materials

1-s2.0-S254252932300247X-mmc1.docx (23756 kB)
Luo MTP 2023 Entropy-driven structural transition SUPPLEMENTAL