New record high thermoelectric ZT of delafossite-based CuCrO2 thin films obtained by simultaneously reducing electrical resistivity and thermal conductivity via heavy doping with controlled residual stress

Dung Van Hoang, Anh Tuan Thanh Pham, Takahiro Baba, Truong Huu Nguyen, Thu Bao Nguyen Le, Thuy Dieu Thi Ung, Jongill Hong, Jong Seong Bae, Hongjun Park, Sungkyun Park, Isao Ohkubo, Takao Mori, Vinh Cao Tran, Thang Bach Phan

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

Defect engineering can effectively modulate the band structure of a thermoelectric (TE) material, thereby enhancing its power factor S2σ. Furthermore, residual stress engineering influences the film performance, especially in the planar technologies. For the TE Mg-doped CuCrO2-based materials, the limitations in achieving an outstanding figure of merit, ZT, arise from their characteristically low charge carrier mobility and high thermal conductivity. Herein, we propose a combination of defect engineering and stress engineering via heavy doping CuCr1-xMgxO2 with × = 0.15 at different deposition temperatures to overcome the aforementioned limitations. Combining the compressive residual stress with multiscale defects (point defects, grain boundaries, and nano-inclusions) significantly reduces the thermal conductivity (κ) to 0.44 W/mK. The σ of the films shows a remarkable enhancement because of point defects introduced via heavy doping. Notably, the compressive-stressed films exhibit higher ZT values, compared to the tensile-stressed films. As a result, an outstanding approximated ZT of 0.66 is observed in the compressive-stressed CuCr0.85Mg0.15O2 films, overcoming the limitations of its ZT value observed for the past two decades.

Original languageEnglish
Article number152526
JournalApplied Surface Science
Volume583
DOIs
Publication statusPublished - 2022 May 1

Bibliographical note

Publisher Copyright:
© 2022 Elsevier B.V.

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Surfaces and Interfaces

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