Exceptional Thermoelectric Performance of Cu2(Zn,Fe,Cd)SnS4 Thin Films

Yu Liu, Paul Mcnaughter, Xiaodong Liu, Andrey Kretinin, Jonathan Skelton, Feridoon Azough, David Lewis, Robert Freer

Research output: Contribution to journalArticlepeer-review

Abstract

High-quality Cu2(Zn,Fe,Cd)SnS4 (CZFCTS) thin films based on the parent CZTS were prepared by aerosol-assisted chemical vapour deposition (AACVD). Substitution of Zn by Fe and Cd significantly improved the electrical transport properties, and monophasic CZFCTS thin films exhibited a maximum power factor (PF) of ~0.22 μW cm-1 K-2 at 575 K. The quality and performance of the CZFCTS thin films were further improved by post-deposition annealing. CZFCTS thin films annealed for 24 h showed a significantly enhanced maximum PF of ~2.4 μW cm-1 K-2 at 575 K. This is higher than all reported values for single-phase quaternary sulfide (Cu2BSnS4, B = Mn, Fe, Co, Ni) thin films and even exceeds the PF for most polycrystalline bulk materials of these sulfides. Density functional theory (DFT) calculations were performed to understand the impact of Cd and Fe substitution on the electronic properties of CZTS. It was predicted that CZFCTS would have a smaller bandgap than CZTS and a higher density of states (DoS) near the Fermi level. The thermal conductivity and thermoelectric figure of merit (zT) of the CZFCTS thin films have been evaluated, yielding an estimated maximum zT range of 0.18-0.69 at 550 K. The simple processing route and improved thermoelectric performance makes CZFCTS thin films extremely promising for thermoelectric energy generation.
Original languageEnglish
JournalACS Applied Materials and Interfaces
Publication statusAccepted/In press - 8 Feb 2024

Keywords

  • Thermoelectrics
  • thin films
  • Cu2ZnSnS4 (CZTS)
  • Aerosol-assisted chemical vapour deposition (AACVD)
  • Fe and Cd doping
  • Density functional theory

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