Thermoelectric Performance of Tetrahedrite (Cu₁₂Sb₄S₁₃) Thin Films: The Influence of the Substrate and Interlayer

In the present work, tetrahedrite Cu₁₂Sb₄S₁₃ thin films were deposited on various substrates via aerosol-assisted chemical vapor deposition (AACVD) using diethyldithiocarbamate complexes as precursors. A buffer layer of Sb₂O₃ with a small lattice mismatch to Cu₁₂Sb₄S₁₃ was applied to one of the glass substrates to improve the quality of the deposited thin film. The buffer layer increased the coverage of the Cu₁₂Sb₄S₁₃ thin film, resulting in improved electrical transport properties. The growth of the Cu₁₂Sb₄S₁₃ thin films on the other substrates, including ITO-coated glass, a SiO₂-coated Si wafer, and mica, was also investigated. Compared to the films grown on the other substrates, the Cu₁₂Sb₄S₁₃ thin film deposited on the SiO₂-coated Si wafer showed a dense and compact microstructure and a larger grain size (qualities that are beneficial for carrier transport), yielding a champion power factor (PF) of ∼362 μW cm^-1 K^-2 at 625 K. The choice of substrate strongly influenced the composition, microstructure, and electrical transport properties of the deposited Cu₁₂Sb₄S₁₃ thin film. At 460 K, the highest zT value that was obtained for the thin films was ∼0.18. This is comparable to values reported for Cu-Sb-S bulk materials at the same temperature. Cu₁₂Sb₄S₁₃ thin films deposited using AACVD are promising for thermoelectric applications. To the best of our knowledge, the first full thermoelectric characterization of the Cu₁₂Sb₄S₁₃ thin film is performed in this work.