Temperature-dependent AC conductivities of BiCuOCh (Ch = Te, Se) in the terahertz range

•BiCuOCh exhibit high efficiency in thermoelectric cooling and power generation.•Conductivity of BiCuO compounds with Te and Se were investigated in THz region.•Carrier dynamics of BiCuOTe and BiCuOSe can be explained by band structure.•Drude-Smith model is used to explain non Drude behavior.

We investigated the temperature-dependent optical conductivity of BiCuOCh (Ch = Te, Se) in the terahertz (THz) region. The optical conductivity of BiCuOSe increases with the temperature from 297 to 600 K, whereas that of BiCuOTe exhibits a different trend. In the THz frequency range of 0.4–1.6 THz, these materials show a conductivity increase as the frequency increases. The conductivity of BiCuOTe is greater than that of BiCuOSe. These results can be explained by a two-band structure model and the carrier-carrier scattering process. In addition, we fitted the experimental results to the Drude–Smith model to explain non-Drude like behavior. The dielectric constant of BiCuOTe depends on the frequency rather than on the temperature, whereas that of BiCuOSe depends on the temperature.