Insight into Scattering Mechanisms and Transport Properties of AgCuS for Flexible Thermoelectric Applications

The development of flexible thermoelectric devices requires materials possessing ductility and high thermoelectric performance at room temperature. However, only a few existing materials meet both criteria. In this study, the ductile properties, electronic structure, and transport properties of the low-temperature phase α-AgCuS were elucidated using first-principles calculations combined with Boltzmann transport theory. With a layered zigzag structure similar to the well-known ductile semiconductor Ag₂S, AgCuS is determined to have good metal-like ductility. Through consideration of various intrinsic scattering mechanisms, we found that electron-polar optical phonon interactions have the most significant impact on the transport behavior of AgCuS. The predominance of this type of interaction is also disclosed by the covalent-ionic bonding nature of the Ag-S and Cu-S bonds. Therefore, weakening this interaction via doping or alloying could optimize the thermoelectric performance of the system. At room temperature, a maximum dimensionless figure of merit ZT of up to 0.592 could be achieved under a tuning of hole concentration to 2 × 10¹⁹ cm^-3, suggesting that α-AgCuS could be a promising p-type candidate for flexible thermoelectric applications.