Thermoelectric properties of layered oxyselenides with 3d transition metal ions

Layered oxychalcogenides have received extensive attention in the fields of magnetism, superconductivity, lithium battery, and luminescence due to their unique electronic, magnetic properties, and layered structure, among which layered oxyselenides have excellent and promising thermoelectric performance, such as BiCuSeO and Bi2LnO4Cu2Se2. Here, we successfully synthesized Sr2MO2Cu2Se2 (M = Co, Ni, Zn) and Sr2FeO3CuSe and investigated the thermoelectric properties at a wide temperature range (298–923 K). They have a relatively high Seebeck coefficient (>300 μV K−1) in medium to high temperature range and possess a low thermal conductivity. The power factor and ZT reach 65 μW m−1 K−1 and 0.07 at 923 K for intrinsic Sr2NiO2Cu2Se2, and a higher performance is expected to be achieved by strategies like carrier concentration optimization and band structure engineering.