High Thermoelectric Performance of Cu₃SbSe₄ Obtained by Synergistic Modulation of Power Factor and Thermal Conductivity

In this work, Cu3–yAgySb1–xGexSe4 (x = 0, 0.04, 0.06, 0.08, 0.10, 0.12; y = 0, 0.1, 0.2, 0.3, 0.4) is fabricated using a high-temperature melting process, and the thermoelectric properties are investigated in the temperature range of 300–700 K. As a result, a remarkable improvement in thermoelectric performance of Cu-based ternary thermoelectric materials is achieved here. Ge doping increases the carrier concentration leading to a decrease in electrical resistivity; Ag alloying can reduce thermal conductivity significantly and enhance the power factor. Consequently, a maximum figure of merit, 0.95, is obtained for Cu2.7Ag0.3Sb0.94Ge0.06Se4 and Cu2.6Ag0.4Sb0.94Ge0.06Se4 at 700 K, which is higher than most reported Cu3SbSe4-based systems.