Enhanced thermoelectric performance of Cu2Se realized by Ag2S doping

In this paper, Cu2Se samples doped with different concentrations of Ag2S were prepared by mechanical alloying and spark plasma sintering. Ag and S elements diffused during the preparation process and appeared aggregation in EDS mapping images. AgCuSe impurity phase can be observed in Cu2Se samples after Ag2S doping. Because of the enhanced scattering of the low- and mid-frequency phonons by AgCuSe nano inclusion, the total thermal conductivity of the Ag2S doped samples exhibits a significant decrease. Additionally, the diffusion and substitution of S can efficiently impede the formation of Cu vacancies. Ag ions can also fill the Cu vacancies, leading to the decreasing carrier concentration. Finally, the thermoelectric property is improved and the maximum ZT value similar to 1.5 is achieved at 820 K in Cu2Se/ 2% Ag2S, which is about 1.5 times of the undoped Cu2Se sample.

Automated summary

Cu2Se samples doped with different concentrations of Ag2S were prepared, and the Ag and S elements diffused during the preparation process. AgCuSe impurity phase was observed in the doped samples, leading to a significant decrease in thermal conductivity. Additionally, the diffusion and substitution of S impeded the formation of Cu vacancies, and Ag ions filled the vacancies, resulting in a decrease in carrier concentration. Ultimately, the thermoelectric property was improved, achieving a maximum ZT value of approximately 1.5 at 820 K in Cu2Se/2% Ag2S, which was 1.5 times higher than the undoped Cu2Se sample.