Improvement of the thermoelectric performance of InSe-based alloys doped with Sn

Abstract

Here we present InSe-based alloys InSeSn_x (x = 0–0.02) with improved thermoelectric performance upon Sn's preferential occupation on In lattice sites. This improvement is attributed to the enhancement in carrier concentration (n) and reduction in lattice thermal conductivity (κ_L). However, the enhancement in n is limited due to the presence of the intermediate band in the middle of the bandgap, which acts as an annihilation center for electrons and holes. The reduction in κ_L is caused by increased phonon scattering on the newly-created defect Sn_In⁺. As a result, we attain the highest ZT value of 0.23 at x = 0.01@830 K, which is about 2.9 times that of virgin InSe.