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

Here we present InSe-based alloys InSeSnx (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 (kappa(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 kL 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.