Significantly improved thermoelectric performance of SnSe originating from collaborative adjustment between valence and conduction bands, mass fluctuations, and local strain

Abstract

In this study, environmentally friendly, low cost, and easy to synthesize In_Sn and V_Sn co-doped SnSe materials was designed and prepared via vacuum melting and spark plasma sintering technology, which avoids the shortcomings of high-performance Pb, Ge, and Na-doped SnSe samples. In_Sn and V_Sn, doping achieved appropriate bandgap (E_g) and energy band degeneracy (N_V) from the valence and conduction band, obtaining the highest electrical conductivity of 4726 S m⁻¹ at 773 K. The impurity state controls the carrier transport process below 573 K, while E_g and N_V control the process above 573 K. In_Sn and V_Sn doping induces quality fluctuation and local strain, which decreases the lattice thermal conductivity. Owing to the higher power factor and low lattice thermal conductivity, the ZT value of the Sn_0.985In_0.01Se sample was 1.3 at 773 K. Dual regulation of the valence and conduction band provides a new idea for adjusting the transport behavior of semiconductors.