Realizing high thermoelectric performance in magnetic field-assisted solution synthesized nanoporous SnSe integrated with quantum dots

Abstract

SnSe is considered as one of the most promising candidates for thermoelectric application because of its attractive performance recently. In this work, a high magnetic field (5 T) is applied during the solution synthesis process. With the assist of the high magnetic field, nanopores and quantum dots (Sn, Se) are induced in the Ga doped p-type polycrystalline SnSe. It is found that an ultralow lattice thermal conductivity of 0.19 W m−1 K−1 is caused by enhanced phonon scattering due to the presence of nanopores, quantum dots, lattice strain in dislocation networks. The enhanced density of states induced by Sn and Se quantum dots contributes to enhanced Seebeck coefficient. The enhanced electrical conductivity and Seebeck coefficient give rise to a significant enhancement in power factor over the whole temperature range. The maximum power factor reaches to 6.12 μW cm−1 K−2 at 873 K for the sample prepared under high magnetic field. Consequently, a peak ZT of 2.0 as well as a high average ZT of 0.74 (300–873 K) is achieved in 5 T-NP/QD Sn0.975Ga0.025Se sample. This study provides an important direction for developing high performance thermoelectric materials by structural manipulation with the aid of high magnetic field in solution chemistry.