Attempts to realize promising thermoelectric performance in n-type polycrystalline SnSe with a cubic structure†

Abstract

Both crystalline and polycrystalline p-type SnSe have been investigated with promising thermoelectric capabilities across a broad temperature range, garnering significant attention recently. However, the inferior electrical transport of n-type polycrystalline SnSe, especially at low temperatures, has seriously restricted the advancement of thermoelectric devices based on SnSe. In the study, we attempted to attain promising thermoelectric properties of n-type polycrystalline SnSe through modulating the lattice structure by AgBiSe₂ alloying. After subsequent Br doping and Pb alloying, n-type polycrystalline SnSe with a cubic structure exhibited completely reversed electrical transport, especially at low temperatures (300–600 K). Resultantly, the polycrystalline (Sn_0.6Pb_0.4Se_0.97Br_0.03)_0.6(AgBiSe₂)_0.4 demonstrated promising thermoelectric properties, achieving a maximum ZT value of roughly 0.3 at 600 K, surpassing the performance of most other current n-type SnSe polycrystals. Our research presents a systematic method for obtaining n-type SnSe with a cubic-phase structure and promising performance, laying a basic foundation for constructing high-efficiency all-SnSe-based homogeneous thermoelectric devices.