Improved thermoelectric properties of Ag-doped polycrystalline SnSe with facile electroless plating

Abstract

The thermoelectric (TE) performance of polycrystalline SnSe is limited by its low electrical properties, and normally doped with metals like Ag, Na etc by simply mixing with SnSe in melting. In this paper, a facile electroless plating is introduced to improve its TE performance for the first time. The results showed Ag was coated on the surface of SnSe powders homogeneously even after sintered with SPS. The influence of the Ag dopant on the electrical and thermal transport is analyzed. The silver coating with electroless plating could obviously improve average power factor (nearly fourfold) with minor effects (only 13% enhancement) on thermal conductivity. Therefore, a peak ZT value of 0.68 is achieved at 873 K in 1.0% Ag doped SnSe parallel to SPS pressing direction. In addition, the anisotropic properties are also found in this Ag doping SnSe by electroless plating. Compared with sample along parallel direction in 0.5% Ag coating, the power factor along the perpendicular direction improves over 50%, and thermal conductivity only increases 12.35%, resulting in a ZT peak value of 0.85 at 873 K. Compared with traditional mixing method, electroless plating is a facile and more homogenous doping method, and could be an improved way for doping to finer tune other thermoelectric materials performance.