Achieving weak anisotropy in N-type I-doped SnSe polycrystalline thermoelectric materials

SnSe is a very strong anisotropic material; sometimes, strong anisotropy is unenviable for producing parts of thermoelectric (TE) devices. In order to study the efficient preparation of high-performance n-type poly-crystalline SnSe with weak anisotropy, in this work, we combine mechanical alloying at 450 RPM for 10 h and spark plasma sintering at 773 K under 50 MPa pressure for the preparation of polycrystalline SnSe 0.95-xIx (x = 0,0.01,0.02,0.03) samples, and investigate the TE properties. The prepared samples show very weak anisotropy. With iodine doping, increased carrier concentration is observed, in agreement with DFT calculations. A peak ZT approximate to 1.02 at 723 K is observed with I-doping of x = 0.02, which is about 225% higher than that of undoped sample with ZT approximate to 0.31 at 723 K in parallel direction, mainly attributed to the enhanced power factor and about 56% reduced thermal conductivity from 0.68 Wm- 1K-1 to 0.30 Wm- 1K-1. TE properties in both directions are not much different, and the ratios of electrical and thermal conductivities in both directions are very close to unity.

Automated summary

A study on the preparation of high-performance n-type polycrystalline SnSe using mechanical alloying and spark plasma sintering showed that iodine doping can increase carrier concentration and improve thermoelectric properties, leading to enhanced power factor and reduced thermal conductivity. The peak ZT of approximately 1.02 at 723 K with iodine doping of x = 0.02 was significantly higher than the undoped sample, demonstrating a potential for improved thermoelectric efficiency.