Ordered grain boundary reconstruction induces high-efficiency thermoelectric power generation in SnTe

Abstract

The vast majority of research on eco-friendly mid-temperature SnTe thermoelectrics has focused solely on improving material performance, often neglecting effective module design. Consequently, constructing high-efficiency thermoelectric devices has posed tremendous challenges. Here, we propose an innovative strategy of “ordered grain boundary reconstruction” in SnTe materials. This strategy induces a robust energy filtering effect and significantly suppresses the high-temperature bipolar diffusion. As a result, it not only enhances the power factor at higher temperatures but also reduces lattice thermal conductivity to ∼0.4 W m⁻¹ K⁻¹ at 850 K, yielding a remarkable average zT of ∼1.0 from 300 to 850 K in Sn_0.88Mn_0.12Sb_0.16Te_1.24 + 0.05Sn sample. Notably, we successfully fabricated seven pairs of devices utilizing p-type SnTe and n-type PbSe for the first time, achieving a conversion efficiency as high as ∼10.5% and an ultra-high output power density of ∼2.0 W cm⁻² at a temperature difference of 461 K. Both of these values set new records for SnTe-based devices. This work not only provides valuable insights into the extraordinary role of ordered reconstruction structures at grain boundaries, but also overcomes the technical hurdles in high-efficiency SnTe-based device fabrication, thereby paving the way for advancements in other thermoelectrics.