Thermoelectric Properties of Hot-Pressed Bi-Doped n-Type Polycrystalline SnSe

Abstract

ᅟWe report on the successful preparation of Bi-doped n-type polycrystalline SnSe by hot-press method. We observed anisotropic transport properties due to the (h00) preferred orientation of grains along the pressing direction. The electrical conductivity perpendicular to the pressing direction is higher than that parallel to the pressing direction, 12.85 and 6.46 S cm−1 at 773 K for SnSe:Bi 8% sample, respectively, while thermal conductivity perpendicular to the pressing direction is higher than that parallel to the pressing direction, 0.81 and 0.60 W m−1 K−1 at 773 K for SnSe:Bi 8% sample, respectively. We observed a bipolar conducting mechanism in our samples leading to n- to p-type transition, whose transition temperature increases with Bi concentration. Our work addressed a possibility to dope polycrystalline SnSe by a hot-pressing process, which may be applied to module applications.Highlights We have successfully achieved Bi-doped n-type polycrystalline SnSe by the hot-press method.We observed anisotropic transport properties due to the [h00] preferred orientation of grains along pressing direction.We observed a bipolar conducting mechanism in our samples leading to n- to p-type transition. Electronic supplementary materialThe online version of this article (10.1186/s11671-018-2500-y) contains supplementary material, which is available to authorized users.

High‐Performance Thermoelectric SnSe: Aqueous Synthesis, Innovations, and Challenges

“…Among the state‐of‐the‐art thermoelectric materials, tin selenide (SnSe) is one of the most promising candidates to apply to thermoelectric devices due to its environmentally friendly feature, high cost‐effectiveness, and outstanding thermoelectric performance derived from its appropriate bandgap of ≈0.9 eV and intrinsic low κ l 9,10 . Figure a shows the development timeline for all SnSe‐based bulk thermoelectric materials,11–124 from which a record high ZT of ≈2.8 at 773 K was found in the n‐type SnSe single crystal,11 derived from its ultralow κ l of ≈0.18 W m −1 K −1 and high S 2 σ of ≈9.0 µW cm −1 K −2 at this temperature 125. Such a high ZT is also very competitive to other state‐of‐the‐art thermoelectric systems which possess ZTs > 2, such as PbTe,126–134 GeTe,135–147 Cu 2 Se/Cu 2 S,148–157 and AgSbTe 2 158.…”

“…A summary of ZTs for SnSe‐based thermoelectric materials. a) The timeline for state‐of‐the‐art SnSe bulks thermoelectric materials,11–124,169–182 the performance achieved by solution route are circled by yellow. b) Temperature‐dependent ZT and c) corresponding peak and average ZT values for polycrystalline SnSe through different fabrication techniques 13,16,22,46,58,62,95,99,101.…”

Modelling a Segmented Skutterudite-Based Thermoelectric Generator to Achieve Maximum Conversion Efficiency

“…X-ray Powder Diffraction (XRPD) is used for the phase identification of the crystals. The sample undergoes compaction through either spark plasma sintering [30,38,39], a cold pressed technique [40,41], a hot pressed method [42,43], or Arc melting [26]. Furthermore, a diamond saw blade is used to cut the compacted samples (pellets) into appropriate disc shapes and prismatic bars.…”

Composition change-driven texturing and doping in solution-processed SnSe thermoelectric thin films

“…However, SnSe single crystals have faced two major challenges due to these structural characteristics. First, this type of crystallographic feature has poor mechanical properties, which limits the practical applications of this material 15 . Second, at temperatures below ~800 K, SnSe single crystals with the Pnma space group have low carrier concentrations leading to poor TE properties.…”

“…Accordingly, significant efforts have been devoted to improving the mechanical properties by preparing SnSe polycrystals using hot-pressing 15–19 or spark plasma sintering 20–26 , however, these polycrystals typically have ZT values below 1. The low ZT values are likely due to the anisotropic TE properties of SnSe single crystals (low ZT of 0.8 along the a -axis) 15–26 .…”