Defect Engineering Boosted Ultrahigh Thermoelectric Power Conversion Efficiency in Polycrystalline SnSe

Abstract

Two-dimensional (2D)-layered atomic arrangement with ultralow lattice thermal conductivity and ultrahigh figure of merit in single-crystalline SnSe drew significant attention among all thermoelectric materials. However, the processing of polycrystalline SnSe with equivalent thermoelectric performance as singlecrystal SnSe will have great technological significance. Herein, we demonstrate a high zT of 2.4 at 800 K through the optimization of intrinsic defects in polycrystalline SnSe via controlled alpha irradiation. Through a detailed theoretical calculation of defect formation energies and lattice dynamic phonon dispersion studies, we demonstrate that the presence of intrinsically charged Sn vacancies can enhance the power factor and distort the lattice thermal conductivity by phonon-defect scattering. Supporting our theoretical calculations, the experimental enhancement in the electrical conductivity leads to a massive power factor of 0.9 mW/mK 2 and an ultralow lattice thermal conductivity of 0.22 W/mK through the vacancy-phonon scattering effect on polycrystalline SnSe. The strategy of intrinsic defect engineering of polycrystalline thermoelectric materials can increase the practical implementation of low-cost and high-performance thermoelectric generators.

Highly oriented platinum/iridium thin films for high-temperature thermocouples with superior precision

“…It is known that electron transport is directly related to the grain size, boundaries and contact interfaces. 14 Thus, the excellent stability of the Pt/Ir TFTCs are attributed to the same highly preferred orientation. V = a Δ T 3 + b Δ T 2 + c Δ T + d .…”

Thermoelectric Property of SnSe Films on Glass Substrate: Influence of Columnar Grain Boundary on Carrier Scattering

“…The existence of grain boundaries is characteristic of SnSe films on a glass substrate. Carrier scattering is very important for thermoelectric properties. , Scattering by acoustic phonons and optical phonons (nonpolar/polar) and by ionized impurities has been theoretically discussed for SnSe. , Carrier scattering by acoustic phonons, , defects, , and nanopore boundaries has been discussed experimentally. Grain boundaries significantly affect the carrier scattering in polycrystalline SnSe, − as is observed in other thermoelectric materials .…”

Energy Interplay in Materials: Unlocking Next‐Generation Synchronous Multisource Energy Conversion with Layered 2D Crystals

“…[66] 2D crystals have recently been found to possess extremely high thermoelectric figures of merit (ZT), in particular, 2D tin selenide (SnSe) crystals (ZT ≈ 2.62 at 923 K) [67] and defectengineered 2D SnSe (ZT ≈ 2.4 at 800 K) crystals. [68] The reason for the high ZT in 2D crystals is likely due to the anharmonic bonding and poor interlayer interactions that result in very low thermal conductivity. [67] Stacked 2D crystal heterostructures can exhibit much lower out-of-plane thermal conductivity due to vibrational mismatch and increased interlayer spacing, [69] and thus can have higher ZT.…”