Defect Engineering in Solution-Processed Polycrystalline SnSe Leads to High Thermoelectric Performance

Abstract

SnSe has emerged as one of the most promising materials for thermoelectric energy conversion due to its extraordinary performance in its single-crystal form and its low-cost constituent elements. However, to achieve an economic impact, the polycrystalline counterpart needs to replicate the performance of the single crystal. Herein, we optimize the thermoelectric performance of polycrystalline SnSe produced by consolidating solution-processed and surface-engineered SnSe particles. In particular, the SnSe particles are coated with CdSe molecular complexes that crystallize during the sintering process, forming CdSe nanoparticles. The presence of CdSe nanoparticles inhibits SnSe grain growth during the consolidation step due to Zener pinning, yielding a material with a high density of grain boundaries. Moreover, the resulting SnSe–CdSe nanocomposites present a large number of defects at different length scales, which significantly reduce the thermal conductivity. The produced SnSe–CdSe nanocomposites exhibit thermoelectric figures of merit up to 2.2 at 786 K, which is among the highest reported for solution-processed SnSe.

The Importance of Surface Adsorbates in Solution‐Processed Thermoelectric Materials: The Case of SnSe

“…These contour plots delimit the areas where the concentration of Na is ≥2 at%. [ 56 ] We observe that in the pellet, Na is distributed in four different environments: i) within the crystal lattice; ii) at dislocations; iii) forming grain boundary complexions; [ 57 ] and iv) in nanoprecipitates [ 41 ] (Figure 3).…”

“…Precursors, solvent zT max SnSe-3%CdSe [41] SnCl 2 NaOH-Sn 1−x Se [30] SnCl 2 , Na 2 SeO 3 , NaOH, EG 1.5 (823 K, ⊥) Sn 0.882 Cu 0.118 Se [34] SnCl 2 SnSe-15%Te NWs [45] SnCl 2 2B). The Na to Sn ratio determined by X-ray photoemission spectroscopy (XPS, Figure S2, Supporting Information) is five times larger than that obtained from EDS (Figure S1, Supporting Information), suggesting that Na is mainly at the particle surface, yet we cannot discard its presence within the SnSe particles.…”

Kinetics and mechanistic details of bulk ZnO dissolution using a thiol–imidazole system

“…5,11 The alkahest solvent system returns functional thin lms that have proven useful in a multitude of applications, including solar cells, 17,18 photodetectors, 19 thermoelectrics, 20 neuromorphic devices, 21 electrocatalysts, 22 and it has also been used to engineer the surfaces of colloidal nanocrystals. [23][24][25] This approach has the potential to be translated to large-scale solution processing. 14 While the alkahest has been widely adopted for device fabrication because of the simplicity of the approach, the fundamental mechanism of oxide dissolution using this solvent couple has yet to be explored.…”

An Overview of the Strategies for Tin Selenide Advancement in Thermoelectric Application

“…SnSe displays an assembly of layered orthorhombic arrangements with a, b, c lattice parameters as 11.49 Å, 4.44 Å, and 4.135 Å, respectively, forming the normally largest axis of a bi-planar layered structure [72][73][74]. There are three adjacent Sn atoms covalently bonded with each tin atom, and so on.…”