General design of high-performance and textured layered thermoelectric materials via stacking of mechanically exfoliated crystals

Abstract

Layered materials exhibit potential for thermoelectric applications, which are reliant on microstructural texture for high performance. In this work, we present layered crystal stacking hot deformation (LCSHD), which leverages anisotropic crystal structures to induce rapid texture formation, leading to high thermoelectric performance. Taking n-type bismuth telluride (Bi₂Te₃) as a representative, the LCSHD method contributed to a record-high power factor (PF) of 45 μW cm⁻¹ K⁻² in polycrystals. Additionally, the dislocation tangle and low-angle grain boundary can be found in the LCSHD sample, producing low lattice thermal conductivity and a remarkable ZT value of 1.2. Benefiting from a reliable high ZT, we prepared a seven-pair Bi₂Te₃-based module, which displayed an extraordinary conversion efficiency of 6.4% and competitive refrigeration performance. In addition, a significant improvement of ZT value in other layered materials, including SnSe₂ and SnSe, was also demonstrated. Our finding offers novel avenues for texture engineering, facilitating the design of high-performance layered thermoelectric materials.