A Solvothermal Synthetic Environmental Design for High‐Performance SnSe‐Based Thermoelectric Materials

Abstract SnSe is challenging to use in thermoelectric devices due to difficulties in simultaneously optimizing its thermoelectric and mechanical properties. Here, the authors show a unique solvothermal synthetic environmental design to fabricate super‐large and micro/nanoporous Sn 0.965 Se microplates by using CrCl 3 . Cl − ions to trigger Sn‐vacancy formation and optimize the hole concentration to ≈3 × 10 19 cm −3 , while the as‐formed Cr(OH) 3 colloidal precipitations act as “templates” to achieve micro/nanoporous features, leading to low lattice thermal conductivity of ≈0.2 W m −1 K −1 in the as‐sintered polycrystal, contributing to a high ZT of ≈2.4 at 823 K and an average ZT of ≈1.1. Of particular note, the polycrystal exhibits high hardness (≈2.26 GPa) and compression strength (≈109 MPa), strengthened by grain refinement and vacancy‐induced lattice distortions and dislocations; while a single‐leg device provides a stable output power (>100 mW) and conversion efficiency of ≈10% by a temperature difference of 425 K, indicating great potential for applying to practical thermoelectric devices.