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

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 Sn0.965Se microplates by using CrCl3. Cl- ions to trigger Sn-vacancy formation and optimize the hole concentration to approximate to 3 x 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 approximate to 0.2 W m(-1) K-1 in the as-sintered polycrystal, contributing to a high ZT of approximate to 2.4 at 823 K and an average ZT of approximate to 1.1. Of particular note, the polycrystal exhibits high hardness (approximate to 2.26 GPa) and compression strength (approximate to 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 approximate to 10% by a temperature difference of 425 K, indicating great potential for applying to practical thermoelectric devices.