Near stoichiometric-ratio Mg3Sb2 thermoelectric thin films fabricated via multi-step annealing strategies

Recently, Zintl Mg₃Sb₂-based compounds have attracted attention due to high thermoelectric performance, but most studies are concentrated on bulk materials with few on films and devices, limiting their applications for microelectronics. Here, p-type Mg₃Sb₂ films near stoichiometric-ratio are successfully fabricated using the multi-step experimental strategies based on the magnetron sputtering method. By tuning the energy structure and carrier transport, their thermoelectric performance is significantly improved, with a power factor up to 258.64 μW m⁻¹ K⁻² at ∼623 K. A Mg₃Sb₂-based generator is fabricated using these films, representing the first report of such a device. The output performance of this generator is evaluated and its power density is found to reach 9.4 μW cm⁻² at ΔT of 40 K, showing good potential for powering electronics. Furthermore, the generator shows good stability with no significant change in output properties after storage in air for 40 days or over periodic cycles of high- and room-temperature operation.