Effects of different LaCl3 doping processes on the thermoelectric properties of SnSe bulk materials

Both single crystal and polycrystalline SnSe have been widely investigated due to their superior thermoelectric properties in the medium temperature range. Due to its poor mechanical properties and complex and time-consuming synthesis process, single crystal SnSe is difficult to apply commercially. In this work, n-type polycrystalline SnSe with high thermoelectric properties was fabricated by LaCl 3 doping via the melting method combined with the spark plasma sintering (SPS) technique. Surprisingly, it was found that the different doping processes affect the electrical behavior of LaCl 3 -doped polycrystalline SnSe. The sample of LaCl 3 -doped SnSe was p-type when ball milling and the SPS technique were employed in our previous work, and the sample was n-type when the melting method and SPS were employed in this work. The doping mechanism was investigated in detail in this work.