| Popis: |
Tin selenide materials have attracted much attention due to the intrinsic low thermal conductivity. However, the further application of SnSe materials is limited due to the poor electrical conductivity. Herein, a two-step doping process is employed on p-type polycrystalline SnSe materials to enhance the thermoelectric properties. It is found that the Sn0·98Ag0.01Ga0.01Se sample achieves a high ZT value of 1.53 at 823 K and a quite competitive ZTave value of 1.04 from 673 to 823 K. This is attributed to the associations of point defects, AgSn′, GaSn·, and Ga0, and nano-precipitates, SnGa4Se7, Ag9GaSe6 and AgGa1+δ. In those defects, AgSn′ acts as an accepter, which can conduce to enhancing the hole carrier concentration. Ga element doping astonishingly play dual-roles, in that it both faultlessly maintains the electrical transport properties and effectively decreases the thermal conductivity through the associations with the point defects, GaSn·, and Ga0, and nano-precipitates, SnGa4Se7, Ag9GaSe6 and AgGa1+δ. The method paves the way for achieving high thermoelectric properties in SnSe materials by the point defects engineering and nano-precipitates. |
