Bipolar Thermoelectrical Transport of SnSe Nanoplate in Low Temperature

Bulk SnSe is an excellent thermoelectrical material with the highest figure-of-merit value of ZT = 2.8, making it promising in applications. Temperature-dependent electrical and thermoelectrical properties of SnSe nanoplates are studied at low temperature. Conductivity drops and rises again as temperature is lowered. The Seebeck coefficient is positive at room temperature and becomes negative at low temperature. The change of the sign of the Seebeck coefficient indicates influence of bipolar transport of the semiconductive SnSe nanoplate. The bipolar transport is caused by the Fermi energy changing with temperature due to different contributions from donors and acceptors at different temperatures.