Te-Embedded Nanocrystalline PbTe Thick Films: Structure and Thermoelectric Properties Relationship

The Te-embedded PbTe nanocrystallline thick films (i.e., 50 mu m) were electrodeposited, where the fraction and average grain size of PbTe and Te phases were tuned by adjusting the applied potential followed by post thermal treatment. The crystal grain boundary and Te nano-inclusion in the films played critical roles in their thermoelectric properties. The Te-embedded PbTe thick film with the average grain size of around 100 nm showed lower energy barrier height (E-B = 0.023 eV) than thick films with the average grain size of a few tens of nm (E-B = 0.11). Although decrease in the energy barrier reduced the Seebeck coefficient, however, it enhanced the electrical conductivity, which resulted in an increase in power factor (PF). The highest power factor was 183 mu w K-2 cm(-1), achieved at the energy barrier of 0.023 eV.