Thermoelectric Properties of Cu₂Te Nanoparticle Incorporated N-Type Bi₂Te_2.7Se_0.3

To develop highly efficient thermoelectric materials, the generation of homogeneous heterostructures in a matrix is considered to mitigate the interdependency of the thermoelectric compartments. In this study, Cu₂Te nanoparticles were introduced onto Bi₂Te_2.7Se_0.3 n-type materials and their thermoelectric properties were investigated in terms of the amount of Cu₂Te nanoparticles. A homogeneous dispersion of Cu₂Te nanoparticles was obtained up to 0.4 wt.% Cu₂Te, whereas the Cu₂Te nanoparticles tended to agglomerate with each other at greater than 0.6 wt.% Cu₂Te. The highest power factor was obtained under the optimal dispersion conditions (0.4 wt.% Cu₂Te incorporation), which was considered to originate from the potential barrier on the interface between Cu₂Te and Bi₂Te_2.7Se_0.3. The Cu₂Te incorporation also reduced the lattice thermal conductivity, and the dimensionless figure of merit ZT was increased to 0.75 at 374 K for 0.4 wt.% Cu₂Te incorporation compared with that of 0.65 at 425 K for pristine Bi₂Te_2.7Se_0.3. This approach could also be an effective means of controlling the temperature dependence of ZT, which could be modulated against target applications.