Figure of merit of EVERREDtronics Thermoelectric devices
The figure of merit for thermoelectric devices is defined as where σ is the electrical conductivity, κ is the thermal conductivity, and S is the Seebeck coefficient or thermopower (conventionally in μV/K). This is more commonly expressed as the dimensionless figure of merit ZT by multiplying it with the average temperature ((T2 + T1) / 2). Greater values of ZT indicate greater thermodynamic efficiency, subject to certain provisions, particularly the requirement that the two materials of the couple have similar
Z values. ZT is therefore a very convenient figure for comparing the potential efficiency of devices using different materials. Values of ZT=1 are considered good, and values of at least the 3–4 range are considered to be essential for thermoelectrics to compete with mechanical generation and refrigeration in efficiency. To date, the best reported ZT values have been in the 2–3 range.
Much research in thermoelectric materials has focused on increasing the Seebeck coefficient and reducing the thermal conductivity, especially by manipulating the nanostructure of the materials.
S , σ , κ Value Range of Everredtronics Thermoelectric Material |
S (μV/K) |
185 |
190 |
195 |
200 |
205 |
210 |
215 |
220 |
σ (1/cm. Ω) |
1262 |
1197 |
1136 |
1080 |
1028 |
980 |
935 |
893 |
κ= 0.016 (w/cm.°C) |