Quantitative measurements of transverse thermoelectric generation and cooling performances in SmCo$_5$/Bi$_{0.2}$Sb$_{1.8}$Te$_3$-based artificially tilted multilayer module

Abstract

The transverse thermoelectric generation and cooling performances in a thermopile module composed of recently developed SmCo$_5$/Bi$_{0.2}$Sb$_{1.8}$Te$_3$ artificially tilted multilayers are evaluated quantitatively. When a large temperature difference of 405 $^\circ$C is applied to the SmCo$_5$/Bi$_{0.2}$Sb$_{1.8}$Te$_3$-based module, the open-circuit voltage and output power reach 0.51 V and 0.80 W, respectively. The corresponding maximum power density is 0.16 W/cm$^2$, even if the power is normalized by the device area including areas that do not contribute to the power generation, such as epoxy resin, electrodes, and insulating layers. The maximum energy conversion efficiency for our module in this condition is experimentally determined to be 0.92%. Under the cooling operation, the same module exhibits the maximum temperature difference of 9.0 $^\circ$C and heat flow at the cold side of 1.6 W. Although these values are lower than the ideal thermoelectric performance expected from the material parameters due to the imperfections associated with modularization, the systematic investigations reported here clarify a potential of the SmCo$_5$/Bi$_{0.2}$Sb$_{1.8}$Te$_3$ artificially tilted multilayers as thermoelectric generators and cooling devices.