#### Description

The role of thermal conductivity in the performance of thermoelectric (TE) devices as compared to other material properties such as Seebeck coefficient and the electrical conductivity will be discussed. A TE energy conversion system that includes thermal contacts for the hot side and the cold side with finite heat transfer performances is considered. Some of the trends in electronics cooling applications have been described. In this article, the effect of material properties as a function of energy current flow direction will be focused.

TEs have an advantage as solid-state heat energy conversion devices especially for applications with spatial constraints. A commonly accepted application is the Peltier cooling of high power or high heat flux electronic devices such as laser diodes (>1 W/mm^{2}). These applications lead to a limited heat transfer performance in both hot and cold contacts. Based on a generic one-dimensional model for TE systems, thermal conductivity appeared to be the most important property to be improved to get better energy conversion performance among three TE properties including Seebeck coefficient and electrical conductivity.

For TE cooling, thermal conductivity of the TE material is the most cost sensitive in terms of mass use of the material, for minimizing the power consumption to pump the heat from the target device at the constrained temperature. Typically in electronics, the device temperature is constrained, such as 65oC–85oC. Hence the maximum cooling to reach minimum target temperature is not always required. Achieving this target temperature with minimum electrical power input for a given power dissipation from the target device is required. The difference in impact between thermal conductivity and the other material properties is on the thermal resistance of the TE element similarly to the energy harvesting system case. By changing any properties, a coefficient-of-performance (COP) of cooling yields the same as ZT remains the same.

This article will summarize the role of thermal conductivity as the thermal resistance match with finite external contacts in the TE microcooler, while relating the effects of the thermal conductivity, Seebeck coefficient, and electrical conductivity to the finite thermal resistance of the TE microcooler.

#### Keywords

thermoelectric, microcooler, interface, contact, coefficient of performance, cost, figure-of-merit (ZT), optimization

#### DOI

10.5703/1288284315547

Role of Thermal Conductivity for Thermoelectrics with Finite Contacts

The role of thermal conductivity in the performance of thermoelectric (TE) devices as compared to other material properties such as Seebeck coefficient and the electrical conductivity will be discussed. A TE energy conversion system that includes thermal contacts for the hot side and the cold side with finite heat transfer performances is considered. Some of the trends in electronics cooling applications have been described. In this article, the effect of material properties as a function of energy current flow direction will be focused.

TEs have an advantage as solid-state heat energy conversion devices especially for applications with spatial constraints. A commonly accepted application is the Peltier cooling of high power or high heat flux electronic devices such as laser diodes (>1 W/mm^{2}). These applications lead to a limited heat transfer performance in both hot and cold contacts. Based on a generic one-dimensional model for TE systems, thermal conductivity appeared to be the most important property to be improved to get better energy conversion performance among three TE properties including Seebeck coefficient and electrical conductivity.

For TE cooling, thermal conductivity of the TE material is the most cost sensitive in terms of mass use of the material, for minimizing the power consumption to pump the heat from the target device at the constrained temperature. Typically in electronics, the device temperature is constrained, such as 65oC–85oC. Hence the maximum cooling to reach minimum target temperature is not always required. Achieving this target temperature with minimum electrical power input for a given power dissipation from the target device is required. The difference in impact between thermal conductivity and the other material properties is on the thermal resistance of the TE element similarly to the energy harvesting system case. By changing any properties, a coefficient-of-performance (COP) of cooling yields the same as ZT remains the same.

This article will summarize the role of thermal conductivity as the thermal resistance match with finite external contacts in the TE microcooler, while relating the effects of the thermal conductivity, Seebeck coefficient, and electrical conductivity to the finite thermal resistance of the TE microcooler.