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The efficiency of thermoelectric devices is determined not only by the quality of the thermoelectric material but also by the geometrical design of the legs and the properties and design of the contacts with the corresponding soldering process. These influences on the performance of a thermoelectric generator are studied by multiphysics finite element modeling. The simulated data are compared with experimental results for modules manufactured from Bi 2 Te 3 compounds with ZT values >0.8. A decrease of the ZT value for the module by a factor of about four can be traced back to the high contact resistance. The thermal losses at the contact interfaces are negligible for these devices.

Thermoelectric device performance is determined by not only the properties of the thermoelectric material but also the geometrical design and thermal matching of the materials. Leg length and contact quality strongly influence thermoelectric generator efficiency. Experimental results for contact properties are compared with the latest performance measurements on modules manufactured from Bi 2 Te 3 compounds. Module performance is related to the obtained contact resistance and thermoelectric material properties. The different influences are studied using thermoelectric multiphysics finite-element modeling of examples where, in addition to the thermoelectric field equations, further effects such as convection and radiation as well as the temperature dependency of the material properties are taken into account. Extensive thermoelectric device modeling is used to understand the experimental findings with respect to contact properties and geometry.

In this paper, we describe a measuring system based on the Van der Pauw principle with four calibrated type S thermocouples. By means of this system, we conducted traceable measurements of the absolute Seebeck coefficients and the electrical conductivity of thermoelectric bulk materials to establish a precise determination of the power factor. The results of a comparative investigation of metallic (ISOTAN® and Nickel) and semiconducting (SiGe) materials in the temperature range of 300 K–1100 K are presented. The good agreement of the Seebeck coefficients and electrical conductivities measured using the system and the data reported from the literature and values of these transport properties premeasured using another measuring system forms the basis for the usage of the system for the further certification of thermoelectric reference materials for the power factor up to 1100 K.

This note describes the construction and engineering of a high precision Harman set-up for metrology of the thermoelectric figure of merit (ZT) of modules and materials based on steady state AC and DC measurements. The Harman technique presented in this article has a resolution of milli-ZT and it does not employ lock-in amplifiers or AC bridges; rather, the technique is developed to avoid typical complications experienced in AC Harman systems. By one-time reference measurements the best operation point for the system is chosen, minimizing the effects of capacitive loads due to AC signals.