Dual-boost thermoelectric power generation in a GeTe/Mg3Sb2-based module

Studies on thermoelectric materials have been primarily centred on conversion efficiency, as if to assert a high-efficiency thermoelectric module always generates a large electrical power. However, there is a trade-off between conversion efficiency and power density under thermal and electrical energy losses due to contact resistances at electrode junctions. Thus, simultaneously boosting the power density and conversion efficiency (‘dual-boost’) is essential. Here, to overcome the trade-off by minimizing energy losses, we focus on two approaches for p-type GeTe- and n-type Mg3Sb2-based thermoelectric materials. First approach is to reduce thermal conductivity of GeTe by inducing a strong phonon scattering and tuning the hole concentration. Second approach is to reduce electrical contact resistivities of GeTe and Mg3Sb2 by optimizing highly conductive electrode junctions. As a result, we achieve a record-high dual-boost performance (1.94 W/cm2 and 10.1%) in a practical-size module. The result will advance thermoelectric generator technology for widespread applications.