Author:
L Wu，X Li，S Wang，T Zhang，J Yang，...
Abstract：
Resonant levels are promising for high-performance single-phase thermoelectric materials. Recently, phase-change materials have attracted much attention for energy conversion applications. As the energetic position of resonant levels could be temperature dependent, searching for dopants in phase-change materials, which can introduce resonant levels in both low and high temperature phases, remains challenging. In this study, possible distortions of the electronic density of states due to group IIIA elements (Ga, In, Tl) in GeTe are theoretically investigated. Resonant levels induced by indium dopants in both rhombohedral and cubic phase GeTe have been demonstrated. The experimental Seebeck coefficients of InxGe1 − xTe exhibit a large enhancement compared with those observed for other prior dopants. Indium dopants reduce the defect concentrations in GeTe, and thus, they lower the carrier concentrations and suppress the electronic component of the total thermal conductivity. The enhanced Seebeck coefficient, together with the suppressed thermal conductivity, leads to a reasonably high ZT of 1.3 at a temperature near 355 °C in In0.02Ge0.98Te. The corresponding average ZT is enhanced by ~ 70% across the entire temperature range of the rhombohedral and cubic phases. These observations indicate that indium-doped GeTe is a promising base material for achieving an even higher thermoelectric performance.
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