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Schlagwörter:
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Zusammenfassung:
The superionic conductor Cu2-delta Se has been shown to be a promising
thermoelectric at higher temperatures because of very low lattice
thermal conductivities, attributed to the liquid-like mobility of copper
ions in the superionic phase. In this work, we present the potential of
copper selenide to achieve a high figure of merit at room temperature,
if the intrinsically high hole carrier concentration can be reduced.
Using bromine as a dopant, we show that reducing the charge carrier
concentration in Cu2-delta Se is in fact possible. Furthermore, we
provide profound insight into the complex defect chemistry of bromine
doped Cu2-delta Se via various analytical methods and investigate the
consequential influences on the thermoelectric transport properties.
Here, we show, for the first time, the effect of copper vacancy
formation as compensating defects when moving the Fermi level closer to
the valence band edge. These compensating defects provide an explanation
for the often seen doping inefficiencies in thermoelectrics via defect
chemistry and guide further progress in the development of new
thermoelectric materials.
