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Unusual n-type thermoelectric properties of Bi2Te3 doped with divalent alkali earth metals

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Title: Unusual n-type thermoelectric properties of Bi2Te3 doped with divalent alkali earth metals

Author(s): Sejin Byun; Joonil Cha; Zhou C.; Yong Kyu Lee; Hyungseok Lee; Park S.H.; Lee W.B.; In Chung

Subject: Alkaline earth metal doping, ; Bismuth telluride, ; n-type conduction, ; Thermoelectric, ; Waste heat

Abstract: Bi2Te3-based materials are a representative thermoelectric system operating near ambient temperature. Their n-type family is very limited and underperforms the p-type counterpart, which is a major concern in the thermoelectric community. Here we report that alkali earth metals (AE = Mg, Ca, Sr, Ba) in Group 2 unusually induce n-type thermoelectric properties in Bi2Te3. Mg is the most efficient electron donor among them. The x = 0.01 sample of MgxBi2-xTe3 (x = 0.005, 0.01, 0.015) system exhibits remarkably enhanced power factor and ZT of ~0.8 at 350 K in comparison with pristine Bi2Te3. The improved performance is attributed to simultaneously enhanced electrical conductivity and reduced lattice thermal conductivity. Remarkably, MgxBi2-xTe3 materials show larger Seebeck coefficients than those expected by the theoretical Pisarenko relation. C. 2018 Elsevier Inc