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Enhanced Thermoelectric Performance of p-Type Sb/Ag Co-Doped Bi2Te2Se and n-Type W/Cl Co-Doped Bi2Te2.7Se0.3 and Module Configuration Optimization
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DOI：10.1021/acsaem.6c01069.png)
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Abstract
En 中文
This study reaffirmed the high effectiveness of co-doping strategies in enhancing the figure of merit zT of both p- and n-type Bi2Te3-based materials. Sb/Ag and W/Cl co-doping simultaneously optimized the carrier concentration and suppressed the lattice thermal conductivity in p-type Bi2Te2Se and n-type Bi2Te2.7Se0.3, respectively. The effectiveness of Sb/Ag and W/Cl co-doping was supported by the density of states obtained from first-principles electronic structure calculations using, for each co-doped composition, a single large supercell containing all relevant dopants. Moreover, it was demonstrated that the thermoelectric properties of Bi2Te3-based systems were highly sensitive to synthesis conditions. For example, the sign of the Seebeck coefficient of the samples prepared in this study was opposite to that reported previously. A zT of ∼0.94 at 400 K was obtained for p-type BiSb0.95Ag0.05Te2Se, while a zT of ∼0.92 at 325 K was obtained for n-type Bi1.9995W0.0005Te2.697Se0.3Cl0.003. The p-type BiSb0.95Ag0.05Te2Se and the n-type Bi1.9995W0.0005Te2.697Se0.3Cl0.003, both possessing high power factors and high zT values, exhibited slightly different electrical and thermal transport properties (ρnκp/ρpκn∼0.8, where ρ and κ represent the electrical resistivity and thermal conductivity of respective materials). However, the finite element simulation confirmed that a module composed of these materials exhibited high output power and high conversion efficiency, even when the p- and n-type legs were designed with identical geometries, such as cross-sectional area and height.
Keywords:
thermoelectrics
bismuth telluride
first-principles electronic structure calculation
co-doping strategies
module configuration
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5.5
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1.1W
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4.5W
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