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The Thermoelectric Properties of Bismuth Telluride

Bismuth telluride is the working material for most Peltier cooling devices and thermoelectric generators. Bi2Te3 (or, more precisely, its alloys with Sb2Te3 for p-type and Bi2Se3 for n-type material) has the highest thermoelectric figure of merit, zT, of any material around room temperature. Since thermoelectric technology will be greatly enhanced by improving Bi2Te3 or finding a superior material, this review aims to identify and quantify the key material properties that make Bi2Te3 such a good thermoelectric. The large zT can be traced to the high band degeneracy, low effective mass, high carrier mobility, and relatively low lattice thermal conductivity, contributing to its remarkably high thermoelectric quality factor. Using literature data augmented with newer results, these material parameters are quantified, giving clear insight into the tailoring of the electronic band structure of Bi2Te3 by alloying or reducing thermal conductivity by nanostructuring. For example, this analysis clearly shows that the minority carrier excitation across the small bandgap significantly limits the thermoelectric performance of Bi2Te3, even at room temperature, showing that larger bandgap alloys are needed for higher temperature operation. Such effective material parameters can also be used for benchmarking future improvements in Bi2Te3 or new replacement materials. The n-type Bi2Te3-xSex alloy lags behind its p-type counterpart in thermoelectric performance and does not lend itself as readily to simple transport modeling, which complicates engineering. Combining literature data with recent results across the entire alloy composition range, the complex electronic structure dynamics and trends in lattice thermal conductivity are explored. Spin-orbit interaction is critical in determining the position and degeneration of the various conduction band minima. This behavior is incorporated into a two-band effective mass model to estimate the transport parameters in each band. An alloy scattering model demonstrates how phonon scattering behaves differently on either side of the intermediate-ordered compound Bi2Te2Se due to chalcogen site occupancy preference. The parameterization of the electronic and thermal transports presented can be used in future optimization efforts. If you are looking for high quality, high purity, and cost-effective Bismuth Telluride, or if you require the latest price of Bismuth Telluride, please feel free to email contact mis-asia.

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