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[摘要]：The abundance of low-temperature waste heat necessitates the development of reliable and scalable thermal-to-electric energy conversion technology. The thermoelectric device is one viable option. Commercially available Bi2Te3-based materials are optimized for near room temperature cooling applications. Currently there are no mass-produced materials available for 400 K to 650 K thermoelectric power generation. We report the successful realization of high performance n-type Bi-2(Te1-xSex)(3)-based materials for the temperature range of interest, using a commercial zone-melting technique. The introduction of Se effectively increases the band gap, which significantly suppresses the "turn-over" in Seebeck coefficient and the appearance of a pronounced bipolar effect, shifting the corresponding temperature of the optimum thermoelectric figure of merit ZT towards a higher temperature range. Furthermore, we demonstrate that the electron concentration of Bi-2(Te0.5Se0.5)(3) can be effectively adjusted by iodine doping. The samples with electron concentrations between 3 x 10(19) and 4.5 x 10(19) cm(-3) display optimal thermoelectric performances. The highest ZT value reaches 0.86 at 600 K for the sample with the electron concentration of 4.0 x 10(19) cm(-3), whose average ZT between 400 K and 640 K is 0.8, making this scalable zone-melted low-Te content Bi-2(Te0.5Se0.5)(3) compound a promising candidate for low-temperature power generation. |
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