Conduction type control and power factor enhancement of the thermoelectric material Al2Fe3Si3

Control of the conduction type of a target thermoelectric material is necessary to fabricate power generation modules. When developing thermoelectric modules for practical usage, the cost and toxicity of constituent p- and n-type thermoelectric materials should be lowered and minimized. The Al2Fe3Si3 intermetallic compound with a relatively low thermal conductivity of ∼6 W/m-K at 300 K is promising for use in low-cost and non-toxic thermoelectric devices. Al2Fe3Si3 possesses a wide composition range of Al and Si concentration with a constant Fe content. Fine tuning of the Al/Si content of Al2Fe3Si3 allowed its conduction type to be controlled and power factor to be enhanced. We found that Al2Fe3Si3 displayed thermoelectric behavior in the relatively low-temperature region below 500 K, which is attractive for its future practical usage. We produced Al2Fe3Si3 materials with high power factors of 730 μW/mK2 for n-type and 430 μW/mK2 for p-type at 373 K, which might be useful in sensor applications at such a temperature.