Berlin 2015 – scientific programme
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DS: Fachverband Dünne Schichten
DS 36: Poster Session I
DS 36.84: Poster
Thursday, March 19, 2015, 09:30–12:00, Poster A
Synthesis and thermoelectric properties of Bismuth Sulfide and Bismuth Sulfide Selenide alloys — •Maik Matthiesen, Lewis Akinsinde, Heiko Reith, and Kornelius Nielsch — Institute of Nanostructure and Solid State Physics, Universität Hamburg, Hamburg, Germany
Thermoelectric Generators (TEG) enable the direct conversion of heat into electrical energy. Materials with high thermoelectric figure of merit (ZT=α2σ T / κ) are required for efficient energy conversion. TE materials should be non-toxic, use abundant elements and the synthesis should be simple and scalable. In recent years, a large variety of semiconducting material systems have been investigated in the search for new high performance TE-materials. It has been demonstrated that doping of Bi2S3 and Bi2S3-Bi2Se3 alloys can increase their thermoelectric performance significantly. In this study we have synthesized Bi2S3 and Bi2S3-Bi2Se3 alloys using sealed quarz ampule synthesis. To tune the charge carrier concentration we added slight amounts of dopants. The obtained materials are characterized with regard to their TE properties (electrical/thermal conductivity and Seebeck coefficient: σ,κ and α) on commercial equipment. The chemical composition and crystal structure are also examined. We observed a larger powerfactor (α2σ) in rapidly cooled melts of Chlorine doped Bi2S3 compared to slowly cooled melts. This may be connected with stronger defect doping in the rapidly cooled Ingots. The synthesis method and parameters such as temperature and time need to be taken into account when optimizing such materials.