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Nano-layered thin films of quaternary bismuth telluride lead selenide for low-dimensional thermopile devices

Objective

Efforts are made to harness cheap, inexhaustible, eco-friendly renewable sources of energy. Among them, thermoelectric (TE) conversion is a promising source of non-conventional energy. A wide range of materials has been tested for TE purposes. Application of non-conventional semiconductors in TE power generators, cooling units and thermostats, IR detectors etc. stimulate search for superior materials. Bismuth chalcogenide alloys represent suitable candidates for these applications. The essential material parameter, the TE figure of merit, depends on the material's Seebeck coefficient, electrical conductivity and thermal conductivity.

The main aim of TE materials research is to improve the figure of merit, which essentially depends on the nature of carrier and phonon scattering in the material. Thus the theoretical target of the proposal is to investigate qualitatively the nature of carrier scattering in bismuth telluride / lead selenide quaternary alloys and to estimate the extent of non-lattice scattering contributions contained. To improve the figure of merit by reducing the thermal conductivity, elements with higher atomic weight will be selected to be involved in chalcogenide compounds. Starting from the synthesis of bulk and thin film material, experimental work will optimise the figure of merit of deposited layered thin films ending up to development of device technology for thermopiles.

Effects of low-dimensional transports related to nano-size layered intermittent films will be exploited as a powerful tool to further reduce the thermal conductivity. Characterization of thin films will be accomplished by XRD, SEAD (structure), TEM, SEM (morphology), EDAX (analysis). Having achieved single phase purity and target composition of the films, Seebeck coefficient, electrical resistivity, and thermal conductivity will be measured in dependence on temperature for optimisation of the figure of merit. Finally, the performance of thin film thermopiles will be tested.

Call for proposal

FP6-2004-MOBILITY-7
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Coordinator

DEUTSCHES ZENTRUM FÜR LUFT- UND RAUMFAHRT E.V. [GERMAN AEROSPACE CENTER (DLR)]
Address

Köln
Germany