Hybrid Thermoelectric Materials Based on Porous Silicon: Linking Macroscopic Transport Phenomena to Microscopic Structure and Elementary Excitations

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The project objective is to develop and understand novel hybrid thermoelectric materials based on nanostructured silicon and functionalized polymers. In a nutshell, the notoriously bad thermoelectric performance of bulk silicon shall be overcome in hybrid systems consisting of porous silicon as host substrate and conductive polymers like PEDOT as guest molecules. Here the structured host guarantees at least very low thermal conductivity as prerequisite for an excellent thermoelectric material, whereas electrical properties can be favorably tuned by proper selection of the host molecules. We propose to combine a full macroscopic, thermoelectric characterization of synthesized hybrid samples with structural and dynamical studies by means of x-ray and neutron scattering experiments. Goal is a fundamental understanding of how macroscopic quantities like electrical conductivity, thermal conductivity and Seebeck coefficient relate to electronic band structure and phonon dispersion on a microscopic level. It will be comprehensively investigated, how the properties of host and guest relate to the properties of the hybrid systems and how synergy effects might arise. Ideally, this studies pave the route towards novel design strategies for more efficient thermoelectric materials.