Tuning of the thermoelectric properties of Inx(M)2-xO3-nanoparticles

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The proposed project is focused on the development of a model system for the design of nanoscale thermoelectrics, and the intentional variation of electrical, thermal and thermoelectrical properties as far as possible independently of each other and the evaluation of theapplications in sensor devices. In this second period within the Priority Program: “Nanostructured thermoelectrica”, we extend the developed indium oxide based material basis for nanoparticle and nanocomposite films as thermoelectric materials Nanostructured films, in comparison to the bulk materials, have the advantage of possessing a high concentration of grains and grain boundaries. In a nanostructured semiconductor with intrinsic surface accumulation of carriers, these grain boundaries lower the thermal conductivity but on the other side, increase the electrical conductivity of the material with a positive impact on the thermoelectric properties. These characteristics are intrinsic properties for several indium containing compounds such as InN, InAs, and In2O3. In this project, we propose InxM2-xO3 nanoparticles (M=Zn, Ga, Ni, Ti) to be used as thermoelectric material. The main goal in the second period is to tune the electrical conductivity and the phonon thermal conductivity in nanoparticles by variation of the particle size and systematic manipulation of the particle surface properties. The major instrument will be the adjustment of the Fermi level (work function) and the surface band bending by specific gas adsorption. The reference values will be obtained by in situ photoelectron spectroscopy. Experimental investigations will be supported by further measurements by partners within the SPP as well as by ensemble Monte- Carlo simulations for thermal and electric conductivity. In future, by using optimized nanoparticle films, these effects will be used for self-powered or highly-sensitive Seebeck gas sensor systems.