WP1: Development of thermoelectric intrinsically conducting polymers and carbon-based nanocomposites

This work package is focused on the preparation of new generations of organic and carbon-based thermoelectric materials for evidencing the critical phenomena and the relation structure/properties which allow enhancing the thermoelectric figure-of-merit ZT. Extensive studies of the influence of doping, synthesis routes and chemical composition of soft maters on the properties of charges, phonon transport and on the intrinsic properties of the semiconductors are achieved.

The main objectives of WP1 are:

  • the synthesis of new intrinsically-conductive polymer (ICP) nano-composites doped with conductive nanofillers for increasing and optimizing the charge transport properties without increasing the thermal conductivity,
  • the preparation of new ICP nanocomposites doped with ceramic and organic nanofillers for decreasing the thermal conductivity without decreasing the charge transport,
  • the study of the influence of the doping on the Seebeck coefficient in organic semiconductors and reaching coefficients up to 200 μVK-1,
  • and the development of new carbon nanostructures with improved chemical compositions and bulk structure for enhancing the charge transports and the phonon confinements.

WP2: Synthesis if nanostructured inorganic & hybrid materials

In the second work package our interest is the production of improved inorganic materials for thermo-electric (TE) applications. We also aim at developping an organic/inorganic hybrid material for high and intermediate temperature applications.

WP2's objectives are:

  • the design and fabrication of inorganic semiconductor-based nanostructures such as superlattices (SLs), nanowires (NWs) and quantum dots (QDs) with the explicit purpose of exploiting the reduced dimensionality to enhance TE power,
  • the development of novel nanostructured oxide TE materials with low thermal but improved electrical conductivity,
  • the preparation of rationally-selected phononic crystals embedded in different TE media for active phonon filtering,
  • and the selection of most promising materials for combination in novel inorganic/organic hybrid thermoelectrics with improved TE properties.

WP3: Materials characterization

The research in WP3 aims at developing a thorough understanding of the influence of the micro-, nanostructure, surfaces and/or interfaces and dimensionality in the energy flow across the various materials obtained in WP1 and WP2 to provide reliable feedback to material researcher in WP1 and WP3, and to theoreticians in WP4, in order to fully understand the mechanism of heat and electron transport.

The different tasks of WP3 consist in:

  • the comparison of the various techniques available within the consortium through round-robin experiments,
  • the structural characterization of the materials produced in WP1 and WP2 thanks to a wide variety of techniques (XRD, AFm, SEM, TEM, RBS, ...),
  • and the characterization of the materials thermal, electrical and thermophysical properties by different techniques (3 ω method, SNOM, Raman, time resolved THz spectroscopy...).

WP4: Theory and modelling

The different parameters entering in the figure of merit are the Seebeck coefficient S, the phonon and electron thermal conductivities κL and κe, respectively, and the electronic conductivity σ. In this workpackage we analyze the influence of material composition, interface resistance, roughness, size, dimensions or external fields on these parameters in order to optimize the figure-of-merit of a particular system. We use structural parameters obtained in WP3 to input the various models and the thermophysical data to compare with the experiments and benchmark the calculations.

The objectives of WP4 can be summarized as follows:

  • extend and develop theoretical models and methods suitable to the materials and nanostructures studied in nanoTHERM,
  • identify in the developed models the crucial parameters minimizing the thermal conduction and maximizing the electrical conductivity to optimize the thermo-electric figure-of-merit ZT,
  • to feed WP1 and WP2 in order to optimize the developed nanomaterials and nanostructures.

WP5: Proof of concept of thermoelectric modules involving developed materials

In WP5, the new and most promising materials investigated in WP1 and WP2 are used to explore their suitability for a thermoelectric application. The proof of concept is focused in cooling applications and waste heat recovery from heat sources transforming this into electrical current.

The work is focused on:

  • the search for a suitable bonding solution for new interface materials including mechanical stability, electrical and thermal conductance of and the diffusion pressure bonding,
  • the test of the electrical properties of the including resistivity measurements and Seebeck voltage as well as life test,
  • and the exploration of a new module structure including its design and lay-out configuration, considering flexible or ceramic basic modules.