Department of Materials Science

Thick does the trick: Ferroelectricity in two-dimensional (GeTe)m(Sb2Te3)n lamellae

The ternary Ge-Sb-Te alloys (GST) are employed as active material in non-volatile phase-change memory devices, which exploit the large difference in both electrical and optical properties between the amorphous and crystalline phases and the possibility to thermally induce a fast and reversible transition between the two phases. Recently, this technology has attracted great attention for the possible exploitation in neuromorphic computing.

Unraveling active sites in the electrocatalysts of the type Fe-Nx-C during pyrolysis

The depletion of fossil fuels and ongoing ecological challenges underscore the pressing need for sustainable and environmentally friendly energy solutions. In this pursuit, fuel cells have become a focal point in current research, primarily due to their exceptional advantages, with the noteworthy aspect being the recognition of hydrogen as a green energy carrier.

Thermoelectricity: Materials and Applications

setup for device measurements

Thermoelectricity is a class of physical phenomena enabling both the conversion of heat into electricity and the extraction of heat (cooling), in both cases without the use of any movable part. As such, thermoelectric generators are suitable, especially when miniaturized, to harvest low-temperature heat and to make it available as electric power (e.g. to distributed sensor networks or to portable devices). Our research activity focuses both on materials and devices for suitable applications.

Silicon thin films

Energy-selective charge carrier scattering was demonstrated to provide a route to enhance power factor of very heavily boron-doped nanocrystalline silicon films, up to the outstanding value of 40 mW/mK2. Research under way is meant to materials stabilization and to the extension of the process to n-type nanocrystalline silicon films.

Silicon nanowires

Due to its high thermal conductivity, single-crystalline silicon is not suitable as such for thermoelectric applications. Nanostructuration offers effective ways to lower its thermal conductivity. Research is focused on the use of Metal-assisted Chemical Etching (MaCE) as a simple way to obtain Si nanowires (SiNWs). The process, along with the possibility of making electrical contacts localized at Si tips, discloses the opportunity of making bulk-like SiNW pads to be embedded into thermoelectric devices, either for cooling or for heat harvesting.

Paired photovoltaic-thermoelectric harvesters

Photovoltaic (PV) cells only convert a fraction of the solar spectrum, releasing a significant amount of energy as heat. Threfore, solar harvesting might be improved through an accurate coupling of PV cells to thermoelectric generators. Further to energy profitability, hybrid harvesters also meet criteria of economic convenience, which is required for pairing to be practically successful. We mostly work on the direct pairing of specially designed Bi2Te3 thermoelectric generators with perovskite-based photovoltaic cells.

Thermoelectricity under non-stationary conditions

Thermoelectric low efficiencies are basically due to the difficulty of decoupling thermal and electrical conductivity in real systems. Nanotechnology has shown innovative ways to reach such a target. Additionally, thermal and electrical conductivities in bulk thermoelectrics may be uncoupled by operating thermoelectric generators in non-steady state mode. We are exploring how feeding time-modulated heat fluxes may enhanced conversion efficiencies at maximum power.

Principal investigator

Prof. Dario Narducci

Research group website

Research Lab

U5 Building, 1st Floor, Room 1032-1034

Facilities

  • Electron beam evaporator (Kenosistec) 
  • Furnace for high-temperature annealing (up to 1000 °C) under controlled atmosphere 
  • Semi-automatic wire bonder (TPT, HB10 model)
  • Thermostatic baths (-20 °C – 80 °C) 
  • Manual lapping systems 
  • Setup for measuring Hall coefficient as a function of temperature (20 K – 350 K) 
  • Setup for measuring Seebeck coefficient in thin films 
  • Setup for measuring current-voltage characteristics in thin films 
  • Vacuum FTIR spectrophotometer (Brucker VERTEX 70v) 
  • Z-meter 

Scintillating nanotubes for the treatment of the Alzheimer disease

Protein misfolding and aggregation are the fundamental causes of many degenerative conditions, including Alzheimer’s and Parkinson’s disease (AD and PD) as well as type II diabetes. Misfolded proteins are usually biologically inactive; however, the dynamic equilibrium between monomeric and oligomeric aggregates may lead to cytotoxic states that induce the degenerative condition. In AD, amyloid-β (Aβ) and tau proteins misfold and form oligomers and fibrils that accumulate in the brain in pathogenic pathways leading to synaptic loss and selective neuronal cell death.

The chip capable of imitating our eye and our brain

A material that behaves like our eyes and remembers like our brain: this is the discovery of a successful team of researchers from the Italian Institute of Technology, Federico II University of Naples and RWTH University of Aache. The team worked on the synthesis of a new organic material that is conductive and sensitive to light which, when appropriately stimulated, imitates the behaviour of the retina but also memory processes in the brain.

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