Research Areas

imageBand Structure Engineering of PbTe based alloys for Thermoelectrics

High valley degeneracy is just one of the peculiar features of PbTe based materials that makes them the most efficient thermoelectric materials for waste heat recovery. Alloying can finely tune the band structure to enhance thermoelectric performance as well as control doping and reduce thermal conductivity.




imageComplex Zintl Compounds and Phase Boundary Mapping

The complex crystal structures of Zintl Phases lead to low phonon velocity and diffuson dominated low thermal conductivity while the chemistry of Zintl phases facilitates strategies for tuning the electronic transport. Phase Boundary Mapping is often needed to explore the full range of properties.






Transport Models in Complex Materials - Semiconducting Polymers

Electrical Transport Semiconducting Polymers have many properties that can be described using generalized transport models. Sometimes a transport function similar to that used in crystalline semiconductors fits well despite the structural complexity and inhomogeneity in organic and polymer semiconductors. Effects of localization can also be included.


Half Heusler Thermoelectric Materials

Many Half Heusler compunds are semiconductors despite their seemingly intermetallic constituants. This can be rationalized using Zintl chemistry, to show that Half Heusler thermoelectris are based on valence balenced semicondutors. These Zintl chemistry principels can be used then to understand p- and n-type doping as well as defects such as the role of Nb-vacancies in Nb0.8+xCoSb. It also explains that interstitial Ni easily forms in (Ti,Zr)Ni1+xSn adding filled electronic states in the band gap.



Skutterudites, based on CoSb₃, are the new thermoelectric materials most developed to supplant Bi₂Te₃ and PbTe based materials in space and commercial applications. Their complex electronic and atomic structures gives them ideal eletrical and thermal properties for thermeoelectrics


Cu2SeLiquid Like Thermoelectric Materials

Some thermoelectric materials contain fast-diffusing, even 'super-ionic' atoms within a crystalline sublattice of another type of atom. This extraordinary 'liquid-like' behaviour results in an intrinsically low lattice thermal conductivity which enables high zT in an otherwise simple semiconductor.


imageThermoelectric Nanomaterials

Interfaces at the nanometer scale can be used to scatter long mean-free-path phonons to reduce the phonon or lattice thermal conductivity and increase zT.