ELECTRON & PHONON TRANSPORT IN FUNCTIONAL MATERIALS

THERMOELECTRICITY

has attracted considerable attention as a future green energy source because of its capability to convert heat into practical electric energy. However, its commercialization has been hindered by the low conversion efficiency of thermoelectric materials. To increase the conversion efficiency, a material should exhibit high electrical conductivities with low thermal conductivities. To achieve the apparently unphysical requirement, a proper understanding of electron and phonon transport must be accompanied. My research is focused on revealing an underlying mechanism of improved performance in state-of-the-art thermoelectric materials, as well as finding novel applications of thermoelectric phenomena in other materials systems.

Phase boundary effect in AgBiSnSe3

It is demonstrated that the principal hole-killer defect in AgBiSe2-based thermoelectric materials is Bi-on-Ag antisite, which dispels conventional belief where Se vacancies might be responsible for n-type conductivity

Twisting in tellurium crystal

Elemental Te has a helical chain structure which can show twisting morphology on bulk scale. It is demonstrated that electron transport is well preserved while phonon transport is suppressed to obtain high thermoelectric properties.

Discovery of thermoelectrobiocatalysis

The main disadvantage of utilizing thermoelectric generators in waste heat recovery is a poor conversion efficiency of heat into electrical energy. It is demonstrated that the thermal energy can be directly converted into chemical energy via a combination of thermoelectric materials with biocatalysts.