(Invited) Nano-Length-Scale Inorganic/Organic Hybridization for Thermoelectric Materials
We have recently found that TiS2-based inorganic/organic hybrid superlattices show a reasonable power factor and ultralow thermal conductivity; ZT=0.21~0.28 at 300~373 K in an ambient atmosphere1). It was also found that the polar molecules coexisting with organic cations in the van der Waals gap between TiS2 monolayers have dielectric screening effects to suppress the electrostatic attractive force between organic cations present in the gap and carrier electrons present in the TiS2 monolayers, and hence carrier mobility is enhanced while lattice thermal conductivity is lowered by increasing dielectric constant of polar molecules, which leads to enhanced ZT2). Such hybrid superlattice materials are mechanically flexible, which would be beneficial for a variety of energy-harvesting applications.
Inorganic/organic hybridization should be a promising concept for the future TE materials design. There are an infinite number of combinations of inorganic and organic species. Nano-length-scale hybridization of the known compounds composed of non-rare and non-toxic elements must be cultivated to discover high-ZT materials.
1. C. L. Wan, K. Koumoto et al., Nature Mater. (2015). [DOI:10.1038/nmat4251]
2. C. L. Wan, K. Koumoto et al., submitted.