Ling Chen
Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002,
People’s Republic of China

Theremoelectric (TE) materials can realize the direct conversion between electricity and thermal energies, and consequently can be used as power generator and cooler. The key limitation of the expansion of the TE material application is their low energy conversion efficiencies. The efficiency of a TE material can be evaluated by figure of merit, ZT = S2σT/κ. A good TE compound requests simultaneously a large Seebeck coefficient (S), a high electrical conductivity (σ), and a low thermal conductivity (κ). Currently, the major strategies to enhance ZT value include doping, nanolization and filming, as well as exploration of TE compound with novel structure type. Our efforts focus on the exploration of novel Sb-, Te-involved compounds. In our studies, we introduce the ionized cations, such as alkali or alkaline earth metal cations, as a structural scissor into Sb-, Te-binary or ternary systems to generate new ternary or quaternary compounds with low lattice thermal conductivities by utilizing the random vibration characteristic of the ionized cations. Subsequently, to modify the as-syntheized ternary or quaternary compounds with suitable dopants not only to further reduce the long-range lattice vibration, but also to adjust the band gaps and the concentrations of carriers so as to obtain better ZT values. Several serials of compounds with novel structure types, including layed antimonides, tellurides; Sb-based type I clathrates; large caged antimonides, and alkali cation embedded tellurides are discovered. The studies of their single crystal structures, electronic structures and thermoelectric properties are reported here.