Activated lone-pair electrons lead to low lattice thermal conductivity: a case study of boron arsenide

Due to the ability of firsthand solid-state conversion to electrical power from thermal energy, thermoelectrics have attracted a lot of attention for the valuable applications in reusing waste resources and thus may make crucial contributions to the crisis of environment and severe energy problems. Reducing the thermal conductivity is an efficient way to boost the thermoelectric performance. In this talk, I would like to introduce an effective way to realize low thermal conductivity by introducing lone-pair electrons or making the lone-pair electrons stereochemically active through bond nanodesigning. With proper bond nanodesigning, the intrinsic thermal conductivity of BAs is largely lowered, which thus would benefit its applications in thermoelectrics with further nanostructuring. Fundamental insight is gained for the underlying mechanism of the reduction of thermal conductivity. Similar approach can also extended to other semiconductor systems, such as silicon and gallium nitride. The approach for realizing low thermal conductivity and the underlying mechanism uncovered in this talk would largely benefit the design of thermoelectric devices with improved performance, especially in future researches involving novel materials for energy applications.