SnSe: The rise of the ultrahigh thermoelectric performance material

Thermoelectric materials can generate electric power from dissipating heat without releasing any undesirable chemicals. They thus can increase global energy efficiency and reduce the use of fossil fuels that are a major resource for generating electric energy, thereby concurrently addressing energy and environmental crises seriously threatening humanity. Increasing a thermoelectric figure of merit, ZT, of materials has been a prime goal in thermoelectrics because an efficiency of thermoelectric power generation has been low until very recently. The recent development of ultrahigh thermoelectric performance in polycrystalline SnSe-based materials is one of the most prominent breakthroughs in the history of thermoelectrics. They show an exceptionally high ZT of ~3.1 at 783 K and average ZT of ~2.0 from 400 to 783 K, which are the highest for any bulk thermoelectric systems. Here we review the recent advances in SnSe thermoelectrics, greatly changing the paradigm of studies and applications of thermoelectric technology.