High performance thermoelectric Tl9BiTe6 with an extremely low thermal conductivity

Tl9BiTe6 exhibits a thermoelectric figure of merit of ZT similar to 1.2 around 500 K, which significantly exceeds the state-of-the-art materials in this temperature range. The extraordinary thermoelectric performance is mainly due to the extremely low thermal conductivity of Tl9SiTe6 [0.39 W/(m . K) at 300 K]. In fact, the minimum lifetime of the phonons has to be taken into account to describe the thermal conductivity data.