CuCrSe2: a high performance phonon glass and electron crystal thermoelectric material

Abstract

The efficient conversion of heat into electricity using a thermoelectric approach requires high performance materials with the thermoelectric figure of merit ZT ≥ 1. Here we report on bulk CuCrSe₂, which exhibits a very high ZT ∼ 1 at 773 K. The titled compound exhibits an electrical resistivity of ∼2.8 mΩ cm, a Seebeck coefficient of ∼160 μV K⁻¹, together with very low thermal conductivity ∼7 mW cm⁻¹ K⁻¹ at 773 K. The very low thermal conductivity of bulk CuCrSe₂ is attributed to phonon scattering by various sources such as (i) superionic Cu ions between the CrSe₂ layers, (ii) nanoscale precipitates in the bulk and (iii) natural grain boundaries due to the layered structure of the material. This unusual combination of thermoelectric properties for CuCrSe₂ suggests that it is an ideal example of the phonon glass and electron crystal approach.