Ag, Pb co-doped SnSe high performance thermoelectric materials

Abstract

SnSe, as a novel thermoelectric material, has ultrahigh thermoelectric properties in its single crystals, while the thermoelectric properties of polycrystals need to be further improved. Introducing atomic disorder to increase the lattice anharmonicity of the material is a typical strategy to reduce the lattice thermal conductivity and enhance the thermoelectric properties. Ag and Pb co-doping increased the effective carrier mass of the samples, and the resultant strong phonon scattering leads to a drastic decrease of the lattice thermal conductivity over the whole temperature range, and at the same time, optimizes the energy-band structure of SnSe, which finally significantly increases the Seebeck coefficient of SnSe. However, the electrical properties of SnSe deteriorate due to Pb elemental doping, so we introduce Ag atoms with higher intrinsic conductivity to increase its conductivity. At 800 K, the electrical conductivity of the Sn0.82Ag0.08Pb0.1Se sample is about twice as much as that of the undoped SnSe, and the thermal conductivity is 0.28 W mK−1. The ZT value of Sn0.82Ag0.08Pb0.1Se sample peaked at ∼1.33 at 800 K compared to only ∼0.48 for undoped SnSe. The ZT ave value of Sn0.82Ag0.08Pb0.1Se sample in the temperature range of 300–500 K was ∼0.36 compared to only ∼0.083 for undoped SnSe samples.