Thermoelectric property studies on CuxBi2SeS2 with nano-scale precipitates Bi2S3

Abstract The microscopic mechanisms for higher thermoelectric performance of cost competitive rock salt compound Bi 2 SeS 2 were investigated. A low doping of Cu as an n-type dopant was conducted in order to optimize the band structure and improve the electrical conductivity. It was revealed that this compound exhibits a Seebeck coefficient higher than 300 μV K −1 , which sustains above 100 μV K −1 even with Cu doping, leading to a higher power factor. The microstructural characterizations revealed nano-scale Bi 2 S 3 precipitates in the Cu x Bi 2 SeS 2 matrix, beneficial to the lower lattice thermal conductivity that is insensitive to the Cu doping. A thermoelectric figure-of-merit factor ZT of ~0.7 at 450 °C in accompanying with the power factor of ~5.36 μW cm −1  K −2 was obtained under the optimized doping level, enabling this environmentally friendly compound interesting for thermoelectric power generation applications.