Thermoelectric property studies on CuxBi2SeS2 with nano-scale precipitates Bi2S3

The microscopic mechanisms for higher thermoelectric performance of cost competitive rock salt compound Bi2SeS2 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 mu V K-1, which sustains above 100 mu V K-1 even with Cu doping, leading to a higher power factor. The microstructural characterizations revealed nano-scale Bi2S3 precipitates in the CuxBi2SeS2 matrix, beneficial to the lower lattice thermal conductivity that is insensitive to the Cu doping. A thermoelectric figure-of-merit factor ZT of similar to 0.7 at 450 degrees C in accompanying with the power factor of 5.36 mu W cm(-1) K-2 was obtained under the optimized doping level, enabling this environmentally friendly compound interesting for thermoelectric power generation applications. (C) 2015 Elsevier Ltd. All rights reserved.