High thermoelectric properties realized in earth-abundant Bi2S3 bulk via carrier modulation and multi-nano-precipitates synergy

Abstract Bi2S3 with earth abundant elements has been considered as a potential thermoelectric material. However, it is challenging to make Bi2S3 materials as a promising high-performance thermoelectric device due to its poor electrical transport properties and the coupling between its electrical and thermal transport properties. In this work, we present a new strategy that can significantly improve electrical transport properties, as well as reduce the lattice thermal conductivity by carrier modulation and introducing multi-nano-precipitates in PbBr2 doped Bi2S3 bulk samples. The electrical conductivity of Bi2S3 was boosted more than one order magnitude higher than that of pristine Bi2S3 after the introducing of Pb and Br, which is demonstrated as the replacement form at the sites of Bi and S, respectively. The resultant Bi2S3 shows an enhanced high power factor of 690 μWm-1K-1 at 598 K, three times higher than that in pristine samples. Besides, the lattice thermal conductivity was reduced to 0.35 Wm-1K-1 at 673 K due to multi-nano-precipitates synergy, i.e., Bi2(S1-xBrx)3 and (Bi1-yPby)2S3 nanoprecipitates in the Bi2S3 matrix. A high ZT of ~0.8 was therefore achieved at 673 K for Bi2S3 with 1.5 mol% PbBr2, a record value in the state-of-the-art Bi2S3 system.