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초록

Te-free Bi2S3-based thermoelectric (TE) materials present compelling prospects for ecofriendly and industrial scale-up applications, owing to their earth-abundant constituents, cost-effectiveness, and intrinsic nontoxicity. However, their low figure of merit (ZT) restricts their practical applications. In this study, both experiments and density functional theory calculations reveal that donor-acceptor PbCl2 can simultaneously improve its electrical and thermal properties. In Bi2S3, Cl acts as the donor while Pb serves as the acceptor, and their competitive relationship leads to a trade-off between sigma and S, thus increasing the power factor. Dense nanoscale structures (nanodomains) with the same structure but different light and dark paths, derived from the chemical composition fluctuation, are embedded in the PbCl2-incorporated Bi2S3 matrix. Such a special structure leads to a low kappa(lat) of similar to 0.33 W m(-1) K-1 in the Bi2S3-1.5% PbCl2 sample. As a result, a rather high ZT value of similar to 0.82 at 673 K and an average ZT of 0.46 at 323-673 K are obtained for the PbCl2-incorporated Bi2S3 sample, resulting in the superior TE performance of Bi2S3-based bulks. This work provides an effective strategy for enhancing TE properties in Bi2S3 semiconductors by nanodomain engineering.

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