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Layered Sn- and Ge-based monochalcogenides have been known as promising semiconductor materials with appropriately narrow band gaps, close to those of Si and GaAs. On the other hand, Pb-based ones possess much narrower band gaps and adopt the cubic rock-salt (RS) type structure under ambient conditions, and their layered structures are considered to be thermodynamically unstable. Here, we have successfully stabilized the GeS-type layered structure in lightly Sn-doped PbS by combination of high-temperature solid-state reaction with thermal quenching. It is experimentally confirmed that an equilibrium phase of the layered GeS-type Sn-rich (Pb1-xSnx)S with x > 0.6 is a p-type semiconductor. However, we have clarified that the stabilized nonequilibrium layered phase with 0.2 ≤ x ≤ 0.5 is a n-type semiconductor with band gap of 1.18–1.22 eV. Furthermore, the layered nonequilibrium phase exhibits an ultra-low room-temperature thermal conductivity of 0.40–0.65 W/(mK), much lower than those of both end members; i.e., the GeS-type SnS (x = 1) and the RS-type PbS (x = 0). Based on the first-principles electron and phonon transport calculations, the layered n-type (Pb0.75Sn0.25)S potentially shows a high thermoelectric figure-of-merit of 0.34 even at 300 K under an optimized electron concentration. The controllability of ambipolar carrier polarity in the layered (Pb1-xSnx)S alongside the low thermal conductivity is an advantageous characteristic for applications based on p-n homojunctions such as photovoltaics and thermoelectrics.

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  This document is the Accepted Manuscript version of a Published Work that appeared in final form in Nonequilibrium Layered PbS Stabilized by Sn Doping: Bipolar Semiconductors with Low Thermal Conductivity, copyright © 2024 American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see  https://doi.org/10.1021/acsaelm.4c01572

Keyword: Thermal conductivity, chalcogenide, nonequilibrium synthesis, carrier doping, carrier transport property, thermoelectric property

Date published: 2024-11-26

Publisher: American Chemical Society (ACS)

Journal:

• ACS Applied Electronic Materials (ISSN: 26376113) vol. 6 issue. 11 p. 8339-8350

Funding:

• Ministry of Education, Culture, Sports, Science and Technology JPMXP1122683430
• Japan Society for the Promotion of Science 24H00376
• Japan Society for the Promotion of Science JP20H00302
• Japan Society for the Promotion of Science JP21H04612
• Japan Society for the Promotion of Science JP22H01766
• Japan Society for the Promotion of Science JP24K21671
• Japan Society for the Promotion of Science JP22H04964

Manuscript type: Author's version (Accepted manuscript)

MDR DOI: https://doi.org/10.48505/nims.5111

First published URL: https://doi.org/10.1021/acsaelm.4c01572

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Updated at: 2025-11-08 08:30:28 +0900

Published on MDR: 2025-11-08 08:21:13 +0900