Valence Disproportionation of GeS in the PbS Matrix Forms Pb5Ge5S12 Inclusions with Conduction Band Alignment Leading to High n-Type Thermoelectric Performance
Journal Article
·
· Journal of the American Chemical Society
- Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou, Fujian (China); Fuzhou Univ. (China); Nanyang Technological Univ. (Singapore); Northwestern Univ., Evanston, IL (United States); Northwestern University
- Northwestern Univ., Evanston, IL (United States)
- Univ. of Michigan, Ann Arbor, MI (United States)
- Nanyang Technological Univ. (Singapore); Northwestern Univ., Evanston, IL (United States); Huazhong Univ. of Science and Technology, Wuhan (China)
- Fuzhou Univ. (China)
- Agency for Science, Technology and Research (A*STAR) (Singapore). Institute of Materials Research and Engineering
- Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou, Fujian (China); Nanjing Univ. (China)
- Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou, Fujian (China); Fuzhou Univ. (China)
- Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou, Fujian (China); Fuzhou Univ. (China); Nanjing Univ. (China)
- Nanyang Technological Univ. (Singapore)
Converting waste heat into useful electricity using solid-state thermoelectrics has a potential for enormous global energy savings. Lead chalcogenides are among the most prominent thermoelectric materials, whose performance decreases with an increase in chalcogen amounts (e.g., PbTe>PbSe>PbS). Herein, we demonstrate the simultaneous optimization of the electrical and thermal transport properties of PbS-based compounds by alloying with GeS. The addition of GeS triggers a complex cascade of beneficial events as follows: Ge2+ substitution in Pb2+ and discordant off-center behavior; formation of Pb5Ge5S12 as stable second phase inclusions through valence disproportionation of Ge2+ to Ge0 and Ge4+. PbS and Pb5Ge5S12 exhibit good conduction band energy alignment that preserves the high electron mobility; the formation of Pb5Ge5S12 increases the electron carrier concentration by introducing S vacancies. Sb doping as the electron donor produces a large power factor and low lattice thermal conductivity (κlat) of ~0.61 Wm-1K-1. The highest performance was obtained for the 14% GeS-alloyed samples, which exhibited an increased room temperature electron mobility of ~121 cm2V-1s-1 for 3 × 1019 cm-3 carrier density, and a ZT, of 1.32 at 923 K. This is ~ 55% greater that the corresponding Sb-doped PbS sample and is one of the highest reported for the n-type PbS system. Moreover, the average ZT (ZTavg) of ~0.76 from 400 to 923 K is the highest for PbS-based systems.
- Research Organization:
- Northwestern Univ., Evanston, IL (United States)
- Sponsoring Organization:
- National Natural Science Foundation of China; National Science Foundation (NSF); USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- SC0014520
- OSTI ID:
- 1867609
- Journal Information:
- Journal of the American Chemical Society, Journal Name: Journal of the American Chemical Society Journal Issue: 16 Vol. 144; ISSN 0002-7863
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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