Multifunctional Molybdenum Doping Boosts PbS Thermoelectrics to Peak ZT 1.2, Significantly Enhancing Conversion Efficiency

August 2, 2026

Advanced Functional Materials International

Overview

In PbS-based thermoelectric materials, low-solubility molybdenum (Mo) doping was shown to form multiple precipitates (MoS2, Sb, Pb), reduce cation vacancies, and promote lattice planarization. This improved carrier mobility, enhancing the average power factor from 11.7 µW cm−1 K−2 to 15.6 µW cm−1 K−2. Further selenium (Se) alloying led to Pb0.965Sb0.015Mo0.02S0.8Se0.2 achieving a peak ZT value of 1.2 at 923 K, significantly improving thermoelectric conversion performance.

In Depth

Key Findings: Multifunctional Molybdenum Doping Achieves Peak ZT of 1.2 in PbS Thermoelectric Materials

Research published in Advanced Functional Materials reveals that molybdenum (Mo) doping dramatically enhances the thermoelectric conversion performance of lead sulfide (PbS)-based materials. Specifically, even with low solubility, Mo undergoes diverse chemical reactions within the PbS matrix, forming multiple precipitates (MoS2, Sb, Pb). This optimization of the material’s electrical and thermal properties results in an impressive peak ZT value of 1.2 at 923 K, marking a significant improvement in conversion efficiency compared to conventional materials.

Technical and Experimental Details

Multifunctionality of Molybdenum: Despite its low solubility in PbS, Mo forms fine precipitates of MoS2, Sb, and Pb within the grain boundaries and matrix. These precipitates act as phonon scattering centers, effectively reducing lattice thermal conductivity.
Cation Vacancy Reduction and Enhanced Carrier Mobility: Mo doping demonstrably reduces the concentration of cation vacancies (defects at Pb sites) in PbS. This suppresses carrier scattering, leading to improved carrier mobility of free electrons. Consequently, the material’s electrical conductivity is boosted, and the average power factor significantly enhances from the previous 11.7 µW cm−1 K−2 to 15.6 µW cm−1 K−2.
Promotion of Lattice Planarization: Mo doping is also shown to promote planarization within the PbS crystal lattice, which contributes to the formation of efficient carrier transport pathways and further enhances mobility.
Optimization through Selenium Alloying: Further optimization was achieved through alloying with selenium (Se). The composition Pb0.965Sb0.015Mo0.02S0.8Se0.2 achieved a peak ZT value of 1.2 at a relatively moderate temperature of 923 K (approximately 650 °C). A ZT value exceeding 1.0 is considered critically important for practical thermoelectric applications, indicating high conversion efficiency.

Background and Industry Context

Thermoelectric materials, capable of directly converting thermal energy into electrical energy and vice-versa, are gaining attention for applications in waste heat recovery, solid-state cooling, and power generation. Broad applications are anticipated, including automotive exhaust heat utilization, industrial waste heat recovery, and self-powered IoT devices. However, discovering materials with high conversion efficiency (ZT values) has been a significant challenge in materials science due due to the need to simultaneously optimize conflicting properties: electrical and thermal conductivity. PbS-based materials, being relatively inexpensive and stable, have been promising candidates, but their performance improvement faced limitations.

Future Outlook and Commercial Significance

This performance enhancement in PbS-based thermoelectric materials through Mo doping holds the potential to significantly improve the efficiency of waste heat recovery systems and solid-state cooling devices. The achieved ZT value of 1.2 is particularly crucial for paving the way towards commercial applications. This research suggests that by leveraging the multifunctionality of low-solubility dopants like Mo, it is possible to overcome the limitations of conventional thermoelectric material design and develop higher-performance, cost-effective materials. In the future, it is expected that this technology will accelerate the development of highly efficient thermoelectric generation modules and devices adaptable to various temperature ranges, driving advancements in sustainable energy solutions.

Source: https://api.semanticscholar.org/CorpusID:290549203

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