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Interfacial State Modulation toward High-Performance n-Type Bi2Te2.7Se0.3 Thermoelectric Material
Qiujun Hu1, Yanhe Qian1, He Zhou1
1School of Materials Science and Engineering, Henan University of Technology, Zhengzhou 450001, China.
ACS Applied Materials & Interfaces
|August 22, 2025
Summary
Interfacial engineering of 2D MoS2 nanosheets in bismuth telluride selenide thermoelectrics enhances performance by scattering phonons and boosting charge transport. This approach significantly improves the figure of merit (ZT) for advanced thermoelectric applications.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Nanotechnology
Background:
- Optimizing n-type Bi2Te2.7Se0.3 (BTS) thermoelectrics requires strategies to reduce thermal conductivity and increase charge carrier mobility.
- Two-dimensional (2D) nanoarchitectures offer potential for phonon scattering and charge transport enhancement.
Purpose of the Study:
- To achieve dual phonon-charge regulation in BTS thermoelectrics through interfacial engineering of van der Waals-integrated MoS2 nanosheets.
- To investigate the impact of MoS2 integration on thermoelectric properties, including electrical conductivity, Seebeck coefficient, and thermal conductivity.
Main Methods:
- Epitaxial growth of MoS2 nanosheets at BTS grain boundaries with c-axis alignment.
- Density functional theory (DFT) calculations to analyze Fermi level alignment and energy barriers.
- Thermal transport measurements to assess phonon scattering and bipolar conduction suppression.
- Carrier mobility and electrical conductivity measurements.
Main Results:
- Periodic heterojunctions formed by MoS2 nanosheets selectively scatter phonons while preserving electrical conductivity.
- DFT revealed asymmetric energy barriers enhancing the Seebeck coefficient via Fermi level alignment.
- Interfacial charge redistribution suppressed bipolar conduction, and carrier mobility increased by ~1.5 times.
- Achieved a figure of merit (ZT) of 1.32 at 425 K, with an average ZT (ZT_ave) of 1.23 from 300-500 K.
- Assembled modules demonstrated a maximum power output (Pmax) of 0.74 W and efficiency (η) of 6% at ΔT = 150 K.
Conclusions:
- Interfacial engineering of 2D MoS2 nanosheets provides an effective strategy for dual phonon-charge regulation in BTS thermoelectrics.
- This approach decouples electron-phonon interdependence, leading to significantly enhanced thermoelectric performance.
- The study establishes 2D nanoarchitectonics as a promising paradigm for next-generation thermoelectric materials and devices.
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