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Device-Level ZT Correlation for Validating Single-Leg Efficiency in GeTe Thermoelectrics
Yi-Hsuan Lai1, Cheng-Xiu Liu2, Kuang-Kuo Wang3
1Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan.
Device ZT accurately predicts thermoelectric conversion efficiency, unlike average zT which overestimates performance. This study validates Device ZT using experimental data for GeTe systems, providing a realistic framework for device evaluation.
Area of Science:
- Materials Science
- Energy Conversion
- Solid State Physics
Background:
- The correlation between thermoelectric figure of merit (zT) and conversion efficiency (η) is poorly defined for GeTe systems.
- Conventional zT metrics oversimplify by assuming temperature-independent properties, leading to overestimated device efficiency.
- Device ZT was introduced to evaluate maximum thermoelectric leg efficiency with temperature-dependent properties.
Purpose of the Study:
- To experimentally validate Device ZT as a practical metric for predicting thermoelectric conversion efficiency.
- To establish a direct correlation between material transport properties, Device ZT, and measured device performance.
- To provide a realistic framework for translating material properties into device performance.
Main Methods:
- Calibrated single-leg efficiency measurements.
- Heat-flow analysis.
- Finite-element simulations.
- Experimental validation of Device ZT using CuSb-GeTe legs.
Main Results:
- A CuSb-GeTe leg achieved 5.4% efficiency at ΔT = 400 K.
- Conventional average zT (zTavg) estimates overpredicted performance by nearly twofold.
- Device ZT accurately reproduced the measured device efficiency.
Conclusions:
- Device ZT provides an experimentally validated framework for realistic thermoelectric device performance prediction.
- Device ZT is a practical and reliable metric for evaluating thermoelectric devices, accounting for temperature-dependent properties.
- This work bridges the gap between material-level properties and actual device efficiency in thermoelectrics.
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