Doping, Alloying, or Compositing? How Copper Introduction Pathways Dictate Thermoelectric Performance in GeTe
Yang Li1, Yunpu Zhang1, Yuting Zhang1
1School of Materials Science and Engineering, Shanghai University, 99 Shangda Road, Shanghai 200444, China.
ACS Applied Materials & Interfaces
|June 15, 2026
Summary
Investigating copper introduction methods in germanium telluride (GeTe) reveals that compositing with BaCu2Te2 significantly enhances thermoelectric performance (zT > 2.0). The pathway impacts carrier concentration, mobility, and thermal conductivity for optimized thermoelectric materials.
Area of Science:
- Materials Science
- Solid State Physics
- Nanotechnology
Background:
- Germanium telluride (GeTe) exhibits promising thermoelectric properties but suffers from high carrier concentrations.
- Optimizing GeTe performance requires careful control over doping and microstructure.
- Copper (Cu) is an effective dopant, but its introduction method significantly influences material properties.
Purpose of the Study:
- To systematically compare the effects of three different copper (Cu) introduction routes on the thermoelectric performance of a Ge0.95Bi0.05Te matrix.
- To elucidate the distinct mechanisms by which direct doping, alloying, and compositing with BaCu2Te2 influence carrier concentration, mobility, and thermal conductivity.
- To identify the optimal strategy for enhancing the dimensionless thermoelectric figure of merit (zT) in GeTe-based materials.
Main Methods:
- Synthesis and characterization of Ge0.95Bi0.05Te samples with Cu introduced via direct doping, BaCu2Te2 alloying, and BaCu2Te2 compositing.
- Systematic analysis of electrical conductivity, Seebeck coefficient, and thermal conductivity as a function of temperature for each introduction route.
- Evaluation of carrier concentration, carrier mobility, and density-of-states effective mass to understand performance variations.
Main Results:
- All three Cu introduction methods reduced hole concentration, increasing the Seebeck coefficient but decreasing electrical conductivity.
- Direct Cu doping optimized carrier mobility but showed moderate zT (∼1.86) due to limited phonon scattering.
- The Ge0.95Bi0.05Te + 2.0 wt % BaCu2Te2 composite achieved a peak zT exceeding 2.0 at 623 K due to enhanced carrier scattering and reduced lattice thermal conductivity.
Conclusions:
- The pathway of Cu introduction critically governs the thermoelectric performance of GeTe by balancing carrier modulation, mobility, effective mass, and phonon scattering.
- Compositing with BaCu2Te2 offers a superior strategy for enhancing GeTe thermoelectric properties compared to direct doping or alloying.
- This study provides a framework for synergistically combining doping and secondary-phase engineering in GeTe-based thermoelectric materials.
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