Stabilized Cubic GeTe With Matched Grain-Boundary Networks and Band Convergence for High-Performance Dual-Mode...

Area of Science:

• Materials Science
• Solid State Physics
• Thermoelectrics

Background:

• Lead-free GeTe-based thermoelectrics show promise but are hindered by ferroelectric phase transitions and instability.
• Optimizing thermoelectric materials requires balancing electrical transport and thermal conductivity.

Purpose of the Study:

• To develop a strategy for stabilizing the cubic phase of GeTe-based thermoelectrics.
• To enhance both thermoelectric and mechanical properties for dual-mode applications.
• To improve device efficiency for power generation and cooling.

Main Methods:

• AgSbTe2 alloying to suppress ferroelectric transitions.
• Iodine doping to refine domains and tune band structure.
• Cooperative structural-electronic regulation for property optimization.

Main Results:

• Stabilized cubic phase, suppressing ferroelectric transition.
• Achieved a room-temperature zT of ~0.7 and a peak zT of ~2.2 at 773 K.
• Enhanced mechanical integrity with ~248 MPa compressive strength.
• Demonstrated ~11% efficiency in a power-generation device and a max ΔT of ~65.6 K in a cooling device.

Conclusions:

• The proposed strategy enables concurrent phase stabilization and performance enhancement in GeTe-based thermoelectrics.
• Developed a generalizable framework for creating high-reliability, dual-mode thermoelectric devices.
• Optimized materials show superior performance across a wide temperature range.