Temperature-Adaptive Carrier Regulation and Enhanced Thermoelectric Performance in n-Type PbTe via Deep-Shallow...

Area of Science:

• Materials Science
• Solid State Physics
• Thermoelectric Energy Conversion

Background:

• Maximizing the power factor in n-type lead telluride (PbTe) necessitates optimizing carrier concentration across a wide temperature range.
• Conventional shallow donors in PbTe result in a temperature-invariant electron concentration, deviating from optimal levels at higher temperatures.

Purpose of the Study:

• To implement a dynamic deep-shallow co-doping strategy in PbTe to achieve optimal carrier concentration and enhance thermoelectric performance.
• To investigate the combined effects of iodine (shallow donor) and gallium (deep-level donor) on the electronic and thermal transport properties of PbTe.

Main Methods:

• Co-doping PbTe with iodine (shallow donor) and gallium (deep-level donor) to create dynamic carrier concentration.
• Thermal ionization of gallium-related deep impurity states at elevated temperatures to increase electron concentration.
• Optimized synthesis to maintain high carrier mobility and suppress lattice thermal conductivity.

Main Results:

• Achieved a peak power factor of 30 μW·cm^-1·K^-2 for Ga_0.02Pb_0.98Te_0.996I_0.004 due to temperature-dependent carrier optimization and preserved mobility.
• Attained a maximum figure of merit (ZT) of 1.41 at 803 K and an average ZT of 1.00 (400-773 K) for Ga_0.02Pb_0.97Te_0.996I_0.004.
• Demonstrated a 25% improvement in ZT compared to iodine-only doped PbTe.

Conclusions:

• Deep-shallow co-doping is an effective strategy for dynamic carrier engineering in thermoelectrics.
• This approach significantly enhances the thermoelectric performance of n-type PbTe by optimizing carrier concentration and maintaining high mobility.
• The findings present a broadly applicable paradigm for optimizing thermoelectric materials.