High performance magnesium-based plastic semiconductors for flexible thermoelectrics.

Area of Science:

• Materials Science
• Solid State Physics
• Energy Harvesting

Background:

• Flexible electronics require low-cost, high-performance thermoelectric materials with superior plasticity at room temperature.
• Conventional thermoelectric semiconductors are brittle, while plastic organic/inorganic materials exhibit inferior thermoelectric performance.
• Existing materials fail to meet the demands for durable and efficient flexible thermoelectric power generation.

Purpose of the Study:

• To develop a novel inorganic polycrystalline thermoelectric material with simultaneous high performance and plasticity.
• To investigate the underlying mechanisms responsible for the enhanced plasticity in magnesium-antimony-bismuth based materials.
• To demonstrate the fabrication and performance of flexible thermoelectric modules using the developed material.

Main Methods:

• Synthesis and characterization of low-cost inorganic polycrystalline Mg3Sb0.5Bi1.498Te0.002.
• Evaluation of thermoelectric properties (figure of merit, zT) and mechanical properties (large strain) at room temperature.
• Analysis of the microstructural origins of plasticity, including dislocation networks and bonding characteristics.
• Fabrication of in-plane and out-of-plane flexible thermoelectric modules.

Main Results:

• Mg3Sb0.5Bi1.498Te0.002 achieved a large strain of ~43% and a high figure of merit zT of ~0.72 at room temperature.
• The material surpasses the performance of brittle Bi2(Te,Se)3 and plastic Ag2(Te,Se,S) and organic thermoelectric materials.
• Optimization of Bi content in Mg3Sb2-xBix (x=0 to 1) enhanced both thermoelectric performance and plasticity.
• Flexible thermoelectric modules fabricated from Mg3Sb2-xBix demonstrated promising power density.

Conclusions:

• The developed Mg3Sb2-xBix material offers a unique combination of high thermoelectric performance and exceptional plasticity.
• The inherent plasticity, attributed to dislocation networks and persistent Mg-Sb/Bi bonds, enables facile processing into flexible devices.
• This work paves the way for advanced flexible electronics and inspires further research into plastic inorganic semiconductors.