Anomalous thermoelectricity in strained Bi2Te3 films

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Bismuth Telluride (Bi2Te3)-based alloys are crucial for thermoelectric devices like coolers and generators.
• Improving the Seebeck coefficient (S) of these materials has primarily focused on structural and compositional modifications.
• Existing methods for enhancing thermoelectric performance are limited.

Purpose of the Study:

• To investigate anomalous thermoelectric behavior in strained Bi2Te3 films.
• To explore a novel method for adjusting the Seebeck coefficient (S) in thermoelectric materials.
• To understand the underlying mechanisms of the observed anomalous thermoelectricity.

Main Methods:

• Fabrication of strained Bi2Te3 thin films.
• Experimental measurement of the Seebeck coefficient (S) under varying temperature gradients.
• Theoretical analysis involving the coupling of thermoelectric and flexoelectric effects.

Main Results:

• Demonstration of anomalous thermoelectricity where the Seebeck coefficient (S) changes upon reversing the temperature gradient direction.
• Identification of stress gradient-induced coupling between thermoelectric and flexoelectric effects as the origin of this anomaly.
• Significant alteration of S values in strained Bi2Te3 films.

Conclusions:

• Flexoelectric polarization, induced by stress gradients, offers a new mechanism to modulate thermoelectric properties.
• This finding opens a new pathway for tuning the Seebeck coefficient (S) in Bi2Te3-based thermoelectric materials.
• Potential for developing advanced thermoelectric devices with enhanced performance through strain engineering.