Efficient Photothermoelectric Conversion in Lateral Topological Insulator Heterojunctions

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Nanostructuring thermoelectric materials improves their figure of merit by tuning electron and phonon transport.
• Three-dimensional topological insulators, like bismuth chalcogenides, are promising for enhanced thermoelectric performance due to topologically protected surface states.
• Previous studies focused on individual bismuth chalcogenide nanostructures' photothermoelectric properties, leaving nanostructured p-n junctions unexplored.

Discussion:

• This study experimentally investigates the room temperature thermoelectric conversion of lateral heterostructures formed by n-type Bi2Te2Se and p-type Sb2Te3.
• Scanning photocurrent microscopy reveals efficient thermoelectric conversion at the p-n heterojunction by utilizing hot carriers of opposite signs.
• The extracted Seebeck coefficient difference (ΔS = 200 μV/K) aligns with bulk material values and DFT calculations.

Key Insights:

• Demonstrated efficient room-temperature thermoelectric conversion in nanostructured lateral heterostructures of topological insulators.
• Quantified a Seebeck coefficient difference of 200 μV/K, validating the potential of these materials.
• Exploited hot carrier effects at the p-n junction for enhanced thermoelectric performance.

Outlook:

• Potential for developing advanced thermoelectric devices utilizing nanostructured topological insulators.
• Further research into optimizing doping levels and heterostructure design for improved efficiency.
• Exploration of other bismuth chalcogenide combinations for thermoelectric applications.