Excellent thermoelectric performance induced by interface effect in MoS₂/MoSe₂ van der Waals heterostructure

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Thermoelectric materials convert waste heat into electricity, but their efficiency is often limited.
• Molybdenum disulfide (MoS₂) and molybdenum diselenide (MoSe₂) are 2D materials with potential thermoelectric applications.
• Engineering heterostructures offers a route to enhance thermoelectric properties.

Purpose of the Study:

• To investigate the thermoelectric properties of MoS₂/MoSe₂ lateral and van der Waals heterostructures.
• To explore strategies for improving the thermoelectric performance of 2D materials.
• To understand the underlying mechanisms responsible for enhanced thermoelectricity in these heterostructures.

Main Methods:

• Density functional theory (DFT) calculations were employed to model the material structures.
• Non-equilibrium Green's function (NEGF) method was used to simulate electron and phonon transport.
• Analysis of thermal conductance and power factor to evaluate thermoelectric performance.

Main Results:

• MoS₂/MoSe₂ lateral heterostructures show improved thermoelectric performance compared to pure MoS₂ due to reduced thermal conductance.
• MoS₂/MoSe₂ van der Waals heterostructures exhibit significantly enhanced thermoelectric performance, reaching a room temperature ZT of 3.5.
• The enhanced performance in van der Waals heterostructures is attributed to strongly localized electron and phonon states, leading to ultralow thermal conductance.
• Thermoelectric performance in MoS₂/MoSe₂ van der Waals heterostructures is insensitive to contact area variations.

Conclusions:

• Constructing MoS₂/MoSe₂ van der Waals heterostructures is an effective strategy to significantly boost thermoelectric performance.
• The findings highlight the potential of 2D heterostructures for efficient thermoelectric energy conversion.
• The presented approach can be extended to other 2D materials for diverse applications.