Reverse Non-Equilibrium Molecular Dynamics Demonstrate That Surface Passivation Controls Thermal Transport at...

Area of Science:

• Materials Science
• Nanotechnology
• Thermal Physics

Background:

• Interfacial thermal transport is critical in semiconductor nanomaterials due to small dimensions.
• Understanding surface effects is key to controlling heat flow at these interfaces.

Purpose of the Study:

• To investigate the impact of surface structure and passivation on thermal transport at semiconductor/organic interfaces.
• To determine how CdSe slab thickness, crystal facet, and ligand coverage affect interfacial thermal conductance (G).

Main Methods:

• Employed reverse nonequilibrium molecular dynamics simulations.
• Calculated interfacial thermal conductance (G) between hexane solvent and passivated wurtzite CdSe surfaces.
• Analyzed ligand-grafting density, orientational ordering, and solvent penetration.

Main Results:

• Interfacial thermal conductance (G) shows a nonmonotonic dependence on ligand-grafting density, peaking around 0.08 ligands/Ų.
• Surface passivation can increase G by approximately one order of magnitude compared to bare surfaces.
• Crystal facet influences achievable ligand densities and thus G, with variations up to a factor of ~2.

Conclusions:

• A balance of competing effects, including orientational ordering and solvent penetration, governs the nonmonotonic thermal conductance.
• Tailoring surface passivation and crystal facet selection can enable anisotropic heat flow in nanostructures.
• Surface structure and passivation are critical design parameters for managing thermal transport in nanomaterials.