Performance of α‑, β- and γ‑GeSe Monolayers for Near-Field Radiative Heat Transfer: An Ab Initio Study.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Two-dimensional (2D) materials like Germanium Selenide (GeSe) are promising for near-field radiative heat transfer (NFRHT).
• Three polymorphs (α, β, γ) of monolayer GeSe exist, with potential for NFRHT applications.
• Previous studies investigated α and β phases separately, lacking a direct comparison of all three.

Purpose of the Study:

• To systematically compare the NFRHT performance of α, β, and γ phases of monolayer GeSe.
• To investigate the influence of optical conductivity and electron effective mass on NFRHT.
• To determine if highly anisotropic materials offer superior heat transfer compared to less anisotropic ones.

Main Methods:

• Density Functional Theory (DFT) calculations for physical parameters.
• Calculation of effective electron masses and optical conductivities for each phase.
• Simulations assuming n-doped monolayers to enhance heat flux for NFRHT.

Main Results:

• All three GeSe polymorphs (α, β, γ) exhibit comparable maximum heat fluxes for NFRHT.
• Optical conductivities varied significantly, from isotropic to highly anisotropic, across the phases.
• The results challenge the expectation that high anisotropy directly correlates with enhanced NFRHT.

Conclusions:

• Monolayer GeSe polymorphs offer similar NFRHT performance despite differing optical properties.
• Material properties beyond optical anisotropy, such as hyperbolic plasmon-polaritons, are crucial for optimizing NFRHT.
• This research highlights the complexity of NFRHT and the need for a holistic approach to material selection.