Two-dimensional bilayer phosphorenes: a tunable platform for nanoscale heat energy transfer

Active control of heat energy transfer as the key factor in thermal management at nanoscale, has recently attracted increasing attention. Relying on intrinsic in-plane anisotropy and tunable electronic and optical properties, the monolayer of black phosphorus called phosphorene, has exhibited great potential in near-field radiative heat transfer (NFRHT). The results show that the imaginary part of optical conductivity is enhanced one-order of magnitude as electron density increases from n=5 × 1012 /cm2 to n=20 × 1012/cm2. Herein, the dynamic control of NFRHT is analyzed in the bilayer phosphorene system. We studied the tunable NFRHT between two phosphorene layers under different doping concentrations, realizing NFRHT is dominant in lower doping levels. For the energy of 0.05 eV, when the doping concentration decays a quarter, the phosphorene sheet would be extended toward a high-k wavevector over 2 times. Moreover, it is found that decreasing the vacuum gap between the bilayer can result in the dramatic increase of the NFRHT rate. This work can open up a new way to utilize anisotropic two-dimentional materials for dynamic management of heat energy transfer at the nanoscale.