Near-field radiative heat transfer between multilayer structures composed of different hyperbolic materials

Near-field radiative heat transfer (NFRHT) has drawn significant interest in the recent years, including thermal management and energy harvesting. The NFRHT between single hyperbolic materials (HMs) has been thoroughly investigated. However, the research on the NFRHT between periodic multilayer struc-tures composed of different HMs is rarely discussed. Moreover, the coupling effect of hyperbolic phonon polaritons (HPPs) supported by different HMs is still unclear. In this work, we investigated the NFRHT between multilayer structures composed of hexagonal boron nitride (hBN) and alpha-phase molybdenum tri-oxide (alpha-MoO3), separated by vacuum layers. The influence of the gap distance, the unit-cell number, the thickness of the HMs and thickness of the vacuum layer on the NFRHT are discussed. The numerical results show that the maximal total heat flux (THF) between six-cell multilayer structures is 19 times compared to the THF between hBN films at the gap distance of 50 nm and is 1.46 times compared to the THF between alpha-MoO3 films at the gap distance of 30 nm. Such enhancement can also be found at other similar gap distances. The vacuum layer promotes the coupling of HPPs supported by different HMs, which can be elucidated by the energy transmission coefficients. This work could benefit the application of near-field thermal radiative devices based on HMs. (c) 2023 Elsevier Ltd. All rights reserved.