Approaching the fundamental limits of heat transfer at the nanoscale: the surprisingly limited role of inverse design

Prashanth Venkataram, Sean Molesky, Weiliang Jin, Alejandro W. Rodriguez

Research output: Contribution to journalConference articlepeer-review


Radiative heat exchanged between bodies at the nanoscale can surpass blackbody limits on thermal radiation by orders of magnitude due to contributions from evanescent electromagnetic fields, which carry no energy to the far-field. Such super-Planckian emission is known to depend strongly on both material and geometric properties. However, the relative importance and interplay of these two facets and their fundamental limitations remain open questions. While guiding principles have thus far assumed utility in the possibility of improvements (beyond planar media) through nanoscale texturing, thus far trial-and-error explorations and large-scale optimization procedures have failed to surpass the performance of ideal (unstructured) metals [1–3]. In this talk, I will present fundamental limits to nearfield radiative heat transfer in resonant media [4]. We will show that at any given wavelength, multiple scattering between proximate bodies severely limits the marginal utility of nanoscale texturing for the purpose of enhancing near-field heat transfer, beyond shifting the resonant response of bulk materials to selective wavelengths. While compact bodies can benefit from stronger material response (larger indices of refraction and smaller losses) up to a size-dependent threshold, leaving room for applications of inverse design to discover optimal geometries, the near-field heat transfer between extended structures is shown to scale very weakly (logarithmically) with increased material response, and to be practically reached by planar materials at the surface polariton condition. The existence of tight bounds for heat transfer has ramifications for the performance of thermophotovoltaics, nanoscale cooling, and other thermal devices operating in the near field [5].

Original languageEnglish (US)
Pages (from-to)699
Number of pages1
JournalInternational Conference on Metamaterials, Photonic Crystals and Plasmonics
StatePublished - 2019
Externally publishedYes
Event10th International Conference on Metamaterials, Photonic Crystals and Plasmonics, META 2019 - Lisbon, Portugal
Duration: Jul 23 2019Jul 26 2019

All Science Journal Classification (ASJC) codes

  • Electrical and Electronic Engineering
  • Materials Science (miscellaneous)
  • Electronic, Optical and Magnetic Materials
  • Materials Chemistry


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