Stable high temperature metamaterial emitters for thermophotovoltaic applications

Abstract

We report a metamaterial design for a thermophotovoltaic (TPV) emitter. TPVs are similar to photovoltaic solar cells, but they convert heat to electricity instead of sunlight. The focus of this paper is on the emitter stage of the TPV system, which converts the heat into a spectral band which is easily absorbable by the TPV photodiode. The proposed structure consists of a platinum metallic element, an alumina dielectric spacer, and platinum grounding plane on a sapphire substrate. This perfect absorber based metamaterial emitter is shown to robustly operate at 600 °C. This temperature is high enough to enable TPV use for many industrial applications.

Heterogeneous metasurface for high temperature selective emission

“…Additionally, it has well matched CTE to Al 2 O 3 from room temperature to 1500 K, 16 decreasing the likelihood of delamination of a Pt/ Al 2 O 3 stack. The geometry is similar to that used in previous demonstrations, 12,14,17 though our final design uses an encapsulation layer and operates in a different design parameter regime. The mechanism for the resonance has been previously described.…”

“…While other metals, such as tungsten, 19 have shown their emissivity above 2 lm increase >30% at 1300 K compared to room temperature (as predicted by a temperature-dependent Drude model 20 ), two recent publications 14,21 measured no quantifiable change in the emissivity of platinum up to 1100 K, indicating that the temperature-dependent Drude model is not adequate for platinum. Until further studies measure platinum's emissivity above 1100 K, we assume that platinum's emissivity is independent of temperature in our model and use the roomtemperature emissivity to calculate the TPV cell efficiency g TPV and the generated power P out .…”

“…9 Numerous geometries for modifying the emission spectrum have been studied, including metal (such as tungsten) photonic crystals, 7,10 inverse opals, 11 and metal-dielectricmetal (MDM) metasurfaces. 8,[12][13][14] While the first two groups have shown promise regarding emissivity and survivability at operating temperatures, questions remain about the ability to scale these geometries beyond laboratory demonstrations. MDM metasurfaces, on the other hand, can easily be fabricated by standard foundry lithography techniques while exhibiting extremely tailorable emission spectra that can be made angle-independent when the layer thicknesses are significantly sub-wavelength.…”

Selective emitters for thermophotovoltaic applications

“…Recently, negative refractive indices have been realized using man‐made structures and have led to research advances in the development of invisibility cloaks , perfect lenses , and other custom dielectrics. The advanced manipulation of electromagnetic radiation with MMs has also led to the development of perfect absorbers and emitters, which have additional applications in photodetector and photovoltaic enhancement .…”

MEMS switchable infrared metamaterial absorber

“…kind of applications demands that the material used for the devices are high temperature stable. [24,25] Refractory materials are been looked into as the potential candidate for absorbers and plasmonics devices to withstand extremely high temperature. [26] The previous report uses Al as a structural layer and hence cannot be used for these applications due to lower melting point and large thermal coefficient mismatch between Al and Al2O3.…”