Abstract
High-temperature stable emitters with spectral selective functionality are an absolute condition for efficient conversion of thermal radiation into electricity using thermophotovoltaic (TPV) systems. Usually, spectral selective emitters are made up of multilayered materials or geometrical structures resulting from complex fabrication processes. Here, we report a spectrally selective emitter based on a single metal layer coating of molybdenum (Mo) over a 3D dielectric pillar geometry. 3D Mo nanopillars are fabricated using large-area and cost-effective hole-mask colloidal lithography. These nanostructures show an absorptivity/emissivity of 95% below the cut-off wavelength of an InGaAsSb PV cell at 2.25 μm, and a sharp decline in absorptivity/emissivity in the near-infrared regions, approaching a low emissivity of 10%. The 3D Mo nanopillars show outstanding thermal/structural stability up to 1473 K for 24 h duration under Ar atmosphere and polarization and angle invariance up to 60° incidence angles. With a low-cost and scalable fabrication method, 3D Mo nanostructures provide tremendous opportunities in TPV and high temperature photonic/plasmonic applications.
Highlights
Spectral selectivity of nanostructures with structural stability at high temperatures is of great importance in various applications in the fields of thermophotovoltaics (TPV), radiative cooling, energyefficient lighting, photodetection and stray-light elimination [1e16]
Nanostructures stable at temperatures higher than 1273 K and allowing of tailoring the thermal emission above the bandgap of the PV cell are essential in attaining high conversion efficiencies in TPV systems, using PV cells, such as InGaAsSb, GaSb, etc
Theoretically TPV systems can provide efficiencies up to 85% [17], the maximum efficiency achieved so far is below 29% [18e21] due to the limited spectral selectivity and thermal stability of the nanostructures
Summary
Spectral selectivity of nanostructures with structural stability at high temperatures is of great importance in various applications in the fields of thermophotovoltaics (TPV), radiative cooling, energyefficient lighting, photodetection and stray-light elimination [1e16]. Arpin et al [27] showed the fabrication of 3D PhCs coated with a protective HfO2 layer for high temperature stability These structures show excellent thermal and spectral stability up to 1273 K for 12 h. We demonstrate thermal stability of novel 3D Mo nanopillars based metamaterial structures, as spectrally selective emitters, fabricated by a large-area and low-cost patterning method (hole-mask colloidal lithography, HCL). A simple design of the 3D Mo structures with ease of scalable and low-cost fabrication method provide potential candidates for the development of high-efficiency TPV systems, and show a route to make thermally stable structures beyond 1473 K using refractory dielectric substrates such as Al2O3, MgO and HfO2
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