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Item type:Publication, Access status: with files , Metamaterial emitter for thermophotovoltaics stable up to 1400 °CHigh temperature stable selective emitters can significantly increase efficiency and radiative power in thermophotovoltaic (TPV) systems. However, optical properties of structured emitters reported so far degrade at temperatures approaching 1200 °C due to various degradation mechanisms. We have realized a 1D structured emitter based on a sputtered W-HfO 2 layered metamaterial and demonstrated desired band edge spectral properties at 1400 °C. To the best of our knowledge the temperature of 1400 °C is the highest reported for a structured emitter, so far. The spatial confinement and absence of edges stabilizes the W-HfO 2 multilayer system to temperatures unprecedented for other nanoscaled W-structures. Only when this confinement is broken W starts to show the well-known self-diffusion behavior transforming to spherical shaped W-islands. We further show that the oxidation of W by atmospheric oxygen could be prevented by reducing the vacuum pressure below 10 −5 mbar. When oxidation is mitigated we observe that the 20 nm spatially confined W films survive temperatures up to 1400 °C. The demonstrated thermal stability is limited by grain growth in HfO 2 , which leads to a rupture of the W-layers, thus, to a degradation of the multilayer system at 1450 °C.Publicationtype: Journal ArticleScopus© Citations 77 434 366 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , High Temperature Optical MetamaterialsWe investigate spectrally selective high temperature stable metamaterial emitters for thermophotovoltaics. We demonstrate band-edge emitters based on a W-Hf02 multilayer metamaterial stable up to 1400°C. Conditions for improved selectivity and thermal stability are discussed.Publicationtype: Conference Paper18