Metamaterial-based integrated plasmonic absorber/emitter for solar thermo-photovoltaic systems

Wu, Chihhui; Neuner, Burton; John, Jeremy; Milder, A.; Zollars, Byron G.; Savoy, Steve; Shvets, Gennady

doi:10.1088/2040-8978/14/2/024005

Cited by 366 publications

(243 citation statements)

References 26 publications

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“…Here we experimentally demonstrate a visibly transparent thermal blackbody, based on a silica photonic crystal, using a thermophotonic approach (17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30). When placed on a silicon absorber under sunlight, such a blackbody preserves and even slightly enhances sunlight absorption, but reduces the temperature of the silicon absorber by as much as 13°C due to radiative cooling.…”

mentioning

confidence: 98%

Radiative cooling of solar absorbers using a visibly transparent photonic crystal thermal blackbody

Zhu

Raman

Fan

2015

Proc. Natl. Acad. Sci. U.S.A.

515

351

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A solar absorber, under the sun, is heated up by sunlight. In many applications, including solar cells and outdoor structures, the absorption of sunlight is intrinsic for either operational or aesthetic considerations, but the resulting heating is undesirable. Because a solar absorber by necessity faces the sky, it also naturally has radiative access to the coldness of the universe. Therefore, in these applications it would be very attractive to directly use the sky as a heat sink while preserving solar absorption properties. Here we experimentally demonstrate a visibly transparent thermal blackbody, based on a silica photonic crystal. When placed on a silicon absorber under sunlight, such a blackbody preserves or even slightly enhances sunlight absorption, but reduces the temperature of the underlying silicon absorber by as much as 13°C due to radiative cooling. Our work shows that the concept of radiative cooling can be used in combination with the utilization of sunlight, enabling new technological capabilities.radiative cooling | thermal radiation | photonic crystal | solar absorber T he universe, at a temperature of 3 K, represents a significant renewable thermodynamic resource: it is the ultimate heat sink. Over midinfrared wavelengths, in particular between 8 and 13 μm, Earth's atmosphere is remarkably transparent to electromagnetic radiation. This wavelength range coincides with the peak wavelength of thermal radiation from terrestrial structures at typical ambient temperatures. Thus, a sky-facing terrestrial object can have radiative access to the universe. Exploiting this radiative access has led to the demonstration of radiative cooling (1-7), as well as proposals for direct electric power generation from thermal radiation of terrestrial objects (8).Whereas historically radiative cooling was largely developed for night-time applications (1-6, 9-13), recent works have achieved daytime radiative cooling (7,14). In particular, it was shown that the radiative cooling to below ambient air temperature can be achieved (7), with a photonic structure that reflects almost all incident sunlight and simultaneously emits significant thermal radiation in the midinfrared. Such a structure, being a near-perfect solar reflector, makes no use of incident sunlight. On the other hand, in many applications, including solar cells (15) and outdoor structures (16), the utilization of sunlight through absorption is intrinsic for either operational or aesthetic considerations, but the heating associated with sunlight absorption is undesirable. For these applications, lowering operating temperatures via radiative cooling is only viable if one can simultaneously preserve the absorption of sunlight.Here we experimentally demonstrate a visibly transparent thermal blackbody, based on a silica photonic crystal, using a thermophotonic approach (17-30). When placed on a silicon absorber under sunlight, such a blackbody preserves and even slightly enhances sunlight absorption, but reduces the temperature of the silicon absorber by as m...

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mentioning

confidence: 98%

Radiative cooling of solar absorbers using a visibly transparent photonic crystal thermal blackbody

Zhu

Raman

Fan

2015

Proc. Natl. Acad. Sci. U.S.A.

515

351

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“…[1][2][3][4][5][6][7] By selectively absorbing solar energy while suppressing long wavelength emission, optimal solar-thermal energy conversion can be achieved. In practical STPV systems, selective absorbers must simultaneously contain optical, manufacturing, and reliability properties.…”

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confidence: 99%

Enabling Ideal Selective Solar Absorption with 2D Metallic Dielectric Photonic Crystals

Chou¹,

Yeng²,

Lee³

et al. 2014

Advanced Materials

126

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The selective absorption of sunlight plays a critical role in solar-thermophotovoltaic (STPV) energy conversion by tailoring both the absorption and emission spectrums for efficient solar-thermal-electrical energy conversion. [1][2][3][4][5][6][7] By selectively absorbing solar energy while suppressing long wavelength emission, optimal solar-thermal energy conversion can be achieved. In practical STPV systems, selective absorbers must simultaneously contain optical, manufacturing, and reliability properties. Previous efforts have typically focused only on a subset of these requirements. In this communication, we present our solution which contains all of the ideal properties of a selective absorber for large-scale and efficient solar energy conversion.The effective absorption of solar energy requires selective absorption across the solar spectrum, high temperature reliability, omnidirectional absorption, and wafer-scale fabrication 2 for mass scalability. Recent developments of metal based selective absorbers have demonstrated 1D, 2D, and 3D metallic photonic crystal structures capable of tailoring the absorption spectrum. [2,[8][9][10][11][12][13][14] One dimensional metal dielectric stacks have demonstrated promising solar absorbing properties but are unstable at temperatures greater than approximately 600°C. [13] In particular, two-dimensional metallic air photonic crystals (MAPhC) have been shown to selectively absorb light in the near-IR via cavity modes and withstand high temperatures greater than 1000°C; however, the acceptance angle is limited to ±30°, and the absorption in the visible spectrum is limited due to diffraction. [2,11,15] Metamaterial and plasmonic based absorbers have demonstrated wide angle absorption due to their subwavelength periodic structures; however high temperature stability and wafer-scalefabrication have yet to be shown. [1,3,[16][17][18][19] Here we present our 2D metallic dielectric photonic crystal (MDPhC) structure, which simultaneously demonstrates broadband (visible to near-IR) absorption, omnidirectional absorption, wafer-scale fabrication, and high temperature robustness.[20] The wafer-scale fabricated MDPhC has a measured absorption of 85% for photon energies and an absorption below 10% for . Angled measurements show existence of the cavity modes for angles up to 70° from normal. Furnace tests at 1000°C for 24 hours show a robust optical performance due to its fully encapsulated design which helps to retain the metal cavity shapes at high temperatures. [21] Finite-difference time-domain (FDTD) and rigorous coupled wave analysis (RCWA) based simulations indicate that the broadband absorption is due to a high density of hybrid cavity and surface plasmon modes overlaped with an anti-reflection coating (ARC).A schematic image of the MDPhC is shown in Figure 1(a) and (b). The MDPhC utilizes cut-off frequencies of cavity modes to tailor the absorption. Since the cut-off frequency is dependent on the geometry of the cavities, the absorption spectrum can be tuned by simply modif...

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“…Later in the paper we show results using the high melting point metal tungsten. Gold is straightforward to deposit in cleanroom facilities thus we are focusing the majority of our results on it in these initial studies as others have done [28]. With the Au backing layer, the total absorbance is now significantly different from the simple thin layer case in air.…”

Section: Resultsmentioning

confidence: 99%

Broadband metasurface absorber for solar thermal applications

Wan

Chen

Cryan

2015

J. Opt.

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In this paper we propose a broadband polarization independent selective absorber for solar thermal applications. It is based on a metal-dielectric-metal metasurface structure, but with an inter-layer of absorbing amorphous carbon rather than a low loss dielectric. Optical absorbance results derived from Finite Difference Time Domain modelling are shown for ultra-thin carbon layers in air and on 200nm of gold for a range of carbon thicknesses. A gold-amorphous carbon-gold trilayer with a top layer consisting of a 1D grating is then optimised in 2D to give a sharp transition from strong absorption up to 2m to strong reflection above 2m resulting in good solar selective performance. The gold was replaced by the high melting point metal tungsten and is shown to have very similar performance to the gold case. 3D simulations then show that the gold based structure performs well as a square periodic array of squares, however there is low absorption around 400nm. A cross based structure is found to increase this absorption without significantly reducing the performance at longer wavelengths.

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Metamaterial-based integrated plasmonic absorber/emitter for solar thermo-photovoltaic systems

Cited by 366 publications

References 26 publications

Radiative cooling of solar absorbers using a visibly transparent photonic crystal thermal blackbody

Radiative cooling of solar absorbers using a visibly transparent photonic crystal thermal blackbody

Enabling Ideal Selective Solar Absorption with 2D Metallic Dielectric Photonic Crystals

Broadband metasurface absorber for solar thermal applications

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