High efficiency Al-N cermet solar coatings with double cermet layer film structures

Zhang, Qi-Chu

doi:10.1088/0022-3727/32/15/324

Cited by 35 publications

(27 citation statements)

References 24 publications

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“…A main challenge is making a solar absorber that can both absorb broadband solar radiation and suppress re-radiation at high temperature. This challenge can be analytically expressed by the following figure of merit, called the thermal transfer efficiency [8]:…”

Section: Selective Solar Absorbermentioning

confidence: 99%

“…Among the listed selective absorbers, metaldielectric composites and semiconductor-metal tandems have similar thermal conversion efficiencies at temperatures higher than 700 K [8,31]. One-dimensional aperiodic multilayer PhCs follow closely behind, but have more complex structures [32].…”

Section: Selective Solar Absorbermentioning

confidence: 99%

“…A cermet consists of nanoscale metal particles embedded within ceramic binders [30]. Typical ceramic binder materials include alumina (Al 2 O 3 ) [41], silicon dioxide (SiO 2 ), aluminum oxynitride (AlON) [8] and zirconium dioxide (ZrO 2 ) [42]. The cermet layer by itself has strong solar absorption and high transmission in the mid-IR.…”

Section: Metal-dielectric Composite Selective Solar Absorbersmentioning

confidence: 99%

“…A single layer of graded Ni/Al 2 O 3 on stainless steel was reported to have an averaged solar absorptance of 94%, and an averaged thermal emittance of only 7% at 773 K [31]. It is also proposed that for Al sp -AlON (Al sputtered in AlON binder) cermet solar absorber, a tenlayer graded cermet can be simplified as a double-layer cermet, yielding 86% thermal transfer efficiency at 1 sun illumination and a temperature of 353 K [8]. Another type of cermet structure uses porous alumina as the ceramic binder.…”

Section: Metal-dielectric Composite Selective Solar Absorbersmentioning

confidence: 99%

“…In accordance with the modular design of a STPV system, such as the one shown in Figure 2 [6], the system conversion efficiency can be broken down as a product of three component efficiencies [7]: where ηo is the concentration efficiency, governed by the concentrating optics, η t is the thermal transfer efficiency of light into usable heat [8] and η tpv is the TPV efficiency of converting heat to electricity. However, it is important to note that these three nominally independent terms still interact within the same system, and thus have many linkages, such as temperature, energy flux, and environmental conditions.…”

Section: Introductionmentioning

confidence: 99%

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Solar thermophotovoltaics: reshaping the solar spectrum

et al. 2016

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Abstract:Recently, there has been increasing interest in utilizing solar thermophotovoltaics (STPV) to convert sunlight into electricity, given their potential to exceed the Shockley-Queisser limit. Encouragingly, there have also been several recent demonstrations of improved systemlevel efficiency as high as 6.2%. In this work, we review prior work in the field, with particular emphasis on the role of several key principles in their experimental operation, performance, and reliability. In particular, for the problem of designing selective solar absorbers, we consider the trade-off between solar absorption and thermal losses, particularly radiative and convective mechanisms. For the selective thermal emitters, we consider the tradeoff between emission at critical wavelengths and parasitic losses. Then for the thermophotovoltaic (TPV) diodes, we consider the trade-off between increasing the potential short-circuit current, and maintaining a reasonable opencircuit voltage. This treatment parallels the historic development of the field, but also connects early insights with recent developments in adjacent fields. With these various components connecting in multiple ways, a system-level end-to-end modeling approach is necessary for a comprehensive understanding and appropriate improvement of STPV systems. This approach will ultimately allow researchers to design STPV systems capable of exceeding recently demonstrated efficiency values.

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Section: Selective Solar Absorbermentioning

confidence: 99%

Section: Selective Solar Absorbermentioning

confidence: 99%

Section: Metal-dielectric Composite Selective Solar Absorbersmentioning

confidence: 99%

Section: Metal-dielectric Composite Selective Solar Absorbersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Solar thermophotovoltaics: reshaping the solar spectrum

et al. 2016

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Metallic Photonic Crystal Absorber‐Emitter for Efficient Spectral Control in High‐Temperature Solar Thermophotovoltaics

Rinnerbauer

Lenert

Bierman

et al. 2014

Advanced Energy Materials

250

202

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thermochemical, and solar thermophotovoltaics. There exist a range of solutions with high absorptivity for low and intermediate temperatures. [1][2][3] However, for many applications, high operating temperatures (>700 K) are advantageous to achieve higher system effi ciencies. Conventional absorbers are unsuitable at these high operating temperatures since there are more considerations to be taken into account. [ 4 ] Firstly, the materials and structures need to be thermally stable and to maintain their optical properties at these high temperatures. Refractory metals are most advantageous due to their high melting point and low vapor pressure. Secondly, it is crucial that the absorber exhibits spectrally selective absorptance; namely high absorptivity in the shorter wavelength range to absorb most of the solar spectrum and low absorptivity (i.e., emissivity) in the longer wavelength range to minimize losses due to re-emission. Furthermore, this selectivity, i.e., the spectral range of high and low absorptivity, has to be tailored for the specifi c system operating conditions to achieve maximum system effi ciency.It is therefore advantageous to use PhCs which offer the possibility to tailor the spectral absorptance [ 5,6 ] and thus optimize system effi ciency. Several absorbers based on 1D multilayer stacks, [ 7,8 ] 2.5D structures such as pyramids, [9][10][11] 3D PhCs in refractory metals, [ 12,13 ] as well as metamaterials [14][15][16] have been proposed. Here, we demonstrate the suitability of a 2D PhC comprising a square lattice of cylindrical cavities etched into a Ta substrate as a highly effi cient and selective absorber at high temperatures, i.e., above 1000 K. While all of the above approaches achieve good spectral selectivity, the 2D PhC design is a compact and thermally robust structure, minimizing the number of interfaces as compared to multilayer or 3D PhC approaches which is crucial for high temperature stability. At the same time, fabrication is simple and scalable and can be achieved by standard semiconductor processes. In this 2D PhC design, the absorptivity of the material is selectively enhanced by the introduction of cavity modes and the spectral range of enhancement, i.e., high absorptivity, can be tuned A high-temperature stable solar absorber based on a metallic 2D photonic crystal (PhC) with high and tunable spectral selectivity is demonstrated and optimized for a range of operating temperatures and irradiances. In particular, a PhC absorber with solar absorptance α α = = 0.86 and thermal emittance ε ε = 0.26 at 1000 K, using high-temperature material properties, is achieved resulting in a thermal transfer effi ciency more than 50% higher than that of a blackbody absorber. Furthermore, an integrated double-sided 2D PhC absorber/ emitter pair is demonstrated for a high-performance solar thermophotovoltaic (STPV) system. The 2D PhC absorber/emitter is fabricated on a double-side polished tantalum substrate, characterized, and tested in an experimental STPV setup along with a fl at Ta absorber...

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