High solar absorption of a multilayered thin film structure

Li, Xiaofan; Chen, Yue-Rui; Miao, Jian; Zhou, Peng; Zheng, Yuanzhou; Chen, Liang‐Yao; Lee, YoungPak

doi:10.1364/oe.15.001907

Cited by 68 publications

(42 citation statements)

References 7 publications

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“…Replacing Cu with a Mo substrate, the solar absorber was stable up to 450 6 C in air and 800 6 C in vacuum. 86 Other systems such as Al x O y /Pt/Al x O y , 87 SiO 2 /Ti/SiO 2 /Al, 88 AlN/Ti/ AlN, 89 and HfO x /Mo/HfO 2 were also investigated. 90 The colored solar selective coatings in the Ti/AlN multilayer structure were obtained by adjusting the layer number and thickness.…”

Section: Multilayer Absorbersmentioning

confidence: 99%

Metallic nanostructures for light trapping in energy-harvesting devices

et al. 2014

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Solar energy is abundant and environmentally friendly. Light trapping in solar-energy-harvesting devices or structures is of critical importance. This article reviews light trapping with metallic nanostructures for thin film solar cells and selective solar absorbers. The metallic nanostructures can either be used in reducing material thickness and device cost or in improving light absorbance and thereby improving conversion efficiency. The metallic nanostructures can contribute to light trapping by scattering and increasing the path length of light, by generating strong electromagnetic field in the active layer, or by multiple reflections/absorptions. We have also discussed the adverse effect of metallic nanostructures and how to solve these problems and take full advantage of the light-trapping effect. INTRODUCTIONThe conversion of solar energy to electricity or heat might be the ultimate means to help solve the energy crisis when hydrocarbon resources such as coal and other fossil fuels cannot satisfy the energy demand. Solar energy is abundant, ,5000 times our current power consumption.1 The use of solar energy can also reduce the environmental problems caused by the consumption of fossil fuels by reducing dusts, noxious gases and greenhouse gases, as well as the resulting haze, acid rain and global warming. To date, the worldwide installed capacity of solar harvesting devices is ,60 GW in electric energy and ,300 GW in thermal energy, 2 with an annual rapid increase. For the existing technology, there is room for further improvement by either enhancing the light absorption or avoiding loss of electricity or heat after absorption. Recently, new advances in nanotechnology and material fabrication methods have resulted in an emerging field of plasmonics by properly introducing metallic nanostructures to manipulate light, enabling light trapping in active layers and thereby enhancing the performance of energy-harvesting devices.3 In addition, certain highly absorbing surfaces or structures with broadband absorption promising to extend the working wavelength of the solar energy spectrum (Figure 1) have been realized. The light-trapping effect, however, allows the thickness of materials and the costs of solar cells to decrease, which in turn benefits electricity collection when the minor carrier diffusion length in the active layer is not sufficiently long.In this review, we focus on light trapping induced by metallic nanostructures for solar energy collection. Corresponding applications are not only for photovoltaics, but also for solar thermal. In fact, solar thermal has a market with profit even higher than photovoltaics, yet

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Section: Multilayer Absorbersmentioning

confidence: 99%

Metallic nanostructures for light trapping in energy-harvesting devices

et al. 2014

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“…Titanium (Ti), as an abundant material in the earth, has lots of applications in the fields such as biomedicine, aerospace, mechanical, and microelectronic industries [1][2][3] as well as optical and decorative coatings [4,5] owing to its high mechanical strength, excellent thermal stability, good corrosion resistance, and intrinsic biocompatibility. Various techniques have been used to fabricate Ti films, such as: sputtering [1,[6][7][8][9], electron beam evaporation [3,10], pulsed filtered cathodic vacuum arc [11] and pulsed laser deposition [12].…”

Section: Introductionmentioning

confidence: 99%

Study of the thickness effect on the dielectric functions by utilizing a wedge-shaped Ti film sample with continuously varied thickness

Zhang

Cai

et al. 2015

Appl. Phys. A

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The dielectric functions of direct-current-sputtered wedge-shaped ultrathin titanium (Ti) film on K9 glass were investigated in this paper. The wedge-shaped Ti thin film was deposited under the identical conditions with continuously varied thickness. Atomic force microscope revealed that the thin film surface was very smooth with the surface roughness of about 0.5 nm. The dielectric functions of the wedge-shaped films in the wavelength range of 300-1200 nm were obtained by a focused-beam ellipsometer with the beam size on the sample about 200 lm. Results show that e 1 , the real part of the dielectric function, is negative almost in the whole spectrum region, proving that the film at the measured area is continuous and shows metallic behavior. On the other hand, e 1 decreases with the increase in the film thickness, while e 2 , the imaginary part of the dielectric function, has the opposite variation tendency. The changing of e 1 with film thickness is due to the reduced electron-electron interactions and enhanced metallic behavior. While for e 2 , it gets larger with the increase in the film thickness, which is mainly owing to the decrease in the tensile stress in the film.

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“…Since then, to achieve the spectral selectivity, various materials and structures such as the semiconductor, composite media, absorber-reflector tandem, and the materials with the rough or porous surface, cermet and multilayer films have been studied as the practical approaches for the solar selective absorber design and construction [2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Among these materials and structures, the multilayer-film-based structures are of special interest because of their good spectral properties and high thermal stability [9,10], which makes them particularly suitable for the photo-thermal solar energy conversion applied under the medium and high temperature conditions.…”

Section: Introductionmentioning

confidence: 99%

Nano-Cr-film-based solar selective absorber with high photo-thermal conversion efficiency and good thermal stability

Zhou

Shen

et al. 2012

Opt. Express

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Optical properties and thermal stability of the solar selective absorber based on the metal/dielectric four-layer film structure were investigated in the variable temperature region. Numerical calculations were performed to simulate the spectral properties of multilayer stacks with different metal materials and film thickness. The typical four-layer film structure using the transition metal Cr as the thin solar absorbing layer [SiO 2 (90nm)/Cr(10nm)/SiO 2 (80nm)/Al (≥100nm)] was fabricated on the Si or K9 glass substrate by using the magnetron sputtering method. The results indicate that the metal/dielectric film structure has a good spectral selective property suitable for solar thermal applications with solar absorption efficiency higher than 95% in the 400-1200nm wavelength range and a very low thermal emittance in the infrared region. The solar selective absorber with the thin Cr layer has shown a good thermal stability up to the temperature of 873K under vacuum atmosphere. The experimental results are in good agreement with the calculated spectral results. KeywordsSolar Energy, Thermo-optical materials, Multilayers, Thin films, optical properties Abstract: Optical properties and thermal stability of the solar selective absorber based on the metal/dielectric four-layer film structure were investigated in the variable temperature region. Numerical calculations were performed to simulate the spectral properties of multilayer stacks with different metal materials and film thickness. The typical four-layer film structure using the transition metal Cr as the thin solar absorbing layer [SiO 2 (90nm)/Cr(10nm)/SiO 2 (80nm)/Al (≥100nm)] was fabricated on the Si or K9 glass substrate by using the magnetron sputtering method. The results indicate that the metal/dielectric film structure has a good spectral selective property suitable for solar thermal applications with solar absorption efficiency higher than 95% in the 400-1200nm wavelength range and a very low thermal emittance in the infrared region. The solar selective absorber with the thin Cr layer has shown a good thermal stability up to the temperature of 873K under vacuum atmosphere. The experimental results are in good agreement with the calculated spectral results.

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High solar absorption of a multilayered thin film structure

Cited by 68 publications

References 7 publications

Metallic nanostructures for light trapping in energy-harvesting devices

Metallic nanostructures for light trapping in energy-harvesting devices

Study of the thickness effect on the dielectric functions by utilizing a wedge-shaped Ti film sample with continuously varied thickness

Nano-Cr-film-based solar selective absorber with high photo-thermal conversion efficiency and good thermal stability

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