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Transmission enhancement based on strong interference in metal-semiconductor layered film for energy harvesting.

Li Q, Du K, Mao K, Fang X, Zhao D, Ye H, Qiu M - Sci Rep (2016)

Bottom Line: In a metallic film coated with a thin semiconductor film, both transmission and absorption are simultaneously enhanced as a result of dramatically reduced reflection.These planar layered films for transmission enhancement feature ultrathin thickness, broadband and wide-angle operation, and reduced resistance.This strategy relies on no patterned nanostructures and thereby may power up a wide spectrum of energy-harvesting applications such as thin-film photovoltaics and surface photocatalysis.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027, China.

ABSTRACT
A fundamental strategy to enhance optical transmission through a continuous metallic film based on strong interference dominated by interface phase shift is developed. In a metallic film coated with a thin semiconductor film, both transmission and absorption are simultaneously enhanced as a result of dramatically reduced reflection. For a 50-nm-thick Ag film, experimental transmission enhancement factors of 4.5 and 9.5 are realized by exploiting Ag/Si non-symmetric and Si/Ag/Si symmetric geometries, respectively. These planar layered films for transmission enhancement feature ultrathin thickness, broadband and wide-angle operation, and reduced resistance. Considering one of their potential applications as transparent metal electrodes in solar cells, a calculated 182% enhancement in the total transmission efficiency relative to a single metallic film is expected. This strategy relies on no patterned nanostructures and thereby may power up a wide spectrum of energy-harvesting applications such as thin-film photovoltaics and surface photocatalysis.

No MeSH data available.


Related in: MedlinePlus

Symmetric Si/Ag/Si triple-layered film for further enhanced transmission.(a) A representation (both schematic diagram and SEM image of cross-section) of the proposed symmetric Si/Ag/Si triple-layered film. The scale bar is 100 nm. (b,c) are measured and simulated transmission of the proposed symmetric Si/Ag/Si triple-layered film at normal incidence, respectively.
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f5: Symmetric Si/Ag/Si triple-layered film for further enhanced transmission.(a) A representation (both schematic diagram and SEM image of cross-section) of the proposed symmetric Si/Ag/Si triple-layered film. The scale bar is 100 nm. (b,c) are measured and simulated transmission of the proposed symmetric Si/Ag/Si triple-layered film at normal incidence, respectively.

Mentions: Equation (2) indicates that the transmission T reaches the maximum at τr = τt. Therefore, a symmetric structure can further enhance the transmission. Here another Si layer beneath the Ag layer is added to form a symmetric Si/Ag/Si triple-layered film, as illustrated in Fig. 5a. Figure 5a also presents the SEM image of the cross-section of the Si/Ag/Si triple-layered film. The boundary between the substrate layer and Si/Ag/Si layer is also clear. Fig. 5b,c show the experimental and simulated transmission for both Ag/Si non-symmetric double-layered and Si/Ag/Si symmetric triple-layered films with different Si thicknesses (30 nm Ag thickness), respectively. The experimental transmission, transmission enhancement factor, reflection and absorption for Si/Ag/Si triple-layered films with all four Ag thicknesses (20, 30, 40 and 50 nm) are presented in Figs S2 to S5 in the Supplementary Information, respectively. It can be distinctly seen that Si/Ag/Si symmetric configurations show higher optical transmission and broader windows than the Ag/Si asymmetric configuration. For example, the experimental maximum transmission for Si/Ag/Si (25/30/25 nm) symmetric film is 45% at 630 nm, well above that for Ag/Si (30/25 nm) asymmetric film (~30% at 660 nm). For the 50-nm-thick Ag film at 700 nm wavelength, the transmission is increased from 1.3% to 12% after coating two 25-nm-thick Si layers, exhibiting an over ninth enhancement in the transmission (Figs S2d and S3d). The simulated transmission is generally higher than that of corresponding measured transmission. This can be attributed to the light scattering loss induced by the rough film surfaces. Especially for triple-layered films, an extra rough film surface can lead to extra scattering loss.


Transmission enhancement based on strong interference in metal-semiconductor layered film for energy harvesting.

Li Q, Du K, Mao K, Fang X, Zhao D, Ye H, Qiu M - Sci Rep (2016)

Symmetric Si/Ag/Si triple-layered film for further enhanced transmission.(a) A representation (both schematic diagram and SEM image of cross-section) of the proposed symmetric Si/Ag/Si triple-layered film. The scale bar is 100 nm. (b,c) are measured and simulated transmission of the proposed symmetric Si/Ag/Si triple-layered film at normal incidence, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4940859&req=5

f5: Symmetric Si/Ag/Si triple-layered film for further enhanced transmission.(a) A representation (both schematic diagram and SEM image of cross-section) of the proposed symmetric Si/Ag/Si triple-layered film. The scale bar is 100 nm. (b,c) are measured and simulated transmission of the proposed symmetric Si/Ag/Si triple-layered film at normal incidence, respectively.
Mentions: Equation (2) indicates that the transmission T reaches the maximum at τr = τt. Therefore, a symmetric structure can further enhance the transmission. Here another Si layer beneath the Ag layer is added to form a symmetric Si/Ag/Si triple-layered film, as illustrated in Fig. 5a. Figure 5a also presents the SEM image of the cross-section of the Si/Ag/Si triple-layered film. The boundary between the substrate layer and Si/Ag/Si layer is also clear. Fig. 5b,c show the experimental and simulated transmission for both Ag/Si non-symmetric double-layered and Si/Ag/Si symmetric triple-layered films with different Si thicknesses (30 nm Ag thickness), respectively. The experimental transmission, transmission enhancement factor, reflection and absorption for Si/Ag/Si triple-layered films with all four Ag thicknesses (20, 30, 40 and 50 nm) are presented in Figs S2 to S5 in the Supplementary Information, respectively. It can be distinctly seen that Si/Ag/Si symmetric configurations show higher optical transmission and broader windows than the Ag/Si asymmetric configuration. For example, the experimental maximum transmission for Si/Ag/Si (25/30/25 nm) symmetric film is 45% at 630 nm, well above that for Ag/Si (30/25 nm) asymmetric film (~30% at 660 nm). For the 50-nm-thick Ag film at 700 nm wavelength, the transmission is increased from 1.3% to 12% after coating two 25-nm-thick Si layers, exhibiting an over ninth enhancement in the transmission (Figs S2d and S3d). The simulated transmission is generally higher than that of corresponding measured transmission. This can be attributed to the light scattering loss induced by the rough film surfaces. Especially for triple-layered films, an extra rough film surface can lead to extra scattering loss.

Bottom Line: In a metallic film coated with a thin semiconductor film, both transmission and absorption are simultaneously enhanced as a result of dramatically reduced reflection.These planar layered films for transmission enhancement feature ultrathin thickness, broadband and wide-angle operation, and reduced resistance.This strategy relies on no patterned nanostructures and thereby may power up a wide spectrum of energy-harvesting applications such as thin-film photovoltaics and surface photocatalysis.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027, China.

ABSTRACT
A fundamental strategy to enhance optical transmission through a continuous metallic film based on strong interference dominated by interface phase shift is developed. In a metallic film coated with a thin semiconductor film, both transmission and absorption are simultaneously enhanced as a result of dramatically reduced reflection. For a 50-nm-thick Ag film, experimental transmission enhancement factors of 4.5 and 9.5 are realized by exploiting Ag/Si non-symmetric and Si/Ag/Si symmetric geometries, respectively. These planar layered films for transmission enhancement feature ultrathin thickness, broadband and wide-angle operation, and reduced resistance. Considering one of their potential applications as transparent metal electrodes in solar cells, a calculated 182% enhancement in the total transmission efficiency relative to a single metallic film is expected. This strategy relies on no patterned nanostructures and thereby may power up a wide spectrum of energy-harvesting applications such as thin-film photovoltaics and surface photocatalysis.

No MeSH data available.


Related in: MedlinePlus