Demonstration of enhanced absorption in thin film Si solar cells with textured photonic crystal back reflector

Zeng, Lirong; Bermel, Peter; Yi, Yasha; Alamariu, Bernard A.; Broderick, Kurt; Liu, Jifeng; Hong, Ching-yin; Duan, Xili; Joannopoulos, John D.; Kimerling, Lionel C.

doi:10.1063/1.3039787

Cited by 226 publications

(137 citation statements)

References 19 publications

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“…Further, the angular performance of the devices is impressive; 80% of power efficiency enhancement is preserved even through incident angles as high as 45 ° owing to the preservation of the reflection properties of the photonic crystal bandgap and the diffraction properties of the gratings at large angles. Short circuit current enhancement of 19% was observed by another group [ 94 ] in a thinner 5 μ m device. Note that unlike planar DBRs, where more layers improve the photonic crystal performance, simulations show that for DBRs with integrated gratings, parasitic losses due to grating coupling to guided modes within the DBR instead of the active layer could degrade performance [ 95 ].…”

Section: Photonic Crystal Reflectorsmentioning

confidence: 88%

Nanostructures for photon management in solar cells

Narasimhan

Cui

2013

Nanophotonics

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Abstract:The concurrent development of high-performance materials, new device and system architectures, and nanofabrication processes has driven widespread research and development in the field of nanostructures for photon management in photovoltaics. The fundamental goals of photon management are to reduce incident light reflection, improve absorption, and tailor the optical properties of a device for use in different types of energy conversion systems. Nanostructures rely on a core set of phenomena to attain these goals, including gradation of the refractive index, coupling to waveguide modes through surface structuring, and modification of the photonic band structure of a device. In this review, we present recent developments in the field of nanostructures for photon management in solar cells with applications across different materials and system architectures. We focus both on theoretical and numerical studies and on progress in fabricating solar cells containing photonic nanostructures. We show that nanoscale light management structures have yielded real efficiency gains in many types of photovoltaic devices; however, we note that important work remains to ensure that improved optical performance does not come at the expense of poor electrical properties.

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Section: Photonic Crystal Reflectorsmentioning

confidence: 88%

Nanostructures for photon management in solar cells

Narasimhan

Cui

2013

Nanophotonics

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“…It has been shown that there is good agreement between modeling and experimental results for a uni-periodic grating applied to a 5 lm thick Si cell. 20 Recently, light trapping obtained from a periodic plasmon structure has been shown to exceed that of the Asahi U-type glass, 21 which is the thin-film solar cell standard. A similar result is also presented in Ref.…”

Section: -mentioning

confidence: 99%

Comparison of periodic light-trapping structures in thin crystalline silicon solar cells

Gjessing

Sudbø

Marstein

2011

Journal of Applied Physics

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Material costs may be reduced and electrical properties improved by utilizing thinner solar cells. Light trapping makes it possible to reduce wafer thickness without compromising optical absorption in a silicon solar cell. In this work we present a comprehensive comparison of the light-trapping properties of various bi-periodic structures with a square lattice. The geometries that we have investigated are cylinders, cones, inverted pyramids, dimples (half-spheres), and three more advanced structures, which we have called the roof mosaic, rose, and zigzag structure. Through simulations performed with a 20 μm thick Si cell, we have optimized the geometry of each structure for light trapping, investigated the performance at oblique angles of incidence, and computed efficiencies for the different diffraction orders for the optimized structures. We find that the lattice periods that give optimal light trapping are comparable for all structures, but that the light-trapping ability varies considerably between the structures. A far-field analysis reveals that the superior light-trapping structures exhibit a lower symmetry in their diffraction patterns. The best result is obtained for the zigzag structure with a simulated photo-generated current Jph of 37.3 mA/cm2, a light-trapping efficiency comparable to that of Lambertian light-trapping.

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“…For example, surface texturing 1 and reflectors 2 are used to improve the in-coupling of light and enhance optical path length in many types of conventional thickand thin-film solar cells 3 . When the structure size is comparable to or even smaller than the wavelength, two main light-trapping approaches, photonic crystals 4,5 and plasmonic nanostructures [6][7][8] have been extensively studied. A photonic crystal can be used either as an omnidirectional lossless reflector 4 or a diffractive element outside the photoactive layer 5,9 , or as a photoactive absorber [10][11][12][13][14][15][16][17] to couple incident light into quasi-guided modes.…”

mentioning

confidence: 99%

“…When the structure size is comparable to or even smaller than the wavelength, two main light-trapping approaches, photonic crystals 4,5 and plasmonic nanostructures [6][7][8] have been extensively studied. A photonic crystal can be used either as an omnidirectional lossless reflector 4 or a diffractive element outside the photoactive layer 5,9 , or as a photoactive absorber [10][11][12][13][14][15][16][17] to couple incident light into quasi-guided modes. Plasmonic nanostructures enhance light absorption because they can scatter incident light into wave-guided modes 18 or surface plasmon-polariton modes 19,20 , or increase the optical electric field around nanostructures 21 .…”

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confidence: 99%

Broadband light management using low-Q whispering gallery modes in spherical nanoshells

et al. 2012

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Light trapping across a wide band of frequencies is important for applications such as solar cells and photodetectors. Here, we demonstrate a new approach to light management by forming whispering-gallery resonant modes inside a spherical nanoshell structure. The geometry of the structure gives rise to a low quality-factor, facilitating the coupling of light into the resonant modes and substantial enhancement of the light path in the active material, thus dramatically improving absorption. using nanocrystalline silicon (nc-si) as a model system, we observe broadband absorption enhancement across a large range of incident angles. The absorption of a single layer of 50-nm-thick spherical nanoshells is equivalent to a 1-µm-thick planar nc-si film. This light-trapping structure could enable the manufacturing of high-throughput ultra-thin film absorbers in a variety of material systems that demand shorter deposition time, less material usage and transferability to flexible substrates.

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Demonstration of enhanced absorption in thin film Si solar cells with textured photonic crystal back reflector

Cited by 226 publications

References 19 publications

Nanostructures for photon management in solar cells

Nanostructures for photon management in solar cells

Comparison of periodic light-trapping structures in thin crystalline silicon solar cells

Broadband light management using low-Q whispering gallery modes in spherical nanoshells

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