Modulated photonic-crystal structures as broadband back reflectors in thin-film solar cells

Krč, Janez; Zeman, Miro; Luxembourg, S.L.; Topič, Marko

doi:10.1063/1.3109781

Cited by 51 publications

(33 citation statements)

References 11 publications

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“…Recently, exciting new strategies for improving light harvesting have gained tremendous interest, including nanopillar-and nanohole-type geometries, [1][2][3][4][5][6] plasmonics and guided modes, [7][8][9][10][11][12] and photonic crystals. [13][14][15] Light scattering at nanotextured interfaces provides a powerful and proven alternative to improve the optical performance of thinfilm silicon devices. [16][17][18][19][20][21][22][23][24][25][26][27] However, despite intensive experimental and theoretical efforts, neither the ideal interface morphology nor the ideal scattering characteristics have been identified to date.…”

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confidence: 99%

Nanoimprint Lithography for High-Efficiency Thin-Film Silicon Solar Cells

Battaglia¹,

Escarré²,

et al. 2011

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We demonstrate high-efficiency thin-film silicon solar cells with transparent nanotextured front electrodes fabricated via ultraviolet nanoimprint lithography on glass substrates. By replicating the morphology of state-of-the-art nanotextured zinc oxide front electrodes known for their exceptional light trapping properties, conversion efficiencies of up to 12.0% are achieved for micromorph tandem junction cells. Excellent light incoupling results in a remarkable summed short-circuit current density of 25.9 mA/cm 2 for amorphous top cell and microcrystalline bottom cell thicknesses of only 250 and 1100 nm, respectively. As efforts to maximize light harvesting continue, our study validates nanoimprinting as a versatile tool to investigate nanophotonic effects of a large variety of nanostructures directly on device performance.

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confidence: 99%

Nanoimprint Lithography for High-Efficiency Thin-Film Silicon Solar Cells

Battaglia¹,

Escarré²,

et al. 2011

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“…So far, the best experimental result for the enhancement of path length is, however, around 10 times the cells' thickness [17]. Some researchers use modulated distributed Bragg reflectors (DBR) to confine more broadband light, as shown in Figure 2 [18]. These researchers proposed a simple modulated PC for extending the region of high reflectance by piling up PCs with different periodicities corresponding to different "band-gaps."…”

Section: Photonic Crystal Techniquesmentioning

confidence: 99%

Efficiently Harvesting Sun Light for Silicon Solar Cells through Advanced Optical Couplers and A Radial p-n Junction Structure

Lee

Wu²,

Yang

et al. 2010

Energies

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Abstract:Silicon-based solar cells (SCs) promise to be an alternative energy source mainly due to: (1) a high efficiency-to-cost ratio, (2) the absence of environmentaldegradation issues, and (3) great reliability. Transition from wafer-based to thin-film SC significantly reduces the cost of SCs, including the cost from the material itself and the fabrication process. However, as the thickness of the absorption (or the active) layer decreases, the energy-conversion efficiency drops dramatically. As a consequence, we discuss here three techniques to increase the efficiency of silicon-based SCs: (1) photonic crystal (PC) optical couplers and (2) plasmonic optical couplers to increase efficiency of light absorption in the SCs, and (3) a radial p-n junction structure, decomposing light absorption and diffusion path into two orthogonal directions. The detailed mechanisms and recent research progress regarding these techniques are discussed in this review article.

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“…Recently, a dielectric one-dimensional photonic crystal (1D-PC), which is formed by periodically stacking high refractive index (high-n) layers and low refractive index (low-n) layers [25][26][27], also was regarded as a highly promising light-trapping concept. Because of the wide stop band, also called the photonic bandgap (PBG), with several hundreds of nanometers with nearly 100% reflectivity, 1D-PCs can be applied as broad spectrum back reflectors (BRs) (dielectric) in the TFSCs [25][26][27] or spectrally selective intermediate reflectors in the tandem solar cells [28]. Conventional 1D-PC BRs usually were treated as distributed Bragg reflectors (DBR), in which the individual layer thickness was calculated by the quarter-wavelength basis for the Bragg wavelength λ 0 [22][23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

“…Because of the wide stop band, also called the photonic bandgap (PBG), with several hundreds of nanometers with nearly 100% reflectivity, 1D-PCs can be applied as broad spectrum back reflectors (BRs) (dielectric) in the TFSCs [25][26][27] or spectrally selective intermediate reflectors in the tandem solar cells [28]. Conventional 1D-PC BRs usually were treated as distributed Bragg reflectors (DBR), in which the individual layer thickness was calculated by the quarter-wavelength basis for the Bragg wavelength λ 0 [22][23][24][25][26][27]. However, many pairs of layer thickness-contrasts can enable the 1D-PC PBG to cover the whole light-trapping range for TFSCs with the DBR structures [27].…”

Section: Introductionmentioning

confidence: 99%

“…In the last few years, a variety of novel light-trapping concepts and structures, including low pressure chemical vapor deposited (LPCVD) -ZnO [14], chemically-etched ZnO [15], textured glass [13], modulated surface textures [16], plasmonic light-trapping [17,18], honeycomb pattern substrates [19] and photonic structures [20][21][22][23][24][25][26][27][28][29][30][31], have been widely studied and utilized to improve the solar cell performances. Recently, a dielectric one-dimensional photonic crystal (1D-PC), which is formed by periodically stacking high refractive index (high-n) layers and low refractive index (low-n) layers [25][26][27], also was regarded as a highly promising light-trapping concept. Because of the wide stop band, also called the photonic bandgap (PBG), with several hundreds of nanometers with nearly 100% reflectivity, 1D-PCs can be applied as broad spectrum back reflectors (BRs) (dielectric) in the TFSCs [25][26][27] or spectrally selective intermediate reflectors in the tandem solar cells [28].…”

Section: Introductionmentioning

confidence: 99%

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Photonic Structures for Light Trapping in Thin Film Silicon Solar Cells: Design and Experiment

et al. 2017

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Abstract:One of the foremost challenges in designing thin-film silicon solar cells (TFSC) is devising efficient light-trapping schemes due to the short optical path length imposed by the thin absorber thickness. The strategy relies on a combination of a high-performance back reflector and an optimized texture surface, which are commonly used to reflect and scatter light effectively within the absorption layer, respectively. In this paper, highly promising light-trapping structures based on a photonic crystal (PC) for TFSCs were investigated via simulation and experiment. Firstly, a highly-reflective one-dimensional photonic crystal (1D-PC) was designed and fabricated. Then, two types of 1D-PC-based back reflectors (BRs) were proposed: Flat 1D-PC with random-textured aluminum-doped zinc oxide (AZO) or random-textured 1D-PC with AZO. These two newly-designed BRs demonstrated not only high reflectivity and sufficient conductivity, but also a strong light scattering property, which made them efficient candidates as the electrical contact and back reflector since the intrinsic losses due to the surface plasmon modes of the rough metal BRs can be avoided. Secondly, conical two-dimensional photonic crystal (2D-PC)-based BRs were investigated and optimized for amorphous a-SiGe:H solar cells. The maximal absorption value can be obtained with an aspect ratio of 1/2 and a period of 0.75 µm. To improve the full-spectral optical properties of solar cells, a periodically-modulated PC back reflector was proposed and experimentally demonstrated in the a-SiGe:H solar cell. This periodically-modulated PC back reflector, also called the quasi-crystal structure (QCS), consists of a large periodic conical PC and a randomly-textured Ag layer with a feature size of 500-1000 nm. The large periodic conical PC enables conformal growth of the layer, while the small feature size of Ag can further enhance the light scattering. In summary, a comprehensive study of the design, simulation and fabrication of 1D-PC-and 2D-PC-based back reflectors for TFSCs was carried out. Total absorption and device performance enhancement were achieved with the novel PC light-trapping systems because of their high reflectivity or high scattering property. Further research is necessary to illuminate the optimal structure design of PC-based back reflectors and high solar cell efficiency.

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Modulated photonic-crystal structures as broadband back reflectors in thin-film solar cells

Cited by 51 publications

References 11 publications

Nanoimprint Lithography for High-Efficiency Thin-Film Silicon Solar Cells

Nanoimprint Lithography for High-Efficiency Thin-Film Silicon Solar Cells

Efficiently Harvesting Sun Light for Silicon Solar Cells through Advanced Optical Couplers and A Radial p-n Junction Structure

Photonic Structures for Light Trapping in Thin Film Silicon Solar Cells: Design and Experiment

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