Nanoimprint Lithography of Light Trapping Structures in Sol-gel Coatings for Thin Film Silicon Solar Cells

AbstractFor thin-film silicon solar cells, light trapping schemes are of uppermost importance to harvest all available sunlight. Typically, superstrates with randomly textured TCO front layers are used to scatter the light diffusively in pin-cells on glass. Here, we investigate methods to texture opaque substrates with both random and periodic textures, for use in nip-cells on metal foil. We applied an electrically insulating SiOx-polymer coating on a stainless steel substrate, and textured this barrier layer by nanoimprint. On this barrier layer the back contact is deposited for further use in the solar cell stack. Replication of masters with various random and periodic sub-micron patterns was tested, and, using scanning electron microscopy, replicas were found to compare well with the originals. The embossing of the barrier layer does not diminish its electrically isolating properties, and thus adds extra functionality to this layer. Masters with U-grooves of various sub-micrometer widths have been used to investigate the optimal dimensions of regular patterns for light trapping in the silicon layers. Angular reflection distributions were measured to evaluate the light scattering properties of both periodic and random patterns. These periodic patterns, comprising diffraction gratings, show promising results in scattering the light to specific angles, enhancing the total internal reflection in the solar cell.

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Nanoimprint lithography of textures for light trapping in thin film silicon solar cells

physica status solidi (a) ◽

10.1002/pssa.201200887 ◽

2012 ◽

Vol 210 (4) ◽

pp. 707-710 ◽

Cited By ~ 13

Author(s):

Wim Soppe ◽

Maarten Dörenkämper ◽

Jean-Baptiste Notta ◽

Paul Pex ◽

Wilfried Schipper ◽

...

Keyword(s):

Thin Film ◽

Solar Cells ◽

Nanoimprint Lithography ◽

Light Trapping ◽

Silicon Solar Cells ◽

Thin Film Silicon

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Improved light trapping effect for thin-film silicon solar cells fabricated on double-textured white glass substrate

Canadian Journal of Physics ◽

10.1139/cjp-2013-0621 ◽

2014 ◽

Vol 92 (7/8) ◽

pp. 920-923 ◽

Cited By ~ 6

Author(s):

Hidetoshi Wada ◽

Keiichi Nishikubo ◽

Porponth Sichanugrist ◽

Makoto Konagai

Keyword(s):

Thin Film ◽

Solar Cells ◽

Solar Cell ◽

Light Trapping ◽

Short Circuit ◽

Silicon Solar Cells ◽

Organic Chemical ◽

Trapping Effect ◽

Thin Film Silicon ◽

Vapor Deposition Technique

Light trapping effect using rough surface transparent conductive oxide (TCO) is one of the best ways to achieve high efficiency thin-film silicon solar cells. Several types of rough ZnO film fabricated by metal organic chemical vapor deposition technique onto the glass, which are etched by reactive ion etching, have been proposed so far as promising TCO substrates. In this paper, newly developed ZnO substrate with extremely high light scattering property comparing with typical pyramidal texture one was developed. By applying this newly developed ZnO substrate to the solar cell, higher short circuit current of about 2% has been achieved comparing with typical pyramidal texture one without sacrificing other parameters. This result showed that the newly developed substrate is suitable as a front TCO substrate for high performance thin-film silicon solar cell.

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Light-trapping in Thin Film Silicon Solar Cells with a Combination of Periodic and Randomly Textured Back-reflectors

MRS Proceedings ◽

10.1557/opl.2012.888 ◽

2012 ◽

Vol 1426 ◽

pp. 117-123 ◽

Cited By ~ 1

Author(s):

Sambit Pattnaik ◽

Nayan Chakravarty ◽

Rana Biswas ◽

D. Slafer ◽

Vikram Dalal

Keyword(s):

Thin Film ◽

Solar Cells ◽

Light Absorption ◽

Nanoimprint Lithography ◽

Light Trapping ◽

Silicon Solar Cells ◽

Long Wavelength ◽

Thin Film Silicon ◽

Back Reflectors ◽

Back Reflector

ABSTRACTLight trapping is essential to harvest long wavelength red and near-infrared photons in thin film silicon solar cells. Traditionally light trapping has been achieved with a randomly roughened Ag/ZnO back reflector, which scatters incoming light uniformly through all angles, and enhances currents and cell efficiencies over a flat back reflector. A new approach using periodically textured photonic-plasmonic arrays has been recently shown to be very promising for harvesting long wavelength photons, through diffraction of light and plasmonic light concentration. Here we investigate the combination of these two approaches of random scattering and plasmonic effects to increase cell performance even further. An array of periodic conical back reflectors was fabricated by nanoimprint lithography and coated with Ag. These back reflectors were systematically annealed to generate different amounts of random texture, at smaller spatial scales, superimposed on a larger scale periodic texture. nc-Si solar cells were grown on flat, periodic photonic-plasmonic substrates, and randomly roughened photonic-plasmonic substrates. There were large improvements (>20%) in the current and light absorption of the photonic-plasmonic substrates relative to flat. The additional random features introduced on the photonic-plasmonic substrates did not improve the current and light absorption further, over a large range of randomization features.

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Modeling of Advanced Light Trapping Approaches in Thin-Film Silicon Solar Cells

MRS Proceedings ◽

10.1557/opl.2011.955 ◽

2011 ◽

Vol 1321 ◽

Cited By ~ 4

Author(s):

Miro Zeman ◽

Olindo Isabella ◽

Klaus Jäger ◽

Pavel Babal ◽

Serge Solntsev ◽

...

Keyword(s):

Thin Film ◽

Zinc Oxide ◽

Solar Cells ◽

Solar Cell ◽

Light Trapping ◽

Spherical Particles ◽

Silicon Solar Cells ◽

Amorphous Silicon Solar Cell ◽

Thin Film Silicon ◽

Negative Effect

ABSTRACTDue to the increasing complexity of thin-film silicon solar cells, the role of computer modeling for analyzing and designing these devices becomes increasingly important. The ASA program was used to study two of these advanced devices. The simulations of an amorphous silicon solar cell with silver nanoparticles embedded in a zinc oxide back reflector demonstrated the negative effect of the parasitic absorption in the particles. When using optical properties of perfectly spherical particles a modest enhancement in the external quantum efficiency was found. The simulations of a tandem micromorph solar cell, in which a zinc oxide based photonic crystal-like multilayer was incorporated as an intermediate reflector (IR), demonstrated that the IR resulted in an enhanced photocurrent in the top cell and could be used to optimize the current matching of the top and bottom cell.

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Periodic Structures for Improved Light Management in Thin-film Silicon Solar Cells

MRS Proceedings ◽

10.1557/proc-1101-kk08-01 ◽

2008 ◽

Vol 1101 ◽

Cited By ~ 2

Author(s):

Janez Krc ◽

Andrej Campa ◽

Stefan L. Luxembourg ◽

Miro Zeman ◽

Marko Topic

Keyword(s):

Thin Film ◽

Solar Cells ◽

Solar Cell ◽

Photonic Crystal ◽

Amorphous Silicon ◽

Periodic Structures ◽

Light Trapping ◽

Silicon Solar Cells ◽

Thin Film Silicon ◽

Light Management

AbstractAdvanced light management in thin-film solar cells is important in order to improve the photo-current and, thus, to raise up the conversion efficiencies of the solar cells. In this article two types of periodic structures ¡V one-dimensional diffraction gratings and photonic crystals,are analyzed in the direction of showing their potential for improved light trapping in thin-film silicon solar cells. The anti-reflective effects and enhanced scattering at the gratings with the triangular and rectangular features are studied by means of two-dimensional optical simulations. Simulations of the complete microcrystalline solar cell incorporating the gratings at all interfaces are presented. Critical optical issues to be overcome for achieving the performances of the cells with the optimized randomly textured interfaces are pointed out. Reflectance measurements for the designed 12 layer photonic crystal stack consisting of amorphous silicon nitride and amorphous silicon layers are presented and compared with the simulations. High reflectance (up to 99 %) of the stack is measured for a broad wavelength spectrum. By means of optical simulations the potential for using a simple photonic crystal structure as a back reflector in an amorphous silicon solar cell is demonstrated.

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A hybrid resist hemispherical-pit array layer for light trapping in thin film silicon solar cells via UV nanoimprint lithography

Journal of Materials Chemistry C ◽

10.1039/c4tc00605d ◽

2014 ◽

Vol 2 (30) ◽

pp. 6140-6147 ◽

Cited By ~ 8

Author(s):

Peihua Wangyang ◽

Yanchang Gan ◽

Qingkang Wang ◽

Xuesong Jiang

Keyword(s):

Thin Film ◽

Solar Cells ◽

Nanoimprint Lithography ◽

Light Trapping ◽

Silicon Solar Cells ◽

Tandem Solar Cells ◽

Relative Improvement ◽

Thin Film Silicon ◽

Average Reflectance

Micromorph tandem solar cells coated with a HP array layer were fabricated by UV NIL. The HP array layer could reduce the average reflectance of the solar cells from 7.7% to 1.8%. And a relative improvement of efficiency of up to 4.1% is observed as compared to the bare solar cells.

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