Toward the Lambertian Limit of Light Trapping in Thin Nanostructured Silicon Solar Cells

Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States.
Nano Letters (Impact Factor: 13.59). 10/2010; 10(11):4692-6. DOI: 10.1021/nl1029804
Source: PubMed


We examine light trapping in thin silicon nanostructures for solar cell applications. Using group theory, we design surface nanostructures with an absorptance exceeding the Lambertian limit over a broad band at normal incidence. Further, we demonstrate that the absorptance of nanorod arrays closely follows the Lambertian limit for isotropic incident radiation. These effects correspond to a reduction in silicon mass by 2 orders of magnitude, pointing to the promising future of thin crystalline silicon solar cells.

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    • "Most strategies for enhancing thin-film cell absorption pursued up to this point have used cell surface texturing to scatter photons into a wider range of angles into the cell with the aim of approaching the Yablonovitch limit [10] [11] [12] [13] [14]. However, the PV cell efficiency can also be increased by limiting the angular range through which photons (both trapped and emitted in the process of radiative recombination) can escape the cell [15] [16] [17] [18]. "
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    ABSTRACT: We show via numerical simulations that the absorption and solar energy conversion efficiency of a thin-film photovoltaic (PV) cell can be significantly enhanced by embedding it into an optical cavity. A reflective hemi-ellipsoid with an aperture for sunlight placed over a tilted PV cell reflects unabsorbed photons back to the cell, allowing for multiple opportunities for absorption. Ray tracing simulations predict that with the proposed cavity a textured thin-film silicon cell can exceed the Yablonovitch (Lambertian) limit for absorption across a broad wavelength range, while the performance of the cavity-embedded planar PV cell approaches that of the cell with the surface texturing.
    Full-text · Article · May 2015 · Journal of Optics
    • "Nano photonic structures have become one of the significant elements of light harvesting devices such as thin film solar cells, which are expected to offer better absorption enhancement and hence conversion efficiency [1]. The efficiency of the solar cell is affected by absorption of the material, photon flux, broadness of the light spectrum and the surface volume recombination in the material. "
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    ABSTRACT: Random textures are proved to be better for energy harvesting in solar cells. In this research, we have studied the absorption properties of a random dielectric medium with plasmonic nanostructures in it. This structure has shown significant enhancement in broad band absorption of light spectrum and higher extinction of near infrared wavelengths. We also discuss several strategies to improve the solar cell efficiency based on dielectric and plasmonic random media. Finally, a comparative study of solar cell efficiencies with flat, periodic and random structures as active medium and back reflectors is carried out with a proposal for possible potential solar cell configurations. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
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    • "It is therefore of great interest to the industry to further reduce the optical loss in order to increase the conversion efficiency (EFF). Recently, silicon nanostructures have attracted great attentions because of their excellent antireflection and light trapping effect [1] [2] [3] [4], which make them promising candidates for reducing both the demand on the quality factor and quantity of silicon material [5]. But researchers have also encountered in these structures the difficulties of enhanced surface and Auger recombination at "
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    ABSTRACT: We report the realization of both excellent optical and electrical properties of nanostructured multicrystalline silicon solar cells by a simple and industrially compatible technique of surface morphology modification. The nanostructures are prepared by Ag-catalyzed chemical etching and subsequent NaOH treatment with controllable geometrical parameters and surface area enhancement ratio. We have examined in detail the influence of different surface area enhancement ratios on reflectance, carrier recombination characteristics and cell performance. By conducting a quantitative analysis of these factors, we have successfully demonstrated a higher-than-traditional output performance of nanostructured multicrystalline silicon solar cells with a low average reflectance of 4.93%, a low effective surface recombination velocity of 6.59 m s(-1), and a certified conversion efficiency of 17.75% on large size (156 × 156 mm(2)) silicon cells, which is ∼0.3% higher than the acid textured counterparts. The present work opens a potential prospect for the mass production of nanostructured solar cells with improved efficiencies.
    Full-text · Article · Mar 2015 · Nanotechnology
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