Epitaxially grown emitters for thin film silicon solar cells result in 16% efficiency

Nieuwenhuysen, Kris Van; Payo, María Recamán; Kuzma-Filipek, I.; Hoeymissen, Jan Van; Beaucarne, G.; Poortmans, Jef

doi:10.1016/j.tsf.2009.10.061

Cited by 26 publications

(11 citation statements)

References 2 publications

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“…In contrast, broadband angle restrictors can result in narrower escape angles, and show significant efficiency benefits and reductions in the optimal cell thickness, but might remain limited due to the loss of diffuse light. Based on these calculations, recent results with combined interdigitated back contact and heterojunction with intrinsic layer technology [1], and recently demonstrated technologies for micro-CPC-based structures [7], [38] and high-quality thin c-Si substrates [39]- [42] make this concept particularly relevant today. We envision broadband angle restriction with a CPC-based ray optical structure used in either a flat plate geometry or with low to moderate external concentration to demonstrate enhanced performance of crystalline silicon solar cells as they approach fundamental materials limitations.…”

Section: Discussionmentioning

confidence: 99%

Limiting Light Escape Angle in Silicon Photovoltaics: Ideal and Realistic Cells

Kosten

Newman

Lloyd

et al. 2015

IEEE J. Photovoltaics

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Restricting the light escape angle within a solar cell significantly enhances light trapping, resulting in potentially higher efficiency in thinner cells. Using an improved detailed balance model for silicon and neglecting diffuse light, we calculate an efficiency gain of 3% ab s for an ideal Si cell of 3-μm thickness and the escape angle restricted to 2.767°under AM1.5 direct illumination. Applying the model to current high-efficiency cell technologies, we find that a heterojunction-type device with better surface and contact passivation is better suited to escape angle restriction than a homojunction type device. In these more realistic cell models, we also find that there is little benefit gained by restricting the escape angle to less than 10°. The benefits of combining moderate escape angle restriction with low to moderate concentration offers further efficiency gains. Finally, we consider two potential structures for escape angle restriction: a narrowband graded index optical multilayer and a broadband ray optical structure. The broadband structure, which provides greater angle restriction, allows for higher efficiencies and much thinner cells than the narrowband structure.

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Section: Discussionmentioning

confidence: 99%

Limiting Light Escape Angle in Silicon Photovoltaics: Ideal and Realistic Cells

Kosten

Newman

Lloyd

et al. 2015

IEEE J. Photovoltaics

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“…The concept of crystalline thin‐film Si based solar cells fabricated on low‐cost substrates has been widely discussed in literature for more than one decade and still is under consideration as a promising approach for low‐cost Si based PV . One of the promising options is based on a crystalline silicon (c‐Si) thin‐film solar cells fabricated on top of low‐cost c‐Si supporting substrates and is related to the epitaxial wafer‐equivalent (EpiWE) .…”

Section: Introductionmentioning

confidence: 99%

Microstructural characterization of Si wafers processed by multi-wire sawing of hot pressed silicon powder based ingots

Buchwald

Würzner

Möller

et al. 2014

Phys. Status Solidi A

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The purpose of this work is to verify the possibility to process highly doped Si supporting substrates using a 2-step process: (i) sintering of a low-cost Si powder based ingot using hot pressing and a ELKEM Silgrain material as a feedstock; and (ii) wafering of such ingots using multi-wire sawing technique similar to that, which is used for cast multi-Si or Cz-Si grown ingots. Moreover, the possibility to dope Si powder ingot at sintering temperatures below melting point of Si, using a mixture of Si and boron powders to fabricate highly conductive Si wafers is verified as well. The slurry technique has been chosen for multi-wire sawing of sintered Si powder based ingots. Surface properties of Si powder based substrates as well as their chemical composition have been studied by optical microscopy imaging and energy-dispersive X-ray spectroscopy (EDX). Although the overall concentrations of oxygen, carbon and possibly also metal impurities, which are initially present in a low-cost Si feedstock, are too high to achieve acceptable semiconducting properties, it is concluded, that sintered Si powder based wafers have high enough conductivity (resistivity similar to 0.001 Omega cm) to serve as supporting substrates for low cost Si wafer equivalent structures

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“…evaporated silicon) 2 . For such originally planar Si layer alternative light trapping approaches, such as diffuse white paint reflector 3 , silicon plasma texturing 4 or high refractive index nanoparticle reflector 5 have been suggested.…”

Section: Introductionmentioning

confidence: 99%

Polycrystalline Silicon Thin-film Solar cells with Plasmonic-enhanced Light-trapping

Varlamov

Rao

Söderström

2012

JoVE

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One of major approaches to cheaper solar cells is reducing the amount of semiconductor material used for their fabrication and making cells thinner. To compensate for lower light absorption such physically thin devices have to incorporate light-trapping which increases their optical thickness. Light scattering by textured surfaces is a common technique but it cannot be universally applied to all solar cell technologies. Some cells, for example those made of evaporated silicon, are planar as produced and they require an alternative light-trapping means suitable for planar devices. Metal nanoparticles formed on planar silicon cell surface and capable of light scattering due to surface plasmon resonance is an effective approach. The paper presents a fabrication procedure of evaporated polycrystalline silicon solar cells with plasmonic light-trapping and demonstrates how the cell quantum efficiency improves due to presence of metal nanoparticles. To fabricate the cells a film consisting of alternative boron and phosphorous doped silicon layers is deposited on glass substrate by electron beam evaporation. An Initially amorphous film is crystallised and electronic defects are mitigated by annealing and hydrogen passivation. Metal grid contacts are applied to the layers of opposite polarity to extract electricity generated by the cell. Typically, such a ~2 μm thick cell has a short-circuit current density (Jsc) of 14-16 mA/cm(2), which can be increased up to 17-18 mA/cm(2) (~25% higher) after application of a simple diffuse back reflector made of a white paint. To implement plasmonic light-trapping a silver nanoparticle array is formed on the metallised cell silicon surface. A precursor silver film is deposited on the cell by thermal evaporation and annealed at 23°C to form silver nanoparticles. Nanoparticle size and coverage, which affect plasmonic light-scattering, can be tuned for enhanced cell performance by varying the precursor film thickness and its annealing conditions. An optimised nanoparticle array alone results in cell Jsc enhancement of about 28%, similar to the effect of the diffuse reflector. The photocurrent can be further increased by coating the nanoparticles by a low refractive index dielectric, like MgF(2;), and applying the diffused reflector. The complete plasmonic cell structure comprises the polycrystalline silicon film, a silver nanoparticle array, a layer of MgF(2;), and a diffuse reflector. The Jsc for such cell is 21-23 mA/cm(2), up to 45% higher than Jsc of the original cell without light-trapping or ~25% higher than Jsc for the cell with the diffuse reflector only.

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Epitaxially grown emitters for thin film silicon solar cells result in 16% efficiency

Cited by 26 publications

References 2 publications

Limiting Light Escape Angle in Silicon Photovoltaics: Ideal and Realistic Cells

Limiting Light Escape Angle in Silicon Photovoltaics: Ideal and Realistic Cells

Microstructural characterization of Si wafers processed by multi-wire sawing of hot pressed silicon powder based ingots

Polycrystalline Silicon Thin-film Solar cells with Plasmonic-enhanced Light-trapping

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