Mesoscale trumps nanoscale: metallic mesoscale contact morphology for improved light trapping, optical absorption and grid conductance in silicon solar cells

doi:10.1364/OE.26.00A275

Title: Mesoscale trumps nanoscale: metallic mesoscale contact morphology for improved light trapping, optical absorption and grid conductance in silicon solar cells

Abstract

Here, we report on a computational study exploring the design of mesoscale metallic front contacts for solar cells. We investigated silver contact structures with circle, triangle and square cross-sections for various length scales and surface coverages. We found that for ‘nanoscale’ contacts with widths between 10 nm and 1000 nm, resonant coupling actually impairs light absorption in the semiconductor. Conversely, for ‘mesoscale’ contact widths > 1000 nm, the light interaction is determined by the geometric shadowing. We find that mesoscale silver contacts with triangular cross-section outperform other nanostructure morphologies in reducing shadow losses and yield contact transparency of >99% percent with sheet resistance <0.2 Ω/sq. Surprisingly, very densely spaced mesoscale silver triangular cross-section contacts can enhance the absorption of thin silicon/silver structures by up to 15% at a front contact coverage of 83%, due to light trapping by the front contact. Such structures can also maintain up to 100% absorption within the silicon, at a front contact coverage of 50%, relative to the same structure without metal.

Authors:

;

Publication Date:: 2018-03-06

Research Org.:: The Leland Stanford Junior Univ., Palo Alto, CA (United States)

Sponsoring Org.:: USDOE Office of Energy Efficiency and Renewable Energy (EERE)

OSTI Identifier:: 1423923

Alternate Identifier(s):: OSTI ID: 1503310

Grant/Contract Number:: EE0004946; EEC-1041895

Resource Type:: Published Article

Journal Name:: Optics Express

Additional Journal Information:: Journal Name: Optics Express Journal Volume: 26 Journal Issue: 6; Journal ID: ISSN 1094-4087

Publisher:: Optical Society of America

Country of Publication:: United States

Language:: English

Subject:: 14 SOLAR ENERGY; 36 MATERIALS SCIENCE; Solar energy; Micro-optics; Nanophotonics and photonic crystals

Citation Formats


                    Saive, Rebecca, and Atwater, Harry A. Mesoscale trumps nanoscale: metallic mesoscale contact morphology for improved light trapping, optical absorption and grid conductance in silicon solar cells.  United States: N. p., 2018. 
        Web.  doi:10.1364/OE.26.00A275.

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                    Saive, Rebecca, & Atwater, Harry A. Mesoscale trumps nanoscale: metallic mesoscale contact morphology for improved light trapping, optical absorption and grid conductance in silicon solar cells.  United States.  doi:10.1364/OE.26.00A275.

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                    Saive, Rebecca, and Atwater, Harry A. Tue .  
        "Mesoscale trumps nanoscale: metallic mesoscale contact morphology for improved light trapping, optical absorption and grid conductance in silicon solar cells".  United States.  doi:10.1364/OE.26.00A275.

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@article{osti_1423923,

  title        = {Mesoscale trumps nanoscale: metallic mesoscale contact morphology for improved light trapping, optical absorption and grid conductance in silicon solar cells},

  author       = {Saive, Rebecca and Atwater, Harry A.},

  abstractNote = {Here, we report on a computational study exploring the design of mesoscale metallic front contacts for solar cells. We investigated silver contact structures with circle, triangle and square cross-sections for various length scales and surface coverages. We found that for ‘nanoscale’ contacts with widths between 10 nm and 1000 nm, resonant coupling actually impairs light absorption in the semiconductor. Conversely, for ‘mesoscale’ contact widths > 1000 nm, the light interaction is determined by the geometric shadowing. We find that mesoscale silver contacts with triangular cross-section outperform other nanostructure morphologies in reducing shadow losses and yield contact transparency of >99% percent with sheet resistance <0.2 Ω/sq. Surprisingly, very densely spaced mesoscale silver triangular cross-section contacts can enhance the absorption of thin silicon/silver structures by up to 15% at a front contact coverage of 83%, due to light trapping by the front contact. Such structures can also maintain up to 100% absorption within the silicon, at a front contact coverage of 50%, relative to the same structure without metal.},

  doi          = {10.1364/OE.26.00A275},

  journal      = {Optics Express},

  number       = 6,

  volume       = 26,

  place        = {United States},

  year         = {2018},

  month        = {3}

}

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DOI: 10.1364/OE.26.00A275

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Figures / Tables:

Fig. 1: Schematic of the interaction of light with wave vector and metal structures of width w in the a) nanoscale (w<<λ), b) mesoscale (w ≥ λ) and c) macroscale (w>>λ).

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