SnO2-Catalyzed Oxidation in High-Efficiency CdTe Solar Cells

Perkins, Craig; McGott, Deborah L; Reese, Matthew O; Metzger, Wyatt K

doi:10.1021/acsami.9b00835

Title: SnO₂-Catalyzed Oxidation in High-Efficiency CdTe Solar Cells

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Abstract

Interfaces at the front of superstrate CdTe-based solar cells are critical to carrier transport, recombination, and device performance, yet determination of the chemical structure of these nanoscale regions has remained elusive. This is partly due to changes that occur at the front interfaces during high temperature growth and substantive changes occurring during postdeposition processing. In addition, these buried interfaces are extremely difficult to access in a way that preserves chemical information. In this work, we use a recently developed thermomechanical cleaving technique paired with X-ray photoelectron spectroscopy to probe oxidation states at the SnO₂ interface of CdTe solar cells. We show that the tin oxide front electrode promotes the formation of nanometer-scale oxides of tellurium and sulfur. Most oxidation occurs during CdCl₂/O₂ activation. Surprisingly, we show that relatively low-temperature anneals (180-260 degrees C) used to diffuse and activate copper acceptors in a doping/back contact process also cause significant changes in oxidation at the front of the cell, providing a heretofore missing aspect of how back contact processes can modify device transport, recombination, and performance. Device performance is shown to correlate with the extent of tellurium and sulfur oxidation within this nanometer-scale region. Mechanisms responsible for these beneficial effects are proposed.

Authors:

^[1]; McGott, Deborah L ^[1];

^[1]; Metzger, Wyatt K ^[1]

National Renewable Energy Lab. (NREL), Golden, CO (United States)

Publication Date:: Fri Mar 08 00:00:00 EST 2019

Research Org.:: National Renewable Energy Lab. (NREL), Golden, CO (United States)

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

OSTI Identifier:: 1513192

Report Number(s):: NREL/JA-5K00-73453
Journal ID: ISSN 1944-8244

Grant/Contract Number:: AC36-08GO28308

Resource Type:: Accepted Manuscript

Journal Name:: ACS Applied Materials and Interfaces

Additional Journal Information:: Journal Volume: 11; Journal Issue: 13; Journal ID: ISSN 1944-8244

Publisher:: American Chemical Society (ACS)

Country of Publication:: United States

Language:: English

Subject:: 14 SOLAR ENERGY; 36 MATERIALS SCIENCE; cadmium telluride; interfaces; passivation; photovoltaics; solar cells; tin oxide; X-ray photoelectron spectroscopy

Citation Formats


                    Perkins, Craig, McGott, Deborah L, Reese, Matthew O, and Metzger, Wyatt K. SnO2-Catalyzed Oxidation in High-Efficiency CdTe Solar Cells.  United States: N. p., 2019. 
Web.  doi:10.1021/acsami.9b00835.

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                    Perkins, Craig, McGott, Deborah L, Reese, Matthew O, & Metzger, Wyatt K. SnO2-Catalyzed Oxidation in High-Efficiency CdTe Solar Cells.  United States.  https://doi.org/10.1021/acsami.9b00835

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                    Perkins, Craig, McGott, Deborah L, Reese, Matthew O, and Metzger, Wyatt K. Fri .  
"SnO2-Catalyzed Oxidation in High-Efficiency CdTe Solar Cells".  United States.  https://doi.org/10.1021/acsami.9b00835.  https://www.osti.gov/servlets/purl/1513192.

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@article{osti_1513192,

  title        = {SnO2-Catalyzed Oxidation in High-Efficiency CdTe Solar Cells},

  author       = {Perkins, Craig and McGott, Deborah L and Reese, Matthew O and Metzger, Wyatt K},

  abstractNote = {Interfaces at the front of superstrate CdTe-based solar cells are critical to carrier transport, recombination, and device performance, yet determination of the chemical structure of these nanoscale regions has remained elusive. This is partly due to changes that occur at the front interfaces during high temperature growth and substantive changes occurring during postdeposition processing. In addition, these buried interfaces are extremely difficult to access in a way that preserves chemical information. In this work, we use a recently developed thermomechanical cleaving technique paired with X-ray photoelectron spectroscopy to probe oxidation states at the SnO2 interface of CdTe solar cells. We show that the tin oxide front electrode promotes the formation of nanometer-scale oxides of tellurium and sulfur. Most oxidation occurs during CdCl2/O2 activation. Surprisingly, we show that relatively low-temperature anneals (180-260 degrees C) used to diffuse and activate copper acceptors in a doping/back contact process also cause significant changes in oxidation at the front of the cell, providing a heretofore missing aspect of how back contact processes can modify device transport, recombination, and performance. Device performance is shown to correlate with the extent of tellurium and sulfur oxidation within this nanometer-scale region. Mechanisms responsible for these beneficial effects are proposed.},

  doi          = {10.1021/acsami.9b00835},

  journal      = {ACS Applied Materials and Interfaces},

  number       = 13,

  volume       = 11,

  place        = {United States},

  year         = {Fri Mar 08 00:00:00 EST 2019},

  month        = {Fri Mar 08 00:00:00 EST 2019}

}

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Title: SnO2-Catalyzed Oxidation in High-Efficiency CdTe Solar Cells

Abstract

Citation Formats

Title: SnO₂-Catalyzed Oxidation in High-Efficiency CdTe Solar Cells