Lithium Fluoride Based Electron Contacts for High Efficiency n-Type Crystalline Silicon Solar Cells

James Bullock; Peiting Zheng; Quentin Jeangros; Mahmut Tosun; Mark Hettick; Carolin M. Sutter-Fella; Yimao Wan; Thomas Allen; Di Yan; Daniel Macdonald; Stefaan De Wolf; Aïcha Hessler-Wyser; Andres Cuevas; Ali Javey

doi:10.1002/aenm.201600241

Lithium Fluoride Based Electron Contacts for High Efficiency n-Type Crystalline Silicon Solar Cells

James Bullock, Peiting Zheng, Quentin Jeangros, Mahmut Tosun, Mark Hettick, Carolin M. Sutter-Fella, Yimao Wan, Thomas Allen, Di Yan, Daniel Macdonald, Stefaan De Wolf, Aïcha Hessler-Wyser, Andres Cuevas^*, Ali Javey

^*Corresponding author for this work

Physical Sciences and Engineering

Research output: Contribution to journal › Article › peer-review

119 Scopus citations

Abstract

Low-resistance contact to lightly doped n-type crystalline silicon (c-Si) has long been recognized as technologically challenging due to the pervasive Fermi-level pinning effect. This has hindered the development of certain devices such as n-type c-Si solar cells made with partial rear contacts (PRC) directly to the lowly doped c-Si wafer. Here, a simple and robust process is demonstrated for achieving mΩ cm² scale contact resistivities on lightly doped n-type c-Si via a lithium fluoride/aluminum contact. The realization of this low-resistance contact enables the fabrication of a first-of-its-kind high-efficiency n-type PRC solar cell. The electron contact of this cell is made to less than 1% of the rear surface area, reducing the impact of contact recombination and optical losses, permitting a power conversion efficiency of greater than 20% in the initial proof-of-concept stage. The implementation of the LiF_x/Al contact mitigates the need for the costly high-temperature phosphorus diffusion, typically implemented in such a cell design to nullify the issue of Fermi level pinning at the electron contact. The timing of this demonstration is significant, given the ongoing transition from p-type to n-type c-Si solar cell architectures, together with the increased adoption of advanced PRC device structures within the c-Si photovoltaic industry.

Original language	English (US)
Article number	1600241
Journal	Advanced Energy Materials
Volume	6
Issue number	14
DOIs	https://doi.org/10.1002/aenm.201600241
State	Published - Jul 20 2016

Bibliographical note

Funding Information:
J.B. and P.Z. contributed equally to this work. Device design, fabrication, and characterization were funded by the Bay Area Photovoltaics Consortium (BAPVC) and the Australian Renewable Energy Agency (ARENA). Materials characterization was supported by the Electronic Materials Programs, funded by the Director, Office of Science, Office of Basic Energy Sciences, Material Sciences and Engineering Division of the U.S. Department of Energy under (Contract No. DE-AC02-05CH11231). Work at the Molecular Foundry was supported by the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Work at EPFL was supported by the Office Fedéral de l'Energie (OFEN) and the Interdisciplinary Centre for Electron Microscopy (CIME) of EPFL is acknowledged for access to their electron microscopes. C.M.S.-F. acknowledges financial support from the Swiss National Science Foundation (P2EZP2_155586).

Publisher Copyright:
© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Keywords

contacts
fermi levels
lithium fluoride
photovoltaics
silicon solar cells

ASJC Scopus subject areas

Renewable Energy, Sustainability and the Environment
Materials Science(all)

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

Access to Document

10.1002/aenm.201600241

Cite this

Bullock, J., Zheng, P., Jeangros, Q., Tosun, M., Hettick, M., Sutter-Fella, C. M., Wan, Y., Allen, T., Yan, D., Macdonald, D., De Wolf, S., Hessler-Wyser, A., Cuevas, A., & Javey, A. (2016). Lithium Fluoride Based Electron Contacts for High Efficiency n-Type Crystalline Silicon Solar Cells. Advanced Energy Materials, 6(14), [1600241]. https://doi.org/10.1002/aenm.201600241

@article{9b36ee3177b14cf0a99ebbb148e95e98,

title = "Lithium Fluoride Based Electron Contacts for High Efficiency n-Type Crystalline Silicon Solar Cells",

abstract = "Low-resistance contact to lightly doped n-type crystalline silicon (c-Si) has long been recognized as technologically challenging due to the pervasive Fermi-level pinning effect. This has hindered the development of certain devices such as n-type c-Si solar cells made with partial rear contacts (PRC) directly to the lowly doped c-Si wafer. Here, a simple and robust process is demonstrated for achieving mΩ cm2 scale contact resistivities on lightly doped n-type c-Si via a lithium fluoride/aluminum contact. The realization of this low-resistance contact enables the fabrication of a first-of-its-kind high-efficiency n-type PRC solar cell. The electron contact of this cell is made to less than 1% of the rear surface area, reducing the impact of contact recombination and optical losses, permitting a power conversion efficiency of greater than 20% in the initial proof-of-concept stage. The implementation of the LiFx/Al contact mitigates the need for the costly high-temperature phosphorus diffusion, typically implemented in such a cell design to nullify the issue of Fermi level pinning at the electron contact. The timing of this demonstration is significant, given the ongoing transition from p-type to n-type c-Si solar cell architectures, together with the increased adoption of advanced PRC device structures within the c-Si photovoltaic industry.",

keywords = "contacts, fermi levels, lithium fluoride, photovoltaics, silicon solar cells",

author = "James Bullock and Peiting Zheng and Quentin Jeangros and Mahmut Tosun and Mark Hettick and Sutter-Fella, {Carolin M.} and Yimao Wan and Thomas Allen and Di Yan and Daniel Macdonald and {De Wolf}, Stefaan and A{\"i}cha Hessler-Wyser and Andres Cuevas and Ali Javey",

note = "Funding Information: J.B. and P.Z. contributed equally to this work. Device design, fabrication, and characterization were funded by the Bay Area Photovoltaics Consortium (BAPVC) and the Australian Renewable Energy Agency (ARENA). Materials characterization was supported by the Electronic Materials Programs, funded by the Director, Office of Science, Office of Basic Energy Sciences, Material Sciences and Engineering Division of the U.S. Department of Energy under (Contract No. DE-AC02-05CH11231). Work at the Molecular Foundry was supported by the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Work at EPFL was supported by the Office Fed{\'e}ral de l'Energie (OFEN) and the Interdisciplinary Centre for Electron Microscopy (CIME) of EPFL is acknowledged for access to their electron microscopes. C.M.S.-F. acknowledges financial support from the Swiss National Science Foundation (P2EZP2_155586). Publisher Copyright: {\textcopyright} 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim",

year = "2016",

month = jul,

day = "20",

doi = "10.1002/aenm.201600241",

language = "English (US)",

volume = "6",

journal = "Advanced Energy Materials",

issn = "1614-6832",

publisher = "Wiley-VCH Verlag",

number = "14",

}

TY - JOUR

T1 - Lithium Fluoride Based Electron Contacts for High Efficiency n-Type Crystalline Silicon Solar Cells

AU - Bullock, James

AU - Zheng, Peiting

AU - Jeangros, Quentin

AU - Tosun, Mahmut

AU - Hettick, Mark

AU - Sutter-Fella, Carolin M.

AU - Wan, Yimao

AU - Allen, Thomas

AU - Yan, Di

AU - Macdonald, Daniel

AU - De Wolf, Stefaan

AU - Hessler-Wyser, Aïcha

AU - Cuevas, Andres

AU - Javey, Ali

N1 - Funding Information: J.B. and P.Z. contributed equally to this work. Device design, fabrication, and characterization were funded by the Bay Area Photovoltaics Consortium (BAPVC) and the Australian Renewable Energy Agency (ARENA). Materials characterization was supported by the Electronic Materials Programs, funded by the Director, Office of Science, Office of Basic Energy Sciences, Material Sciences and Engineering Division of the U.S. Department of Energy under (Contract No. DE-AC02-05CH11231). Work at the Molecular Foundry was supported by the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Work at EPFL was supported by the Office Fedéral de l'Energie (OFEN) and the Interdisciplinary Centre for Electron Microscopy (CIME) of EPFL is acknowledged for access to their electron microscopes. C.M.S.-F. acknowledges financial support from the Swiss National Science Foundation (P2EZP2_155586). Publisher Copyright: © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

PY - 2016/7/20

Y1 - 2016/7/20

N2 - Low-resistance contact to lightly doped n-type crystalline silicon (c-Si) has long been recognized as technologically challenging due to the pervasive Fermi-level pinning effect. This has hindered the development of certain devices such as n-type c-Si solar cells made with partial rear contacts (PRC) directly to the lowly doped c-Si wafer. Here, a simple and robust process is demonstrated for achieving mΩ cm2 scale contact resistivities on lightly doped n-type c-Si via a lithium fluoride/aluminum contact. The realization of this low-resistance contact enables the fabrication of a first-of-its-kind high-efficiency n-type PRC solar cell. The electron contact of this cell is made to less than 1% of the rear surface area, reducing the impact of contact recombination and optical losses, permitting a power conversion efficiency of greater than 20% in the initial proof-of-concept stage. The implementation of the LiFx/Al contact mitigates the need for the costly high-temperature phosphorus diffusion, typically implemented in such a cell design to nullify the issue of Fermi level pinning at the electron contact. The timing of this demonstration is significant, given the ongoing transition from p-type to n-type c-Si solar cell architectures, together with the increased adoption of advanced PRC device structures within the c-Si photovoltaic industry.

AB - Low-resistance contact to lightly doped n-type crystalline silicon (c-Si) has long been recognized as technologically challenging due to the pervasive Fermi-level pinning effect. This has hindered the development of certain devices such as n-type c-Si solar cells made with partial rear contacts (PRC) directly to the lowly doped c-Si wafer. Here, a simple and robust process is demonstrated for achieving mΩ cm2 scale contact resistivities on lightly doped n-type c-Si via a lithium fluoride/aluminum contact. The realization of this low-resistance contact enables the fabrication of a first-of-its-kind high-efficiency n-type PRC solar cell. The electron contact of this cell is made to less than 1% of the rear surface area, reducing the impact of contact recombination and optical losses, permitting a power conversion efficiency of greater than 20% in the initial proof-of-concept stage. The implementation of the LiFx/Al contact mitigates the need for the costly high-temperature phosphorus diffusion, typically implemented in such a cell design to nullify the issue of Fermi level pinning at the electron contact. The timing of this demonstration is significant, given the ongoing transition from p-type to n-type c-Si solar cell architectures, together with the increased adoption of advanced PRC device structures within the c-Si photovoltaic industry.

KW - contacts

KW - fermi levels

KW - lithium fluoride

KW - photovoltaics

KW - silicon solar cells

UR - http://www.scopus.com/inward/record.url?scp=84971351202&partnerID=8YFLogxK

U2 - 10.1002/aenm.201600241

DO - 10.1002/aenm.201600241

M3 - Article

AN - SCOPUS:84971351202

SN - 1614-6832

VL - 6

JO - Advanced Energy Materials

JF - Advanced Energy Materials

IS - 14

M1 - 1600241

ER -

Lithium Fluoride Based Electron Contacts for High Efficiency n-Type Crystalline Silicon Solar Cells

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

UN SDGs

Access to Document

Other files and links

Fingerprint

Cite this