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Title: Assessing the role of hydrogen in Fermi-level pinning in chalcopyrite and kesterite solar absorbers from first-principles calculations

Abstract

Understanding the impact of impurities in solar absorbers is critical to engineering high-performance in devices, particularly over extended periods of time. Here we use hybrid functional calculations to explore the role of hydrogen interstitial (H i) defects on the electronic properties of a number of attractive solar absorbers within the chalcopyrite and kesterite families to identify how this common impurity may influence device performance. Our results identify that H i can inhibit the highly p-type conditions desirable for several higher-band gap absorbers and that H incorporation could detrimentally affect the open-circuit voltage (V oc) and limit device efficiencies. Moreover, we discover that H i can drive the Fermi level away from the valence band edge enough to lead to n-type conductivity in a number of chalcopyrite and kesterite absorbers, particularly those containing Ag rather than Cu. We find these results can lead to interfacial Fermi-level pinning that can qualitatively explain observed performance in high-Ga content CIGSe solar cells that exhibit saturation in the V oc with increasing band gap. Our results suggest that compositional grading rather than bulk alloying, such as by creating In-rich surfaces, may be a better strategy to favorably engineering improved thin-film photovoltaics with larger-band gap absorbers.

Authors:
 [1];  [1];  [1];  [2];  [2];  [2]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. Univ. of Hawaii, Honolulu, HI (United States)
Publication Date:
Research Org.:
Univ. of Hawaii, Honolulu, HI (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Fuel Cell Technologies Office (EE-3F)
OSTI Identifier:
1570463
Grant/Contract Number:  
EE0006670; AC52-07NA27344
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 123; Journal Issue: 16; Journal ID: ISSN 0021-8979
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
08 HYDROGEN

Citation Formats

Varley, J. B., Lordi, V., Ogitsu, T., Deangelis, A., Horsley, K., and Gaillard, N. Assessing the role of hydrogen in Fermi-level pinning in chalcopyrite and kesterite solar absorbers from first-principles calculations. United States: N. p., 2018. Web. doi:10.1063/1.5006272.
Varley, J. B., Lordi, V., Ogitsu, T., Deangelis, A., Horsley, K., & Gaillard, N. Assessing the role of hydrogen in Fermi-level pinning in chalcopyrite and kesterite solar absorbers from first-principles calculations. United States. doi:10.1063/1.5006272.
Varley, J. B., Lordi, V., Ogitsu, T., Deangelis, A., Horsley, K., and Gaillard, N. Wed . "Assessing the role of hydrogen in Fermi-level pinning in chalcopyrite and kesterite solar absorbers from first-principles calculations". United States. doi:10.1063/1.5006272. https://www.osti.gov/servlets/purl/1570463.
@article{osti_1570463,
title = {Assessing the role of hydrogen in Fermi-level pinning in chalcopyrite and kesterite solar absorbers from first-principles calculations},
author = {Varley, J. B. and Lordi, V. and Ogitsu, T. and Deangelis, A. and Horsley, K. and Gaillard, N.},
abstractNote = {Understanding the impact of impurities in solar absorbers is critical to engineering high-performance in devices, particularly over extended periods of time. Here we use hybrid functional calculations to explore the role of hydrogen interstitial (Hi) defects on the electronic properties of a number of attractive solar absorbers within the chalcopyrite and kesterite families to identify how this common impurity may influence device performance. Our results identify that Hi can inhibit the highly p-type conditions desirable for several higher-band gap absorbers and that H incorporation could detrimentally affect the open-circuit voltage (Voc) and limit device efficiencies. Moreover, we discover that Hi can drive the Fermi level away from the valence band edge enough to lead to n-type conductivity in a number of chalcopyrite and kesterite absorbers, particularly those containing Ag rather than Cu. We find these results can lead to interfacial Fermi-level pinning that can qualitatively explain observed performance in high-Ga content CIGSe solar cells that exhibit saturation in the Voc with increasing band gap. Our results suggest that compositional grading rather than bulk alloying, such as by creating In-rich surfaces, may be a better strategy to favorably engineering improved thin-film photovoltaics with larger-band gap absorbers.},
doi = {10.1063/1.5006272},
journal = {Journal of Applied Physics},
number = 16,
volume = 123,
place = {United States},
year = {2018},
month = {3}
}

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