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Title: Controlling Metastable Native Point-Defect Populations in Cu(In,Ga)Se 2 and Cu 2ZnSnSe 4 Materials and Solar Cells through Voltage-Bias Annealing

Abstract

Our contribution describes the influence of low-temperature annealing with and without applied voltage bias on thin-film Cu 2ZnSnSe 4 (CZTSe), Cu(In,Ga)Se 2 (CIGS), and CdS material properties and solar cell performance. In order to quantify the effects of cation disorder on CZTSe device performance, completed devices were annealed under open-circuit conditions at various temperatures from 110 degrees C to 215 degrees C and subsequently quenched. Measurements on these devices document systematic, reversible changes in solar-cell performance consistent with a reduction in CZTSe band tails at lower annealing temperatures. CIGS and CZTSe solar cells were also annealed at various temperatures (200 degrees C for CIGS and 110 degrees C-215 degrees C for CZTSe) and subsequently quenched with continuously applied voltage bias to explore the effects of non-equilibrium annealing conditions. For both absorbers, large reversible changes in device characteristics correlated with the magnitude and sign of the applied voltage bias were observed. For CZTSe devices, the voltage-bias annealing (VBA) produced reversible changes in open-circuit voltage (VOC) from 289 meV to 446 meV. For CIGS solar cells, even larger changes were observed in device performance: photovoltaic (PV) conversion efficiency of the CIGS device varied from below 3% to above 15%, with corresponding changesmore » in CIGS hole density of about three orders of magnitude. Findings from these VBA experiments are interpreted in terms of changes to the metastable point-defect populations that control key properties in the absorber layers, and in the CdS buffer layer. Computational device modeling was performed to assess the impacts of cation disorder on the CZTSe VOC deficit, and to elucidate the effects of VBA treatments on metastable point defect populations in CZTSe, CIGS, and CdS. Our results indicate that band tails impose important limitations on CZTSe device performance. Device modeling results also indicate that non-equilibrium processing conditions including the effects of voltage bias can dramatically alter point-defect-mediated opto-electronic properties of semiconductors. Implications for optimization of PV materials and connections to long-term stability of PV devices are discussed.« less

Authors:
 [1];  [1];  [1]
  1. National Renewable Energy Lab. (NREL), Golden, CO (United States)
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S)
OSTI Identifier:
1343389
Alternate Identifier(s):
OSTI ID: 1361736
Report Number(s):
NREL/JA-5K00-66964
Journal ID: ISSN 0021-8979; TRN: US1700915
Grant/Contract Number:  
AC36-08GO28308
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 121; Journal Issue: 4; Journal ID: ISSN 0021-8979
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; solar cells; II-VI semiconductors; carrier density; materials properties; point defects

Citation Formats

Teeter, Glenn, Harvey, Steve P., and Johnston, Steve. Controlling Metastable Native Point-Defect Populations in Cu(In,Ga)Se2 and Cu2ZnSnSe4 Materials and Solar Cells through Voltage-Bias Annealing. United States: N. p., 2017. Web. doi:10.1063/1.4973959.
Teeter, Glenn, Harvey, Steve P., & Johnston, Steve. Controlling Metastable Native Point-Defect Populations in Cu(In,Ga)Se2 and Cu2ZnSnSe4 Materials and Solar Cells through Voltage-Bias Annealing. United States. doi:10.1063/1.4973959.
Teeter, Glenn, Harvey, Steve P., and Johnston, Steve. Mon . "Controlling Metastable Native Point-Defect Populations in Cu(In,Ga)Se2 and Cu2ZnSnSe4 Materials and Solar Cells through Voltage-Bias Annealing". United States. doi:10.1063/1.4973959. https://www.osti.gov/servlets/purl/1343389.
@article{osti_1343389,
title = {Controlling Metastable Native Point-Defect Populations in Cu(In,Ga)Se2 and Cu2ZnSnSe4 Materials and Solar Cells through Voltage-Bias Annealing},
author = {Teeter, Glenn and Harvey, Steve P. and Johnston, Steve},
abstractNote = {Our contribution describes the influence of low-temperature annealing with and without applied voltage bias on thin-film Cu2ZnSnSe4 (CZTSe), Cu(In,Ga)Se2 (CIGS), and CdS material properties and solar cell performance. In order to quantify the effects of cation disorder on CZTSe device performance, completed devices were annealed under open-circuit conditions at various temperatures from 110 degrees C to 215 degrees C and subsequently quenched. Measurements on these devices document systematic, reversible changes in solar-cell performance consistent with a reduction in CZTSe band tails at lower annealing temperatures. CIGS and CZTSe solar cells were also annealed at various temperatures (200 degrees C for CIGS and 110 degrees C-215 degrees C for CZTSe) and subsequently quenched with continuously applied voltage bias to explore the effects of non-equilibrium annealing conditions. For both absorbers, large reversible changes in device characteristics correlated with the magnitude and sign of the applied voltage bias were observed. For CZTSe devices, the voltage-bias annealing (VBA) produced reversible changes in open-circuit voltage (VOC) from 289 meV to 446 meV. For CIGS solar cells, even larger changes were observed in device performance: photovoltaic (PV) conversion efficiency of the CIGS device varied from below 3% to above 15%, with corresponding changes in CIGS hole density of about three orders of magnitude. Findings from these VBA experiments are interpreted in terms of changes to the metastable point-defect populations that control key properties in the absorber layers, and in the CdS buffer layer. Computational device modeling was performed to assess the impacts of cation disorder on the CZTSe VOC deficit, and to elucidate the effects of VBA treatments on metastable point defect populations in CZTSe, CIGS, and CdS. Our results indicate that band tails impose important limitations on CZTSe device performance. Device modeling results also indicate that non-equilibrium processing conditions including the effects of voltage bias can dramatically alter point-defect-mediated opto-electronic properties of semiconductors. Implications for optimization of PV materials and connections to long-term stability of PV devices are discussed.},
doi = {10.1063/1.4973959},
journal = {Journal of Applied Physics},
number = 4,
volume = 121,
place = {United States},
year = {Mon Jan 30 00:00:00 EST 2017},
month = {Mon Jan 30 00:00:00 EST 2017}
}

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Works referenced in this record:

Defect physics of the kesterite thin-film solar cell absorber Cu2ZnSnS4
journal, January 2010

  • Chen, Shiyou; Gong, X. G.; Walsh, Aron
  • Applied Physics Letters, Vol. 96, Issue 2, Article No. 021902
  • DOI: 10.1063/1.3275796

Development of CZTS-based thin film solar cells
journal, February 2009

  • Katagiri, Hironori; Jimbo, Kazuo; Maw, Win Shwe
  • Thin Solid Films, Vol. 517, Issue 7, p. 2455-2460
  • DOI: 10.1016/j.tsf.2008.11.002

Detailed Balance Limit of Efficiency of p‐n Junction Solar Cells
journal, March 1961

  • Shockley, William; Queisser, Hans J.
  • Journal of Applied Physics, Vol. 32, Issue 3, p. 510-519
  • DOI: 10.1063/1.1736034