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Title: Solubility and Diffusivity: Important Metrics in the Search for the Root Cause of Light- and Elevated Temperature-Induced Degradation

Light- and elevated temperature-induced degradation (LeTID) is a detrimental effect observed under operating conditions in p-type multicrystalline silicon (mc-Si) solar cells. In this paper, we employ synchrotron-based techniques to study the dissolution of precipitates due to different firing processes at grain boundaries in LeTID-affected mc-Si. The synchrotron measurements show clear dissolution of collocated metal precipitates during firing. We compare our observations with degradation behavior in the same wafers. The experimental results are complemented with process simulations to provide insight into the change in bulk point defect concentration due to firing. Several studies have proposed that LeTID is caused by metal-rich precipitate dissolution during contact firing, and we find that the solubility and diffusivity are promising screening metrics to identify metals that are compatible with this hypothesis. While slower and less soluble elements (e.g., Fe and Cr) are not compatible according to our simulations, the point defect concentrations of faster and more soluble elements (e.g., Cu and Ni) increase after a high-temperature firing process, primarily due to emitter segregation rather than precipitate dissolution. Finally, these results are a useful complement to lifetime spectroscopy techniques, and can be used to evaluate additional candidates in the search for the root cause of LeTID.
Authors:
ORCiD logo [1] ; ORCiD logo [1] ;  [2] ; ORCiD logo [2] ; ORCiD logo [3] ;  [4] ;  [4] ; ORCiD logo [1] ;  [1] ;  [1] ; ORCiD logo [1] ;  [1] ;  [1] ;  [3] ;  [2] ; ORCiD logo [1]
  1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
  2. Solar Energy Research Inst. of Singapore (Singapore)
  3. Aalto Univ., Espoo (Finland). Dept. of Electronics and Nanoengineering
  4. Argonne National Lab. (ANL), Argonne, IL (United States)
Publication Date:
Grant/Contract Number:
AC02-06CH11357; ECS-0335765; CA EEC-1041895; 1122374; 307315
Type:
Accepted Manuscript
Journal Name:
IEEE Journal of Photovoltaics
Additional Journal Information:
Journal Volume: 8; Journal Issue: 2; Journal ID: ISSN 2156-3381
Publisher:
IEEE
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States); Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Aalto Univ., Espoo (Finland)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF); European Research Council (ERC)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; carrier-induced degradation (CID); light- and elevated temperature-induced degradation (LeTID); light-induced degradation; materials reliability; multicrystalline silicon (mc-Si); passivated emitter and rear cell (PERC); synchrotron; silicon; X-ray fluorescence
OSTI Identifier:
1437374

Jensen, Mallory A., Morishige, Ashley E., Chakraborty, Sagnik, Sharma, Romika, Laine, Hannu S., Lai, Barry, Rose, Volker, Youssef, Amanda, Looney, Erin E., Wieghold, Sarah, Poindexter, Jeremy R., Correa-Baena, Juan-Pablo, Felisca, Tahina, Savin, Hele, Li, Joel B., and Buonassisi, Tonio. Solubility and Diffusivity: Important Metrics in the Search for the Root Cause of Light- and Elevated Temperature-Induced Degradation. United States: N. p., Web. doi:10.1109/jphotov.2018.2791411.
Jensen, Mallory A., Morishige, Ashley E., Chakraborty, Sagnik, Sharma, Romika, Laine, Hannu S., Lai, Barry, Rose, Volker, Youssef, Amanda, Looney, Erin E., Wieghold, Sarah, Poindexter, Jeremy R., Correa-Baena, Juan-Pablo, Felisca, Tahina, Savin, Hele, Li, Joel B., & Buonassisi, Tonio. Solubility and Diffusivity: Important Metrics in the Search for the Root Cause of Light- and Elevated Temperature-Induced Degradation. United States. doi:10.1109/jphotov.2018.2791411.
Jensen, Mallory A., Morishige, Ashley E., Chakraborty, Sagnik, Sharma, Romika, Laine, Hannu S., Lai, Barry, Rose, Volker, Youssef, Amanda, Looney, Erin E., Wieghold, Sarah, Poindexter, Jeremy R., Correa-Baena, Juan-Pablo, Felisca, Tahina, Savin, Hele, Li, Joel B., and Buonassisi, Tonio. 2018. "Solubility and Diffusivity: Important Metrics in the Search for the Root Cause of Light- and Elevated Temperature-Induced Degradation". United States. doi:10.1109/jphotov.2018.2791411.
@article{osti_1437374,
title = {Solubility and Diffusivity: Important Metrics in the Search for the Root Cause of Light- and Elevated Temperature-Induced Degradation},
author = {Jensen, Mallory A. and Morishige, Ashley E. and Chakraborty, Sagnik and Sharma, Romika and Laine, Hannu S. and Lai, Barry and Rose, Volker and Youssef, Amanda and Looney, Erin E. and Wieghold, Sarah and Poindexter, Jeremy R. and Correa-Baena, Juan-Pablo and Felisca, Tahina and Savin, Hele and Li, Joel B. and Buonassisi, Tonio},
abstractNote = {Light- and elevated temperature-induced degradation (LeTID) is a detrimental effect observed under operating conditions in p-type multicrystalline silicon (mc-Si) solar cells. In this paper, we employ synchrotron-based techniques to study the dissolution of precipitates due to different firing processes at grain boundaries in LeTID-affected mc-Si. The synchrotron measurements show clear dissolution of collocated metal precipitates during firing. We compare our observations with degradation behavior in the same wafers. The experimental results are complemented with process simulations to provide insight into the change in bulk point defect concentration due to firing. Several studies have proposed that LeTID is caused by metal-rich precipitate dissolution during contact firing, and we find that the solubility and diffusivity are promising screening metrics to identify metals that are compatible with this hypothesis. While slower and less soluble elements (e.g., Fe and Cr) are not compatible according to our simulations, the point defect concentrations of faster and more soluble elements (e.g., Cu and Ni) increase after a high-temperature firing process, primarily due to emitter segregation rather than precipitate dissolution. Finally, these results are a useful complement to lifetime spectroscopy techniques, and can be used to evaluate additional candidates in the search for the root cause of LeTID.},
doi = {10.1109/jphotov.2018.2791411},
journal = {IEEE Journal of Photovoltaics},
number = 2,
volume = 8,
place = {United States},
year = {2018},
month = {2}
}