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Title: Investigating PID shunting in polycrystalline silicon modules via multiscale, multitechnique characterization

Abstract

We investigated the potential-induced degradation (PID) shunting mechanism in multicrystalline-silicon photovoltaic modules by using a multiscale, multitechnique characterization approach. Both field-stressed modules and laboratory-stressed mini modules were studied. We used photoluminescence, electroluminescence, and dark lock-in thermography imaging to identify degraded areas at the module scale. Small samples were then removed from degraded areas, laser marked, and imaged by scanning electron microscopy. We used simultaneous electron-beam induced current imaging and focused ion beam milling to mark around PID shunts for chemical analysis by time-of-flight secondary-ion mass spectrometry or to isolate individual shunt defects for transmission electron microscopy and atom-probe tomography analysis. By spanning a range of 10 orders of magnitude in size, this approach enabled us to investigate the root-cause mechanisms for PID shunting. We observed a direct correlation between recombination active shunts and sodium content. The sodium content in shunted areas peaks at the SiNX/Si interface and is consistently observed at a concentration of 0.1% to 2% in shunted areas. Analysis of samples subjected to PID recovery, either activated by electron beam or thermal effects only, reveals that recovery of isolated shunts correlates with diffusion of sodium out of the structural defects to the silicon surface. We observed the rolemore » of oxygen and chlorine in PID shunting and found that those species - although sometimes present in structural defects where PID shunting was observed - do not play a consistent role in PID shunting.« less

Authors:
ORCiD logo [1];  [1]; ORCiD logo [1];  [2];  [2];  [1];  [1];  [1]
  1. National Renewable Energy Lab. (NREL), Golden, CO (United States)
  2. Colorado School of Mines, 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:
1427356
Alternate Identifier(s):
OSTI ID: 1436888
Report Number(s):
NREL/JA-5K00-70168
Journal ID: ISSN 1062-7995
Grant/Contract Number:  
AC36-08GO28308
Resource Type:
Accepted Manuscript
Journal Name:
Progress in Photovoltaics
Additional Journal Information:
Journal Name: Progress in Photovoltaics; Journal ID: ISSN 1062-7995
Publisher:
Wiley
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 42 ENGINEERING; PID; TOF-SIMS; EBIC; polysilicon; reliability

Citation Formats

Harvey, Steven P., Moseley, John, Norman, Andrew, Stokes, Adam, Gorman, Brian, Hacke, Peter, Johnston, Steve, and Al-Jassim, Mowafak. Investigating PID shunting in polycrystalline silicon modules via multiscale, multitechnique characterization. United States: N. p., 2018. Web. doi:10.1002/pip.2996.
Harvey, Steven P., Moseley, John, Norman, Andrew, Stokes, Adam, Gorman, Brian, Hacke, Peter, Johnston, Steve, & Al-Jassim, Mowafak. Investigating PID shunting in polycrystalline silicon modules via multiscale, multitechnique characterization. United States. doi:10.1002/pip.2996.
Harvey, Steven P., Moseley, John, Norman, Andrew, Stokes, Adam, Gorman, Brian, Hacke, Peter, Johnston, Steve, and Al-Jassim, Mowafak. Tue . "Investigating PID shunting in polycrystalline silicon modules via multiscale, multitechnique characterization". United States. doi:10.1002/pip.2996. https://www.osti.gov/servlets/purl/1427356.
@article{osti_1427356,
title = {Investigating PID shunting in polycrystalline silicon modules via multiscale, multitechnique characterization},
author = {Harvey, Steven P. and Moseley, John and Norman, Andrew and Stokes, Adam and Gorman, Brian and Hacke, Peter and Johnston, Steve and Al-Jassim, Mowafak},
abstractNote = {We investigated the potential-induced degradation (PID) shunting mechanism in multicrystalline-silicon photovoltaic modules by using a multiscale, multitechnique characterization approach. Both field-stressed modules and laboratory-stressed mini modules were studied. We used photoluminescence, electroluminescence, and dark lock-in thermography imaging to identify degraded areas at the module scale. Small samples were then removed from degraded areas, laser marked, and imaged by scanning electron microscopy. We used simultaneous electron-beam induced current imaging and focused ion beam milling to mark around PID shunts for chemical analysis by time-of-flight secondary-ion mass spectrometry or to isolate individual shunt defects for transmission electron microscopy and atom-probe tomography analysis. By spanning a range of 10 orders of magnitude in size, this approach enabled us to investigate the root-cause mechanisms for PID shunting. We observed a direct correlation between recombination active shunts and sodium content. The sodium content in shunted areas peaks at the SiNX/Si interface and is consistently observed at a concentration of 0.1% to 2% in shunted areas. Analysis of samples subjected to PID recovery, either activated by electron beam or thermal effects only, reveals that recovery of isolated shunts correlates with diffusion of sodium out of the structural defects to the silicon surface. We observed the role of oxygen and chlorine in PID shunting and found that those species - although sometimes present in structural defects where PID shunting was observed - do not play a consistent role in PID shunting.},
doi = {10.1002/pip.2996},
journal = {Progress in Photovoltaics},
number = ,
volume = ,
place = {United States},
year = {2018},
month = {2}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Figures / Tables:

FIGURE 1 FIGURE 1: A, Dark lock‐in thermography (DLIT) image of entire module (1‐2 m). B, DLIT image of a single cell from the module. C, High‐resolution DLIT of shunted area; the black circles show the location of laser marks around shunted area. D, Focused ion beam (FIB) marks were put aroundmore » single shunt identified with electron‐beam induced current (EBIC). E, Time‐of‐flight secondary‐ion mass spectrometry (TOF‐SIMS) image (200‐ 200 μm), showing the Ga signal in red (corresponds to FIB marks), and sodium in green. The sodium spot matches the location of the shunt seen in EBIC. F, TOF‐SIMS 3D rendering of the shunt area. A single shunt is seen to persist through the depth of the measurement. G, Selected‐area depth profiles from the shunted and unshunted regions, marked with circles in D. The sodium concentration peaks at ~1% at the SiN/Si interface in the shunted region, identified with the dashed line [Colour figure can be viewed at wileyonlinelibrary.com]« less

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    Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.