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Title: Transmission Electron Microscopy Study on Microstructure of Degraded CdTe Modules

Abstract

In this paper, we employ transmission electron microscopy coupled with energy-dispersive X-ray spectrometry (EDS) to study the structure and chemistry of cadmium telluride (CdTe) thin-film solar cells with different extents of degradation. The studied regions originate from the same photovoltaic mini-module, which was subjected to one-sun light exposure at a temperature of 100 degrees C for 400 h to induce light and heat degradation. EDS maps reveal a discontinuous CdS layer and particles rich in O and S but Te-depleted within the CdTe absorber layer after the light and heat stress. These features could act as enhanced recombination centers, resulting in decreased photovoltaic conversion efficiency. Additionally, the most degraded CdTe sample shows a strong accumulation of Na precisely localized in the discontinuous part of the CdS layer. The local Na concentration is determined to be ~16 at.%. In addition, appreciable Na accumulation is observed at the soda-lime glass/transparent conductive oxide interface in both degraded CdTe solar cells. The microstructure of the baseline CdTe mini-module with no stress was also investigated to demonstrate that the structure difference was caused by the light- and heat-induced degradation, instead of module fabrication. These results highlight the need to control the distribution of Na inmore » fielded CdTe modules to sustain long-term high-power output.« less

Authors:
 [1];  [1];  [1];  [1];  [1];  [1];  [1]
  1. National Renewable Energy Laboratory (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:
1514846
Report Number(s):
NREL/JA-5K00-72663
Grant/Contract Number:  
AC36-08GO28308
Resource Type:
Accepted Manuscript
Journal Name:
IEEE Journal of Photovoltaics
Additional Journal Information:
Journal Volume: 9; Journal Issue: 3
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 36 MATERIALS SCIENCE; cadmium telluride mini-modules; CdTe; energy-dispersive X-ray spectrometry; light-induced degradation; heat-induced degradation; Na accumulation; diffusion; transmission electron microscopy

Citation Formats

Liu, Jun, Johnston, Steven, Guthrey, Harvey L, Albin, David S, Hacke, Peter L, Pan, Jie, and Al-Jassim, Mowafak M. Transmission Electron Microscopy Study on Microstructure of Degraded CdTe Modules. United States: N. p., 2019. Web. doi:10.1109/JPHOTOV.2019.2893854.
Liu, Jun, Johnston, Steven, Guthrey, Harvey L, Albin, David S, Hacke, Peter L, Pan, Jie, & Al-Jassim, Mowafak M. Transmission Electron Microscopy Study on Microstructure of Degraded CdTe Modules. United States. doi:10.1109/JPHOTOV.2019.2893854.
Liu, Jun, Johnston, Steven, Guthrey, Harvey L, Albin, David S, Hacke, Peter L, Pan, Jie, and Al-Jassim, Mowafak M. Mon . "Transmission Electron Microscopy Study on Microstructure of Degraded CdTe Modules". United States. doi:10.1109/JPHOTOV.2019.2893854.
@article{osti_1514846,
title = {Transmission Electron Microscopy Study on Microstructure of Degraded CdTe Modules},
author = {Liu, Jun and Johnston, Steven and Guthrey, Harvey L and Albin, David S and Hacke, Peter L and Pan, Jie and Al-Jassim, Mowafak M},
abstractNote = {In this paper, we employ transmission electron microscopy coupled with energy-dispersive X-ray spectrometry (EDS) to study the structure and chemistry of cadmium telluride (CdTe) thin-film solar cells with different extents of degradation. The studied regions originate from the same photovoltaic mini-module, which was subjected to one-sun light exposure at a temperature of 100 degrees C for 400 h to induce light and heat degradation. EDS maps reveal a discontinuous CdS layer and particles rich in O and S but Te-depleted within the CdTe absorber layer after the light and heat stress. These features could act as enhanced recombination centers, resulting in decreased photovoltaic conversion efficiency. Additionally, the most degraded CdTe sample shows a strong accumulation of Na precisely localized in the discontinuous part of the CdS layer. The local Na concentration is determined to be ~16 at.%. In addition, appreciable Na accumulation is observed at the soda-lime glass/transparent conductive oxide interface in both degraded CdTe solar cells. The microstructure of the baseline CdTe mini-module with no stress was also investigated to demonstrate that the structure difference was caused by the light- and heat-induced degradation, instead of module fabrication. These results highlight the need to control the distribution of Na in fielded CdTe modules to sustain long-term high-power output.},
doi = {10.1109/JPHOTOV.2019.2893854},
journal = {IEEE Journal of Photovoltaics},
number = 3,
volume = 9,
place = {United States},
year = {2019},
month = {2}
}

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This content will become publicly available on February 11, 2020
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