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Title: The roles of ZnTe buffer layers on CdTe solar cell performance

Abstract

The use of ZnTe buffer layers at the back contact of CdTe solar cells has been credited with contributing to recent improvements in both champion cell efficiency and module stability. To better understand the controlling physical and chemical phenomena, high resolution transmission electron microscopy (HR-TEM) and atom probe tomography (APT) were used to study the evolution of the back contact region during rapid thermal processing (RTP) of this layer. After activation the ZnTe layer, initially nanocrystalline and homogenous, transforms into a bilayer structure consisting of a disordered region in contact with CdTe characterized by significant Cd–Zn interdiffusion, and a nanocrystalline layer that shows evidence of grain growth and twin formation. Copper, co-evaporated uniformly within ZnTe, is found to dramatically segregate and aggregate after RTP, either collecting near the ZnTe|Au interface or forming CuxTe clusters in the CdTe layer at defects or grain boundaries near the interface. Analysis of TEM images revealed that Zn accumulates at the edge of these clusters, and three-dimensional APT images confirmed that these are core–shell nanostructures consisting of Cu1.4Te clusters encased in Zn. These changes in morphology and composition are related to cell performance and stability.

Authors:
 [1];  [2];  [1];  [1];  [3];  [1];  [1];  [4];  [2]
  1. Colorado School of Mines, Golden, CO (United States)
  2. Loughborough Univ., Leicestershire (United Kingdom)
  3. Colorado School of Mines, Golden, CO (United States); National Renewable Energy Lab. (NREL), Golden, CO (United States)
  4. National Renewable Energy Lab. (NREL), Golden, CO (United States)
Publication Date:
Research Org.:
Stanford Univ., CA (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Renewable Power Office. Solar Energy Technologies Office
OSTI Identifier:
1579808
Alternate Identifier(s):
OSTI ID: 1359875
Grant/Contract Number:  
EE0004946; AC36-08GO28308
Resource Type:
Accepted Manuscript
Journal Name:
Solar Energy Materials and Solar Cells
Additional Journal Information:
Journal Volume: 147; Journal Issue: C; Journal ID: ISSN 0927-0248
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY

Citation Formats

Wolden, Colin A., Abbas, Ali, Li, Jiaojiao, Diercks, David R., Meysing, Daniel M., Ohno, Timothy R., Beach, Joseph D., Barnes, Teresa M., and Walls, John M. The roles of ZnTe buffer layers on CdTe solar cell performance. United States: N. p., 2015. Web. doi:10.1016/j.solmat.2015.12.019.
Wolden, Colin A., Abbas, Ali, Li, Jiaojiao, Diercks, David R., Meysing, Daniel M., Ohno, Timothy R., Beach, Joseph D., Barnes, Teresa M., & Walls, John M. The roles of ZnTe buffer layers on CdTe solar cell performance. United States. doi:10.1016/j.solmat.2015.12.019.
Wolden, Colin A., Abbas, Ali, Li, Jiaojiao, Diercks, David R., Meysing, Daniel M., Ohno, Timothy R., Beach, Joseph D., Barnes, Teresa M., and Walls, John M. Wed . "The roles of ZnTe buffer layers on CdTe solar cell performance". United States. doi:10.1016/j.solmat.2015.12.019. https://www.osti.gov/servlets/purl/1579808.
@article{osti_1579808,
title = {The roles of ZnTe buffer layers on CdTe solar cell performance},
author = {Wolden, Colin A. and Abbas, Ali and Li, Jiaojiao and Diercks, David R. and Meysing, Daniel M. and Ohno, Timothy R. and Beach, Joseph D. and Barnes, Teresa M. and Walls, John M.},
abstractNote = {The use of ZnTe buffer layers at the back contact of CdTe solar cells has been credited with contributing to recent improvements in both champion cell efficiency and module stability. To better understand the controlling physical and chemical phenomena, high resolution transmission electron microscopy (HR-TEM) and atom probe tomography (APT) were used to study the evolution of the back contact region during rapid thermal processing (RTP) of this layer. After activation the ZnTe layer, initially nanocrystalline and homogenous, transforms into a bilayer structure consisting of a disordered region in contact with CdTe characterized by significant Cd–Zn interdiffusion, and a nanocrystalline layer that shows evidence of grain growth and twin formation. Copper, co-evaporated uniformly within ZnTe, is found to dramatically segregate and aggregate after RTP, either collecting near the ZnTe|Au interface or forming CuxTe clusters in the CdTe layer at defects or grain boundaries near the interface. Analysis of TEM images revealed that Zn accumulates at the edge of these clusters, and three-dimensional APT images confirmed that these are core–shell nanostructures consisting of Cu1.4Te clusters encased in Zn. These changes in morphology and composition are related to cell performance and stability.},
doi = {10.1016/j.solmat.2015.12.019},
journal = {Solar Energy Materials and Solar Cells},
number = C,
volume = 147,
place = {United States},
year = {2015},
month = {12}
}

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Cited by: 19 works
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