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Title: Novel Contact Materials for Improved Performance CdTe Solar Cells Final Report

Abstract

This program has explored a number of novel materials for contacts to CdTe solar cells in order to reduce the back contact Schottky barrier to zero and produce an ohmic contact. The project tested a wide range of potential contact materials including TiN, ZrN, CuInSe 2:N, a-Si:H and alloys with C, and FeS2. Improved contacts were achieved with FeS 2. As part of understanding the operation of the devices and controlling the deposition processes, a number of other important results were obtained. In the process of this project and following its conclusion it led to research that resulted in seven journal articles, nine conference publications, 13 talks presented at conferences, and training of eight graduate students. The seven journal articles were published in 2015, 2016, and 2017 and have been cited, as of March 2018, 52 times (one cited 19 times and two cited 11 times). We demonstrated high levels of doping of CIS with N but electrical activity of the resulting N was not high and the results were difficult to reproduce. Furthermore, even with high doping the contacts were not good. Annealing did not improve the contacts. A-Si:H was found to produce acceptable but unstable contacts, degrading evenmore » over a day or two, apparently due to H incorporation into the CdTe. Alloying with C did not improve the contacts or stability. The transition metal nitrides produced Schottky type contacts for all materials tested. While these contacts were found to be unsatisfactory, we investigated FeS 2 and found this material to be effective and comparable to the best contacts currently available. The contacts were found to be chemically stable under heat treatment and preferable to Cu doped contacts. Thus, we demonstrated an improved contact material in the course of this project. In addition, we developed new ways of controlling the deposition of CdTe and other materials, demonstrated the nature of defects in CdTe, and studied the distribution of conductivity and carrier type in CdTe devices. We demonstrated the conduction mechanism by which CdTe polycrystals improve the performance of the devices relative to single crystal devices. The mechanism shows that grain boundaries are conduction pathways for photogenerated electrons and that the corresponding holes are confined to the grains and therefore do not contribute to recombination.« less

Authors:
ORCiD logo [1];  [2];  [3]
  1. Colorado School of Mines, Golden, CO (United States)
  2. Old Dominion Univ., Norfolk, VA (United States)
  3. Univ. of Toledo, Toledo, OH (United States)
Publication Date:
Research Org.:
Colorado School of Mines, Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S)
OSTI Identifier:
1433077
Report Number(s):
DE-EE0005405
DOE Contract Number:
EE0005405
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 36 MATERIALS SCIENCE; Copper indium diselenide; silver indium diselenide

Citation Formats

Rockett, Angus, Marsillac, Sylvain, and Collins, Robert. Novel Contact Materials for Improved Performance CdTe Solar Cells Final Report. United States: N. p., 2018. Web. doi:10.2172/1433077.
Rockett, Angus, Marsillac, Sylvain, & Collins, Robert. Novel Contact Materials for Improved Performance CdTe Solar Cells Final Report. United States. doi:10.2172/1433077.
Rockett, Angus, Marsillac, Sylvain, and Collins, Robert. Sun . "Novel Contact Materials for Improved Performance CdTe Solar Cells Final Report". United States. doi:10.2172/1433077. https://www.osti.gov/servlets/purl/1433077.
@article{osti_1433077,
title = {Novel Contact Materials for Improved Performance CdTe Solar Cells Final Report},
author = {Rockett, Angus and Marsillac, Sylvain and Collins, Robert},
abstractNote = {This program has explored a number of novel materials for contacts to CdTe solar cells in order to reduce the back contact Schottky barrier to zero and produce an ohmic contact. The project tested a wide range of potential contact materials including TiN, ZrN, CuInSe2:N, a-Si:H and alloys with C, and FeS2. Improved contacts were achieved with FeS2. As part of understanding the operation of the devices and controlling the deposition processes, a number of other important results were obtained. In the process of this project and following its conclusion it led to research that resulted in seven journal articles, nine conference publications, 13 talks presented at conferences, and training of eight graduate students. The seven journal articles were published in 2015, 2016, and 2017 and have been cited, as of March 2018, 52 times (one cited 19 times and two cited 11 times). We demonstrated high levels of doping of CIS with N but electrical activity of the resulting N was not high and the results were difficult to reproduce. Furthermore, even with high doping the contacts were not good. Annealing did not improve the contacts. A-Si:H was found to produce acceptable but unstable contacts, degrading even over a day or two, apparently due to H incorporation into the CdTe. Alloying with C did not improve the contacts or stability. The transition metal nitrides produced Schottky type contacts for all materials tested. While these contacts were found to be unsatisfactory, we investigated FeS2 and found this material to be effective and comparable to the best contacts currently available. The contacts were found to be chemically stable under heat treatment and preferable to Cu doped contacts. Thus, we demonstrated an improved contact material in the course of this project. In addition, we developed new ways of controlling the deposition of CdTe and other materials, demonstrated the nature of defects in CdTe, and studied the distribution of conductivity and carrier type in CdTe devices. We demonstrated the conduction mechanism by which CdTe polycrystals improve the performance of the devices relative to single crystal devices. The mechanism shows that grain boundaries are conduction pathways for photogenerated electrons and that the corresponding holes are confined to the grains and therefore do not contribute to recombination.},
doi = {10.2172/1433077},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun Apr 15 00:00:00 EDT 2018},
month = {Sun Apr 15 00:00:00 EDT 2018}
}

Technical Report:

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