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Title: Measurement of Band Offsets and Shunt Resistance in CdTe Solar Cells Through Temperature and Intensity Dependence of Open Circuit Voltage and Photoluminescence

Abstract

Band offsets at the back contact and front window layer in CdTe-based solar cells affect photovoltaic performance and challenge standard characterization methods. By analyzing the temperature and excitation dependence of both open circuit voltage and absolute photoluminescence intensity, we show that the effects band offsets can be separated from the effects of recombination and shunting. Solar cells were grown with MgZnO window layers and compared to cells with CdS window layers containing varying amounts of oxygen. It was demonstrated that band alignment rather than reduced recombination velocity is the reason for the success of MgZnO as a front interface contact. An assortment of thin back contact interlayers were also deposited, and a PbTe interlayer showed some promise as an Ohmic contact to the CdTe, though it appears to induce a photoconductive shunt. Finally, we show that the shunting resistance given by a standard current-voltage curve technique generally does not represent a physically meaningful quantity unless it is well below one kiloOhm square cm.

Authors:
 [1];  [1];  [1]; ORCiD logo [2];  [2]; ORCiD logo [2];  [2];  [3];  [3];  [3];  [1];  [2];  [1];  [1];  [3];  [1]
  1. Texas State University
  2. National Renewable Energy Laboratory (NREL), Golden, CO (United States)
  3. University of Toledo
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:
1569453
Report Number(s):
NREL/JA-5K00-75058
DOE Contract Number:  
AC36-08GO28308
Resource Type:
Journal Article
Journal Name:
Solar Energy
Additional Journal Information:
Journal Volume: 189
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 36 MATERIALS SCIENCE; photovoltaic device characterization; loss analysis; model fitting; contact barrier; recombination; injection dependence

Citation Formats

Swartz, Craig H., Rab, Sadia R., Paul, Sanjoy, Van Hest, Marinus F, Dou, Benjia, Luther, Joseph M, Pach, Gregory, Grice, Corey R., Li, Dengbing, Bista, Sandip S., LeBlanc, Elizabeth G., Reese, Matthew O, Holtz, Mark W., Myers, Thomas H., Yan, Yanfa, and Li, Jian V. Measurement of Band Offsets and Shunt Resistance in CdTe Solar Cells Through Temperature and Intensity Dependence of Open Circuit Voltage and Photoluminescence. United States: N. p., 2019. Web. doi:10.1016/j.solener.2019.07.057.
Swartz, Craig H., Rab, Sadia R., Paul, Sanjoy, Van Hest, Marinus F, Dou, Benjia, Luther, Joseph M, Pach, Gregory, Grice, Corey R., Li, Dengbing, Bista, Sandip S., LeBlanc, Elizabeth G., Reese, Matthew O, Holtz, Mark W., Myers, Thomas H., Yan, Yanfa, & Li, Jian V. Measurement of Band Offsets and Shunt Resistance in CdTe Solar Cells Through Temperature and Intensity Dependence of Open Circuit Voltage and Photoluminescence. United States. doi:10.1016/j.solener.2019.07.057.
Swartz, Craig H., Rab, Sadia R., Paul, Sanjoy, Van Hest, Marinus F, Dou, Benjia, Luther, Joseph M, Pach, Gregory, Grice, Corey R., Li, Dengbing, Bista, Sandip S., LeBlanc, Elizabeth G., Reese, Matthew O, Holtz, Mark W., Myers, Thomas H., Yan, Yanfa, and Li, Jian V. Fri . "Measurement of Band Offsets and Shunt Resistance in CdTe Solar Cells Through Temperature and Intensity Dependence of Open Circuit Voltage and Photoluminescence". United States. doi:10.1016/j.solener.2019.07.057.
@article{osti_1569453,
title = {Measurement of Band Offsets and Shunt Resistance in CdTe Solar Cells Through Temperature and Intensity Dependence of Open Circuit Voltage and Photoluminescence},
author = {Swartz, Craig H. and Rab, Sadia R. and Paul, Sanjoy and Van Hest, Marinus F and Dou, Benjia and Luther, Joseph M and Pach, Gregory and Grice, Corey R. and Li, Dengbing and Bista, Sandip S. and LeBlanc, Elizabeth G. and Reese, Matthew O and Holtz, Mark W. and Myers, Thomas H. and Yan, Yanfa and Li, Jian V.},
abstractNote = {Band offsets at the back contact and front window layer in CdTe-based solar cells affect photovoltaic performance and challenge standard characterization methods. By analyzing the temperature and excitation dependence of both open circuit voltage and absolute photoluminescence intensity, we show that the effects band offsets can be separated from the effects of recombination and shunting. Solar cells were grown with MgZnO window layers and compared to cells with CdS window layers containing varying amounts of oxygen. It was demonstrated that band alignment rather than reduced recombination velocity is the reason for the success of MgZnO as a front interface contact. An assortment of thin back contact interlayers were also deposited, and a PbTe interlayer showed some promise as an Ohmic contact to the CdTe, though it appears to induce a photoconductive shunt. Finally, we show that the shunting resistance given by a standard current-voltage curve technique generally does not represent a physically meaningful quantity unless it is well below one kiloOhm square cm.},
doi = {10.1016/j.solener.2019.07.057},
journal = {Solar Energy},
number = ,
volume = 189,
place = {United States},
year = {2019},
month = {8}
}