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Title: Investigating the Influence of Interfacial Contact Properties on Open Circuit Voltages in Organic Photovoltaic Performance: Work Function Versus Selectivity

Abstract

The role of work function and thermodynamic selectivity of hole collecting contacts on the origin of open circuit voltage (VOC) in bulk heterojunction organic photovoltaics is examined for poly(N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole) (PCDTBT) and [6,6]-phenyl-C71 butyric acid methyl ester (PC71BM) solar cells. In the absence of a charge selective, electron blocking contact, systematic variation of the work function of the contact directly dictates the VOC, as defined by the energetic separation between the relative Fermi levels for holes and electrons, with little change in the observed dark saturation current, J 0. Improving the charge selectivity of the contact through an increased barrier to electron injection from the fullerene in the blend into the hole contact results in a decreased reverse saturation current (decreased J 0 and increased shunt resistance, R SH) and improved V OC. Based on these observations, we provide a set of contact design criteria for tuning the V OC in bulk heterojunction organic photovoltaics.

Authors:
; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC) (United States). Center for Interface Science: Solar Electric Materials (CISSEM)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1382304
DOE Contract Number:  
SC0001084
Resource Type:
Journal Article
Journal Name:
Advanced Energy Materials
Additional Journal Information:
Journal Volume: 3; Journal Issue: 5; Related Information: CISSEM partners with the University of Arizona (lead); Georgia Institute of Technology; National Renewable Energy Laboratory; Princeton University; University of Washington; Journal ID: ISSN 1614-6832
Publisher:
Wiley
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; solar (photovoltaic), electrodes - solar, charge transport, synthesis (novel materials), synthesis (self-assembly), synthesis (scalable processing)

Citation Formats

Ratcliff, Erin L., Garcia, Andres, Paniagua, Sergio A., Cowan, Sarah R., Giordano, Anthony J., Ginley, David S., Marder, Seth R., Berry, Joseph J., and Olson, Dana C. Investigating the Influence of Interfacial Contact Properties on Open Circuit Voltages in Organic Photovoltaic Performance: Work Function Versus Selectivity. United States: N. p., 2013. Web. doi:10.1002/aenm.201200669.
Ratcliff, Erin L., Garcia, Andres, Paniagua, Sergio A., Cowan, Sarah R., Giordano, Anthony J., Ginley, David S., Marder, Seth R., Berry, Joseph J., & Olson, Dana C. Investigating the Influence of Interfacial Contact Properties on Open Circuit Voltages in Organic Photovoltaic Performance: Work Function Versus Selectivity. United States. doi:10.1002/aenm.201200669.
Ratcliff, Erin L., Garcia, Andres, Paniagua, Sergio A., Cowan, Sarah R., Giordano, Anthony J., Ginley, David S., Marder, Seth R., Berry, Joseph J., and Olson, Dana C. Wed . "Investigating the Influence of Interfacial Contact Properties on Open Circuit Voltages in Organic Photovoltaic Performance: Work Function Versus Selectivity". United States. doi:10.1002/aenm.201200669.
@article{osti_1382304,
title = {Investigating the Influence of Interfacial Contact Properties on Open Circuit Voltages in Organic Photovoltaic Performance: Work Function Versus Selectivity},
author = {Ratcliff, Erin L. and Garcia, Andres and Paniagua, Sergio A. and Cowan, Sarah R. and Giordano, Anthony J. and Ginley, David S. and Marder, Seth R. and Berry, Joseph J. and Olson, Dana C.},
abstractNote = {The role of work function and thermodynamic selectivity of hole collecting contacts on the origin of open circuit voltage (VOC) in bulk heterojunction organic photovoltaics is examined for poly(N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole) (PCDTBT) and [6,6]-phenyl-C71 butyric acid methyl ester (PC71BM) solar cells. In the absence of a charge selective, electron blocking contact, systematic variation of the work function of the contact directly dictates the VOC, as defined by the energetic separation between the relative Fermi levels for holes and electrons, with little change in the observed dark saturation current, J0. Improving the charge selectivity of the contact through an increased barrier to electron injection from the fullerene in the blend into the hole contact results in a decreased reverse saturation current (decreased J0 and increased shunt resistance, RSH) and improved VOC. Based on these observations, we provide a set of contact design criteria for tuning the VOC in bulk heterojunction organic photovoltaics.},
doi = {10.1002/aenm.201200669},
journal = {Advanced Energy Materials},
issn = {1614-6832},
number = 5,
volume = 3,
place = {United States},
year = {2013},
month = {2}
}

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