Overcoming interface losses in organic solar cells by applying low temperature, solution processed aluminum-doped zinc oxide electron extraction layers

Intrinsic zinc oxide (ZnO) is widely used as an electron extraction layer (EEL) for inverted polymer solar cells. Despite the excellent device performance, a major drawback for large area production is its low conductivity. Using microscopic simulations, we derived a technically reasonable threshold...

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Bibliographic Details
Published in:Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2013-01, Vol.1 (19), p.6004-6009
Main Authors: Stubhan, Tobias, Litzov, Ivan, Li, Ning, Salinas, Michael, Steidl, Matthias, Sauer, Gerhard, Forberich, Karen, Matt, Gebhard J., Halik, Marcus, Brabec, Christoph J.
Format: Article
Language:English
Subjects:
Aluminum
Azo
Devices
Extraction
Photovoltaic cells
Resistivity
Solar cells
Zinc oxide
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Summary:Intrinsic zinc oxide (ZnO) is widely used as an electron extraction layer (EEL) for inverted polymer solar cells. Despite the excellent device performance, a major drawback for large area production is its low conductivity. Using microscopic simulations, we derived a technically reasonable threshold value of 10 super(-3) S cm super(-1) for the conductivity required to overcome transport limitations. For conductivity values typical for ZnO we observed the interface layer thickness restriction at only a few tens of nanometers, either as a fill factor drop due to serial resistance, eventually accompanied by a second diode behavior, or by the need for light soaking. Higher conductive aluminum-doped zinc oxide (AZO), which was introduced earlier, meets the desired conductivity threshold, however, at the cost of high temperature processing. High annealing temperatures (>150 degree C) significantly improve the electrical properties of ZnO, but prohibit processing on plastic substrates or organic active layers. Here we report on AZO layers from a sol-gel precursor, which has been already reported to give sufficiently high conductivities at lower processing temperatures (
ISSN:2050-7488
2050-7496
DOI:10.1039/c3ta10987a