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Journal article

Charge carrier mobility and ageing of ZnPc/C60 solar cells

Abstract:
Cu and Zn Phtalocyanines (CuPc and ZnPc), and C60 are materials frequently used for organic Solar cell engineering. Their energy levels form a donor-acceptor junction, and they have high absorption coefficients and a complementary absorption for the Sun spectrum. We have investigated ageing properties of ZnPc/C60 Solar cells as they are influenced by the charge carrier mobility and variation of the potential barrier height of the ZnPc/C60 interface. The structures ITO/ZnPc/C60/C60:AOB/Al with a reasonable energy conversion efficiency of ∼1.5% were investigated. The samples were aged for 1300 hours upon illumination with blue LED, with peak emission at 475nm, and incident light power density of 10mW/cm2. The aged devices showed a strong and fast degradation of the short circuit current and of the fill factor after several hours followed by an almost constant behaviour of these values. The reference samples kept in the dark at the room temperature did show only very small changes in their I-V curves. Carrier mobility dependencies on electric field strength at different temperatures were measured by the Charge Extraction by Linearly Increasing Voltage (CELIV) method. It was demonstrated that mobility values decrease during degradation as compared to the reference samples. Nevertheless only mobility changes cannot explain the observed drop of device current. The increase of the effective barrier height at the interface of ZnPc and C60 by about 0.1eV from ∼0.55eV up to ∼0.65eV was observed in the aged samples. Meanwhile thermal activation energy values of the electrical conductivity grew from about 0.28eV prior to degradation up to about 0.34eV after ageing. © Taylor and Francis Group, LLC.
Publication status:
Published
Peer review status:
Peer reviewed

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Publisher copy:
10.1080/15421401003724175

Authors


More by this author
Institution:
University of Oxford
Division:
MPLS
Department:
Physics
Sub department:
Condensed Matter Physics
Role:
Author


Publisher:
Taylor and Francis
Journal:
Molecular Crystals and Liquid Crystals More from this journal
Volume:
522
Issue:
1
Pages:
61-74
Publication date:
2010-01-01
DOI:
EISSN:
1563-5287
ISSN:
1542-1406


Language:
English
Keywords:
Pubs id:
pubs:405405
UUID:
uuid:affec868-252a-4469-bfc1-8df177884039
Local pid:
pubs:405405
Source identifiers:
405405
Deposit date:
2013-09-26

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