Abstract
Inflection point behaviour is often observed in the current-voltage (IV) curve of polymer and organic solar cells. This phenomenon
is examined in the context of flexible roll-to-roll (R2R) processed polymer solar cells in a large series of devices with a layer
structure of: PET-ITO-ZnO-P3HT:PCBM-PEDOT:PSS-Ag. The devices were manufactured using a combination of slot-die
coating and screen printing; they were then encapsulated by lamination using a polymer based barrier material. All manufacturing
steps were carried out in ambient air. The freshly prepared devices showed a consistent inflection point in the IV curve and a
corresponding poor performance or lack of photovoltaic behaviour. Upon exposure to 1000 Wm-2 illumination at ca. 85 oC and
repeated IV scans (photo-annealing) the inflection point gradually disappeared, and performance drastically increased over time.
The characteristics and stability of this “photo-annealing” behaviour was further investigated by studying the effects of several key
factors: temperature, illumination, and atmosphere. The results consistently showed that the inflection point is a dynamic interface
phenomenon which can be removed under specific conditions. Subsequently, chemical characterization of device interfaces was
carried out in order to identify possible chemical processes that are related to photo-annealing. A possible mechanism based on
ZnO photoconductivity, photooxidation and redistribution of oxygen inside the cell is proposed, and it is anticipated that the
findings are applicable to various other device structures based on semiconducting oxides. The findings may have influences on the
possibilities and scale-up of polymer solar technologies.
Original language | English |
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Title of host publication | Book of abstracts |
Publisher | Danmarks Tekniske Universitet, Risø Nationallaboratoriet for Bæredygtig Energi |
Publication date | 2010 |
Publication status | Published - 2010 |
Event | 3rd International Summit on OPV Stability - Risø, Denmark Duration: 21 Oct 2010 → 29 Oct 2010 Conference number: 3 http://indico.conferences.dtu.dk/conferenceDisplay.py?ovw=True&confId=35 |
Conference
Conference | 3rd International Summit on OPV Stability |
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Number | 3 |
Country/Territory | Denmark |
City | Risø |
Period | 21/10/2010 → 29/10/2010 |
Internet address |
Keywords
- Polymer solar cells
- Solar energy