About Establis

Earth receives enough sunlight in one hour to satisfy all human needs in a year. Using solar energy will reduce harmful CO2 emissions and resolve the forthcoming energy deficit. The market for stable, mass-produced Organic Solar Cells is estimated at one billion Euros by 2016.

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ESTABLIS will train a team of 11 PhDs and 4 Postdocs to become the scientific leaders in industry and academia. ESTABLIS Fellows will excel.

Research on organic solar cells

Complementarity is at the heart of Establis. To develop Organic Solar Cells requires a concerted combination of physical, synthetic and modelling capabilities. Establis members are working together–across preconceived scientific boundaries–to accelerate the production of Organic Solar Cells.

Partnerships & collaborations

Our Industrial Partners and Associate Partners ensure that the training and technology is economically feasible.

EU support

The EEC is constructively investing more than 3.9 M€ in Establis to train, research and collaborate at the highest international level and ensure our energy platform for the 21st century.

Scientific results

Poster Presentation at ISOS7 (Barcelone, 2014) - Delamination in OPV Devices: A New Technique to Identify the Weakest Mechanical Point

A. Gregoria*, S. Schumannb, A. Tournebizec, A. Elschnerb, H. Peisertc, T. Chasséc, C. Dagron-Lartigaua, R. C. HiornsdA. Allala

a. EPCP, IPREM (UMR-5254), Université de Pau et des Pays de l’Adour, 2 avenue du Président Angot, 64053 Pau, Cedex 09, France
b. Heraeus Precious Metals GmbH & Co. KG, Electronic Materials Division, Chempark Leverkusen/Gebäude B 202, D-51368 Leverkusen, Germany
c. Eberhard Karls Universität Tübingen, Institut für Physikalische und Theoretische Chemie, Auf der Morgenstelle, 18 72076 Tübingen, Germany
d. CNRS, EPCP, IPREM (UMR-5254), 2 avenue du Président Angot, 64053 Pau,Cedex 09, France
 
Organic photovoltaic (OPV) devices are one of the most promising applications of organic semiconductors due to their compatibility with flexible plastic substrates resulting in light weight, inexpensive and decorative products. While the electrical failure mechanisms in organic photovoltaic devices have been thoroughly investigated, little is known about their mechanical stability, which is as important and critical to ensure long term reliability [1]. The characteristic thin films stresses of each layer present in organic solar cells, in combination with other possible fabrication, handling and operational stresses, provide the mechanical driving force for delamination of weak interfaces or even their decohesion, leading to a loss of device integrity and performance[2].
In this study, we developed a technique to probe weak layers or interfaces in inverted polymer:fullerene solar cells, establishing a new set-up for the so-called probe tack [3] making it similar to a pull-off test4, with an improved control on the test parameters. The technique has been developed using an inverted device, with the structure glass/ITO/ZnO/P3HTRazzCBM/PEDOTRazzSS/Ag. The delaminated devices showed that the
weakest point is localized at the active layer/hole transporting layer interface, in good agreement with the literature [1,2].
The technique has been extended varying both sensitive layers, using different p-type low bandgap (co)polymers for the active layer (Si-PCPDTBT and PDTSTzTz) in combination with two different PEDOTRazzSS formulations, the water based CleviosTM HTL Solar and a new organic solvents based CleviosTM HTL Solar 2.
After mechanical tests, the upper and lower surfaces have been characterized by contact angle measurement, AFM and XPS to locate the fracture point. A difference in the stress at break for devices made with different combinations of active and hole transporting layers is visible, suggesting different fracture paths, as confirmed by surface characterization and could be correlated to the different behavior of the active layer with the two PEDOTRazzSS formulations.
 
Acknowledgments
The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2011 under grant agreement ESTABLIS n° 290022).
 
References
1 Jorgensen, M.; Norrman, K.; Gevorgyan, S. A.; Tromholt,T.; Andreasen, B.; Krebs F. C. Adv. Mater. 24, 5, 2012
2 Dupont, S. R.; Oliver, M.; Krebs, F. C.; Dauskardt, R. H. Solar Energy Materials & Solar Cells 97, 2012, 171–175
3 C. Creton and P. Fabre Adh. Science and Engeneering I, Elsevier 2002
4 ASTM D4541-09