Photochemical Transformations in Fullerene and Molybdenum Oxide Affect the Stability of Bilayer Organic Solar Cells

Thin films of fullerene C-60 and molybdenum oxide (MoO3) are ubiquitously used as the electron acceptor material and hole extraction interfacial layer for the fabrication of organic photovoltaic (OPV) cells. It is well known that light exposure induces color changes in MoO3 (photochromism) and the formation of intermolecular bonds between C-60 molecules (photopolymerization). The influence of these photoinduced reactions on the long-term stability of OPV cells, however, has not previously been studied in detail. Here, a study and discussion of the early (<5 days) aging mechanisms occurring in illuminated ITO/MoO3/organic cyanine dye/C-60/Alq(3)/Ag bilayer solar cells under nitrogen atmosphere is presented. A degradation process at the organic heterojunction is identified and the formation of Mo5+ species during illumination is found to adversely affect cell behavior. For these widely used materials, the results suggest that light processing is a first necessary step before OPV characteristics can be meaningfully rated.


Published in:
Advanced Energy Materials, 5, 2
Year:
2015
Publisher:
Weinheim, Wiley-V C H Verlag Gmbh
ISSN:
1614-6832
Keywords:
Note:
Empa + EPFL
Laboratories:




 Record created 2015-05-29, last modified 2018-01-28


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