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 (