Short-term metal/organic interface stability investigations of organic photovoltaic devices

As organic photovoltaic (OPV) devices have begun to move toward initial applications, issues of their stability are becoming increasingly important. The de facto standard OPV devices are made from a blend of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM), and these serve as a test bed for lifetime testing. Delamination, oxidation, and chemical interactions at the metal electrode/organic interface have been posited as degradation pathways in organic electronic devices.[1,2] Here, two short-term experiments were employed to evaluate the stability of this interface in the light and dark. Full devices and unprotected organic surfaces were separately examined, and both were found to be stable in air over the course of 10's of minutes while in the dark. While unprotected devices were stable (less than 20% loss in efficiency) in air for 100 minutes under constant 1-sun illumination, unprotected organic surfaces were not, and good devices could not be made on them subsequently.