Delineation of the effects of water and oxygen on the degradation of organic photovoltaic devices

Performance degradation is one of the most important metrics for the evaluation of solar cells. In this paper we show that water is the primary species determining the degradation rate of electrical properties of Al/Ca/P3HT:PC61BM/PEDOT:PSS/ITO photovoltaic cells. This is accomplished by varying the diffusion rate of reactive species (oxygen, water) present in air through solar cell encapsulation with polyethylene terephthalate (PET), Kapton and silica glass.

► P3HT:PC61BM-based solar cells were encapsulated using PET, Kapton and silica glass.
► Encapsulation controls the access of water and oxygen to solar cell surface, thus, determining performance degradation rate.
► Kinetics of performance degradation suggests that water determines degradation rate of Al/Ca/P3HT:PC61BM/PEDOT:PSS/ITO solar cells.
► GIWAXS measurements show no change in film crystallinity, while significant degradation of device performance is observed.