Degradation Mechanisms in Organic Photovoltaic Devices

Photovoltaic devices are subjected to many stresses during their lifetimes: thermal stress, continuous illumination, and mechanical deformation. Depending on the quality of the encapsulation barrier used, contaminants such as water and oxygen can also diffuse into the devices. These different factors can lead to intrinsic degradation (e.g. morphological changes) as well as extrinsic degradation (e.g. photo-oxidation). Numerous degradation pathways can be exhibited by a device under operating conditions, and in order to understand the different mechanisms present, it is important to study ageing systematically. This includes studying single components of devices, such as the donor organic semi-conductor, or complete devices - including, in particular the organic-organic or organic-inorganic interfaces.