Enhanced Lifetime of Organic Photovoltaics based on P3HT: PCBM

The short lifetime of organic photovoltaics (OPVs) is a key factor that limits the commercialization of this flexible, low-cost PV technology. The sensitivity of OPVs to water and oxygen in the ambient environment has been found to be the major reason for their degradation. Therefore, techniques to protect the devices from water and oxygen are needed. This thesis introduces new methods designed to reduce the impact of water and oxygen on the lifetime of OPV devices. Two different methods were developed, both using insulating polymers. The first was the addition of an insulating polymer, such as poly (methyl methacrylate) (PMMA), or poly (ethylene glycol) (PEG), to a poly (3-hexylthiophene): [6, 6]-phenyl-C61-butyric acid methyl ester (P3HT: PCBM) OPV blend (ternary approach). It was found that this technique increased the lifetime of the OPVs, due to the ability of the insulating polymers to work as gettering agents for water. The second method that was used is laminating OPVs with an insulating polymer. It was found that this lamination technique enhanced the device lifetime more than the ternary approach due to the creation of a barrier to the ingress of both oxygen and water.