In organic solar cells the efficiency can be increased by using an additive. However in organic photovoltaics what the use of additives does to the underlying structure is not well understood. The additive 1,8-diodooctane (DIO) is highly used in organic photovoltaics. One major requirement for an additive to be a good additive is having preferential solubility to one of the components (typically the fullerene). However, very little information still exists in the literature on the solubility of conjugated polymers in pure additives such as DIO. In this proposal we aim to study the solubility and aggregation behaviour of these conjugated polymers in DIO and in DIO:CB-d5 solutions using SANS. This knowledge will be crucial for the comprehension of the effect of additives in organic photovoltaics and can be leveraged to the development of more efficient OPV devices.