Conjugated organic semiconductors form an exciting class of materials that can be used in a variety of cutting edge technologies including organic light-emitting diodes (OLED), solar cells and chemical sensors. In all these applications the thin film morphology and interfacial interactions are key characteristics. The most efficient OLEDs are generally composed of several organic layers deposited sequentially, with each performing a specific role. In a previous study we have used neutron reflectometry to study layered OLED structures and found that, on mild thermal annealing, the materials diffuse into one another in a short period of time, which has significant implications for their long term stability and performance. In this experiment we propose to study the interdiffusion of OLED materials in real time.