Understanding light-induced changes to the miscibility of polymer/fullerene systems

Polymer/fullerene blends represent the most common form of organic solar cell. This proposal forms part of a wider effort in which our motivation is to complement solar cell optimisation strategies, with in-depth studies aimed at increasing the fundamental understanding of the materials science within polymer/fullerene thin films. This proposal focuses on device stability issues by looking at the interplay between (both temporary and permanent) light-induced chemical changes and miscibility in polymer/fullerene thin-films. We will investigate this by performing controlled (visible light) illumination experiments, followed by thermal annealing on model fullerene/polymer (polystyrene - PS) systems. Illumination and heating will be followed by specular reflectivity measurements to characterise composition profiles as a function of illumination conditions and PS MW.