Phase mixing behaviour in evaporated thin films

The photovoltaic active layer of organic photovoltaics (OPVs) consists of a mixture of at least two kinds of energetically off-set organic molecules, which gives rise to a complex microstructure across multiple length scales from Angstroms to the micrometre scale. A common method to study the mixing of Polymer:Fullerene systems has been Small Angle Neutron Scattering (SANS), but it has so far remained unused for vacuum evaporated systems, which are closest to commercial viability. We have recently, successfully, demonstrated the use of SANS to study the mixing behaviour of OPV evaporated thin films as a function of composition and deposition conditions. We seek to expand upon our preliminary results to study the phase behaviour of vacuum evaporated thin films in terms of the domains sizes, shapes and purity to improve device performance.