(581c) Role of Phase Morphology on the Electronic and Structural Landscape of Organic Semiconductors

In today’s organic electronic research, where the role of morphology has been identified as a key parameter in determining device performance, it is critical to devise tools to manipulate, in a controlled fashion, the structure formation of functional organic materials. Blending of polymers, by solution processing, is one useful strategy that enables such control. In my talk, I will highlight how the microstructure and phase morphology of specific polymer blends can be fine-tuned over various length scales, from local arrangement and packing, long-range order to larger-scale phase separation, characterized among other things by optical microscopy and X-ray scattering techniques. We also establish (non-equilibrium) temperature-composition phase diagrams to provide a future platform to predict and design phase morphology of polymer blends. We exemplify our approach using poly(vinylidene difluoride) (PVDF)-based blends with semiconducting polymers such as poly(3-hexylthiophene-2,5-diyl) (P3HT) and poly[(5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl)-alt-(3,3’’’-di(2-octyldodecyl)-2,2’,5’,2’’,5’’,2’’’-quaterthiophen-5,5’’’-diyl)] (PffBT4T-2OD). Addition of the rather polar PVDF may also assist manipulation of the dielectric constant of the blend, which generally is a limiting factor in exciton dissociation in devices such as organic photovoltaics (OPVs). Photo-physical processes of resulting blends are probed with ultra-fast spectroscopic methods to determine the effect of polymer blending and phase morphology on charge separation and transport. This should allow us to obtain detailed insights in the structural and optical landscape of these multicomponent systems.