Effects of molecular organization on exciton diffusion in thin films of bioinspired light-harvesting molecules

Efficient exciton diffusion in light-harvesting organic materials is of great importance for the development of cheap and flexible photovoltaic devices. Bioinspired molecular materials such as derivatives of phthalocyanine and porphyrin offer promising prospects for the realization of efficient exciton diffusion. The chemical composition of these molecules is found to strongly affect the molecular organization in thin films and in turn the efficiency of exciton diffusion. High singlet exciton diffusion coefficients exceeding 10−6 m2 s−1 have been found. This value is similar to that for the natural chlorosomal bacterio-chlorophyll, which exhibits the highest exciton diffusion coefficient for self-assembled systems.