Anisotropic electron mobility in fluorene-PPV and fluorene-MEH-PPV

Polyfluorene copolymers are attractive semiconductor materials, in particular for applications in the organic electronics field. They are versatile to be chemically modified and allow a tuning of the emission to cover the entire visible spectrum. A better understanding of the fundamental aspects of the nature of electronic structure and charge transport properties contribute to the improvement of optoelectronic properties of polymeric materials. Here, we provide a structure–property relationship for models of fluorene-PPV and fluorene-MEH-PPV copolymers, using molecular quantum mechanics modelling. The anisotropy is discussed revisiting Mulliken's transition moment theory. Accordingly, our results show that electron mobility occurs preferentially intrachain for both copolymers. Moreover, the interchain electron mobility has the most propensity to occur via π-stacking interactions.