Sexithiophene films on ordered and disordered TiO2(110) surfaces: Electronic, structural and morphological properties

What is it about?

Nowadays, many - especially - optoelectronic devices employ organic semiconducting films, which are based on conjugated molecules and polymers. Properties of such films are highly anisotropic due to the limited symmetry of molecules themselves. Given various applications of molecular films, distinct molecular orientation is necessary. Accordingly, the control of molecular orientation is a principal issue of the molecular growth. The study questioned the current view relating the lying molecular orientation with the high interaction strength between the adsorbed molecule and the substrate. Instead, it was demonstrated that the lying molecular orientation is induced by an oriented diffusion of adsorbed molecules over the substrate surface, while the upright orientation is a consequence of absence of the oriented diffusion.

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Why is it important?

The study proposes a novel growth model of evaporated small molecules describing a principal factor affecting the molecular orientation in the grown film.