A theoretical investigation of the effect of fluorination and bromination on the optoelectronic properties of tetrathienophenazine derivatives

International audience; The electronic and optical properties of crystalline tetrathienophenazine derivatives (l-TTP, m-TTP, t-TTP) and their four fluorinated and brominated derivatives are predicted using density functional theory within the generalized gradient approximation and including the van der Waals weak interactions. We analyze how the position of sulfur atoms and fluorination and bromination modify the charge transport in TTP derivatives. Our results show that the introduction of bromine substituents into TTP derivatives has a stronger effect than fluorination. The introduction of the fluorine atoms improves the hole transport in the l-TTP derivatives, while bromine atoms improve both hole and electron transport of the three TTP derivatives. Our findings suggest a new series of promising ambipolar organic materials.