Synthesis and Physicochemical Properties of Dibenzo­[2,3‑d:2′,3′‑d′]­anthra­[1,2‑b:5,6‑b′]­dithiophene (DBADT) and Its Derivatives: Effect of Substituents on Their Molecular Orientation and Transistor Properties

We have synthesized dibenzo­[2,3-d:2′,3′-d′]­anthra­[1,2-b:5,6-b′]­dithiophene (DBADT) and several derivatives bearing alkyl and phenyl groups at various positions. The optical and electrochemical properties of the synthesized compounds were investigated. All the fabricated OFET devices exhibited typical p-type behavior under ambient conditions, and diphenyl-substituted analogue-based OFET devices showed excellent mobility, as high as 0.66 cm² V^–1 s^–1. The surface morphology and molecular orientation in thin films were also investigated using atomic force microscopy (AFM) and two-dimensional grazing incidence X-ray diffraction (2D-GIXD). It was found that the substituents and their positions affect the molecular orbitals, molecular orientation, and morphology of the thin films, producing different FET performance.