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.

Synthesis and Transistor Application of Bis[1]benzothieno[6,7- d:6',7'- d']benzo[1,2- b:4,5- b']dithiophenes.

Four bis[1]benzothieno[6,7- d:6',7'- d']benzo[1,2- b:4,5- b']dithiophene (BBTBDT) derivatives bearing substituents on the molecular long axis were synthesized, and their transistor performance was evaluated. Among the obtained compounds, OFET devices based on the 2,9-diphenyl-substituted derivative (1d) on a ß-PTS-modified Si/SiO2 substrate yielded the best morphological and crystalline structures, resulting in the highest hole mobility, as high as 0.16 cm2 V-1 s-1, and a low threshold voltage of -8 V. In the solid state, 1d formed a highly ordered and crystalline edge-on structure, which facilitated effective carrier transport. The detailed structure-property relationships were also disclosed by GIWAXS analysis, atomic force microscopy measurements, and theoretical calculations.