A computational study of anisotropic charge transport in air-stable fluorinated benzobisbenzothiophene (FBBBT) derivatives

A computational study of anisotropical charge transport properties of fluorinated benzobisbenzothiohphene derivatives ( FBBBT ) is presented. The values of I P adia of all FBBBTs are found in the range of 6.00–6.20 eV inferring the fact that the investigated compounds have ambient air-stability. In addition, the energy levels of FBBBT s are found to be lower than those of benzobisbenzothiophene ( BBBT ) compound indicating higher charge carrier stability in the former. Hirshfield surface analyses showed that, in all the studied compounds, the principal identifiable interaction were mostly due to F⋯H and H⋯H intermolecular couplings with no contribution from S⋯S bondings. The calculated maximum μ hole ( μ elec ) value of the compounds FBBBT-a and FBBBT-b was found to be 0.483 (0.794) cm 2 V − 1 s − 1 and 0.688 (0.542) cm 2 V − 1 s − 1 respectively in the direction of transistor channel (Φ = 93.39 ∘ (273.30 ∘ ) for FBBBT-a and Φ = 92.24 ∘ /272.72 ∘ for FBBBT-b ). For FBBBT-c , the maximum μ elec ( μ hole ) value of 0.933 (0.233) cm 2 V − 1 s − 1 appeared for Φ = 0 ∘ /179.90 ∘ . In addition, the compounds FBBBT-a and FBBBT-b possess two additional fluorine atoms attached at the X positions in the backbone, which result in an increment in μ elec values (1.4 times and 0.78 times higher than μ hole ) in these two compounds at a particular crystal direction.