  The anisotropic charge carrier mobilities of two phenancene series compounds
such as dibenzo[a,c]picene (DBP) and tribenzo[a,c,k]tetraphene (TBT) is
investigated based on the first-principle calculations and Marcus-Hush theory.
The molecular packing patterns in organic crystal play an important role for
determing the charge carrier mobility and hence the device efficiencies
designed from the organic materials. Among the studied molecules, TBT shows a
maximum anisotropic hole ($\mu_h=0.129\ cm^2V^{-1}s^{-1}$) and electron
($\mu_h=1.834\ cm^2V^{-1}s^{-1}$) mobility, hence possesses an ambipolar
semiconducting character. The frontier molecular orbital analyses proved the
better air-stability of the studied compounds than the conventional pentacene,
because of their higher HOMO energy levels. Band structure calculations of the
studied compounds have also been investigated. From non-linear optical (NLO)
properties anysis, we found the TBT compound shows more NLO response than DBP.
