Electronic polarization in dipolar organic molecular semiconductors: The case study of 1,2,3,4-tetrafluoro-6,7-dimethylnaphthalene crystal

Abstract

Electronic polarization has an important impact on the site energies of charge carriers that play a key role in determining the charge transport in organic semiconductors. Dipolar molecules have strong intermolecular interactions and widespread applications in organic optoelectronics. However, compared with nonpolar organic semiconductors, electronic polarization for dipolar systems has been rarely studied. Here, taking 1,2,3,4-tetrafluoro-6,7-dimethylnaphthalene as representative, we have calculated the electronic polarization energies of dipolar organic molecular crystals by means of a polarizable force-field method. Surprisingly, our results point to that the polarization energies for this dipolar system are similar to those of nonpolar systems. In addition, the π-π stack contributes only about 30%∼40% to the total polarization energy, thus the polarization effects along the three dimensions should be treated equally even for the one-dimensional stacking crystals.