Exciton energy disorder in polar amorphous organic thin films: Monte Carlo calculations

Publication Type:

Journal Article

Source:

Phys. Rev. B Condens. Matter, American Physical Society, Volume 75, Issue 8, p.081403 (2007)

ISBN:

0163-1829

Keywords:

2007, 2013 and earlier

Abstract:

We report on Monte Carlo calculations of the exciton energy level disorder in polar amorphous organic solids arising from electrostatic interactions
between polarizable molecular charge distributions. In contrast to
previous reports in which the discrete molecular polarizabilities are
modeled as a dielectric continuum having dielectric constant $ϵ$, our
calculations take account of the molecular-scale polarization
inhomogeneity. We demonstrate that exciton energy level disorder is only
weakly dependent on $ϵ$. For a range of $ϵ$ typical of organic solids, we
report an empirical expression for the energy level disorder, and show
that conventional dielectric continuum models are not consistent with the
observed results. Results of our calculations are shown to be consistent
with experimental measurements of exciton energy disorder in aluminum
tris-(8-hydroxyquinoline).