Modeling the optical constants of organic thin films: application to 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA)

We model the optical constants of 3,4,9,10-perylenetetracarboxylic dianhydr ide (PTCDA) using a modified Lorentz oscillator model and compare our resul ts to the conventional Lorentz oscillator model. It is found that an adjust able broadening function incorporated in the modified Lorentz oscillator mo del should be used instead of a Lorentzian broadening function in the conve ntional oscillator model for modeling successfully the optical constants of organic materials. We attribute this to the assumption that each absorptio n peak is composed of a large number of individual transitions closely spac ed in energy. (C) 2000 Published by Elsevier Science B.V.