Determination of optical constants of pentacene thin film by spectroscopic ellipsometry

We present optical constants [N˜(E)=n(E)+ik(E)] of pentacene in wide spectral range using spectroscopic ellipsometry, emphasizing on the modeling procedure aided by morphological and structural characterizations. For suitable model dielectric function, Classical-Oscillator, Forouhi–Bloomer, and Tauc–Lorentz models were employed considering Kramers–Kronig consistency and density of states in the model. Comparatively, Tauc–Lorentz model with a bilayer stack model was found to be suitable for extraction of meaningful optical parameters. The optical constants, core dielectric constant and the band gap of pentacene are presented along with parameters from six optical transitions.