Optical dielectric function of Si(2,6-bis(benzimidazol-2’-yl)pyridine) 2 determined by spectroscopic ellipsometry

Si(bzimpy)$_2$2, a fluorescent organic complex, has been demonstrated as a potential electron transport and electroluminescent layer for organic electronic devices. Despite the successful synthesis and encouraging electroluminescence at 560 nm, the complex dielectric function of the water-stable complex has not been reported yet. In this letter, we report on the first spectroscopic ellipsometry data obtained from a Si(bzimpy)$_2$2 thin film in the spectral range from 300 nm to 1900 nm (0.65 eV to 4.1 eV). A parameterized model dielectric function composed of a Tauc-Lorentz and Gaussian oscillators is employed to analyze the experimental ellipsometry data. We find a good agreement between the absorption energies observed experimentally here and density functional theory calculations reported earlier.