We studied the optical properties of fac tris(2-phenylpyridine) iridium (Ir(ppy)(3)) emitting layer in single-layer organic light emitting diode (OLED) device and in thin film grown on quartz plate using a phase modulated spectroscopic ellipsometry (PMSE). Accurate spectra of refractive index n and extinction coefficient k of Ir(ppy)(3) were obtained in the wavelength range of 330-830 nm in the device and film. Difference was observed in the n and k spectra between the single layer thin film evaporated on quartz plate and OLED. Additionally difference was found between the layer thickness estimated by quartz oscillator and thickness estimated from the PMSE measurement. (c) 2005 Elsevier B.V. All rights reserved.