The article deals with determination of complex refractive indexes of organic thin films; the assessment was implemented by spectroscopic ellipsometry. Thin films of Tr-conjugated MDMO-PPV, PCDTBT, and PCBTDPP polymers blended with PC60BM and PC70BM fullerenes were subjected to investigation. Recently, these materials have intensively been studied for their potential application in photovoltaics. This article summarizes research findings on refractive indexes and extinction coefficients of the above studied pure materials and their mixtures. The obtained ellipsometric data were evaluated according to the Tauc-Lorentz model. (C) 2015 Elsevier B.V. All rights reserved.