In-line spectroscopic ellipsometry for the monitoring of the optical properties and quality of roll-to-roll printed nanolayers for organic photovoltaics - Logothetidis, Stergios; Georgiou, Despoina; Laskarakis, Argiris; Koidis, Christos; Kalfagiannis, Nikolaos (Solar Energy Materials & Solar Cells, 2013)